DE202009011136U1 - Modular tank for liquefied gas transport - Google Patents

Abstract

Cargo tanks (independent tanks) for installation in the holds of ships for liquefied gas transport (LNG or PLNG), characterized in that the independent tanks are generally of parallelepiped shape and bounded by a spatial frame of pipes of suitable cross-section and that in the frame fields a support grid of juxtaposed, lying in the plane of the field and each other is used with the frame gas-tight connected bowls

Description

The gas tankers currently operating as bulk carriers transport natural gas as liquefied natural gas (LNG). Thus, the liquid state of methane (methane as the main component of the natural gas) at a pressure of 1 bar and the temperature of -162 ° C is designated and used for transport. The transported mass of liquid natural gas is relatively high due to the high density of methane in the liquid state (about 0.425 kg / dm ³ ). All conditions of the natural gas at higher temperatures and higher pressures lead to a decrease in the natural gas mass per transport unit due to lower density.

The Gas tankers operate at slightly lower temperatures of -162 ° C to -164 ° C to the while driving reduce exhaust gas entering through rising temperatures. In addition, the higher levels contained in natural gas shift Homologues of hydrocarbons the vapor pressure curve for the mixture to slightly higher temperatures.

Two Forms of transport have become internationally accepted.

The Ball tank system (after Moss-Rosenberg), in which approx Spherical tanks made of stainless steel or aluminum alloy with a diameter of 40 m or more to transport the liquid Gases are used. The spherical tanks are ship-independent Tanks, self-supporting and not part of the hull.

The Membrane systems (from Gaztransport and Technigaz). This is to integrated tanks, which are integrated into the hull and are not self-supporting.

Both Systems use the above-mentioned operating state 1 bar pressure and a temperature of below -162 ° C.

The Transport containers of both systems are insulated to the Liquefied natural gas for a long time without cooling to keep below its boiling point and the cold influence on to prevent the transport system hull. In order to if embrittlement of the hull is avoided which lead to its destruction under load would.

Of the Disadvantage of these transport systems is that the so equipped Ships are very bulky, so long construction times and as a result have high costs. Necessary repairs to the transport system can only run at a very high cost become.

To improve the economic problem, there are a number of technical solutions, which are described in patents and which work partly in the range of higher pressures. However, they could not prevail so far because with the higher pressures along the vapor pressure curve of methane simultaneously reduces the density of the liquid phase and thus the transport mass is reduced at the same transport volume. This includes the utility model DE 29824939 U1 with horizontal tube containers in the ship for LNG transport at higher pressures.

in the U.S. Patent 3,414,155 is an independent tank with tube walls for gas transport at for liquefied gases at room temperature.

A new solution for gas transport in the form of LPG was given in the utility model 20 206 020 562.4. It consists of tubular containers, stored in container skids of ships.

aim The invention is the development of a suitable for ships Transport system for liquefied natural gas, used in the Compared to existing systems to about the same transport masses at the same volume, but in the manufacture of the ship essential Saves costs.

According to the invention proposed for liquefied gas transport Ships as bulk independent LPG tanks in cuboid form, adapted to the cargo hold of the ship, whereby walls, floor and ceiling of the tank in lightweight construction designed as a shell design.

Of the independent tank has a framework of pipes, which span a space as edges and their cross-section to the purpose is adapted and preferably rectangular. In this framework are as closing walls supporting grids made of shells used, with the individual shells so interconnected are that they form a level wall and into the pipe frame can be used and connected. Form these shell gratings so that the walls, the ceiling and the floor of the independent Tanks.

Preferably, the individual shells have a semicircular shape. To form the required double barrier of an independent tank, the individual shell segments of a shell grid are doubled. In this case, two identical shells are arranged at a fixed distance from each other, connected to each other at the edges and thus form a double wall with enclosed space. This double shell segments are joined together to form a wall shell module, the double shell segments at the edges by means of webs rigidly connected to each other who and the webs continue the double wall function. The double shell function has the advantage of ensuring the same strength of the wall in case of leakage of the first barrier. The concave side of the individual shell elements should preferably be arranged to the tank interior in order to prevent or reduce the liquid shock (sloshing) in the tanks due to ship movement, caused by the movement of the ship in the sea state. In the shell double wall, the outer shell may be replaced by a construction of planar components.

The LPG tanks stand on supports of low thermal conductivity, which are fixed in the appropriate grid on the raised floor. At the tank side walls attached supports against Forces from ship movements, especially when the ship is sailing in swell, suitably adjustable anchorages are lower Thermal conductivity at the ship's inner wall and attached to the bulkheads. These inventive Anchors are preferably based on known hydraulic cylinders, a control of the hydraulic piston for two operating conditions own, in which they can be locked. The control can be done manually or automatically. Both operating conditions apply the ride on the sea in sea state. The one operating condition concerns the loaded ship with tanks containing liquefied gas are filled. In this operating condition, the tank has Liquefied gas has a temperature of about -162 ° C and assuming a linear expansion of the tank of about 40 m, the tank shrinks from room temperature by about 90 mm. The other operating state is that of the empty ship with one Tank temperature of maximum room temperature.

The Wall shell modules of floor and ceiling of LPG tanks are preferably in the middle by a collective pipe separated, in which the shell segments of the module are incorporated gas-tight. The wall shell modules of the floor can be under a small Angle from the longitudinal tube to the tank side rise to so the inflow of liquefied gas to the longitudinal tube to facilitate the emptying of the tank and the wall shell modules the ceiling can be at a slight angle from the longitudinal tube fall down to the tank side to the collection of gas in the longitudinal tube to facilitate. In the middle of the tank a vertical pipe is arranged, which is supported on the longitudinal tube of the soil and through the longitudinal tube of the ceiling into a dome for gas collection leads. All pipes are gas-tight and connected have suitable openings at the joints for the passage of liquefied gas.

The Outside of the cuboid liquid gas tank carries an open or closed supporting wall, on which one Cold insulation is attached.

When Material for the components of the tank come several Material types in question, which the conditions of low temperature with sufficient toughness and sufficient Have strength. This can be a high strength alloy steel with a Nickel content to be 9% at low temperature of about -162 ° C has a sufficient fracture toughness or a high strength Aluminum alloy, suitable for low temperatures. A Another possibility is the use of fiber-reinforced Plastics, which also have sufficient strength and fracture toughness for those lower temperatures have and besides have the advantage of low mass. Also a mixed or composite construction the mentioned materials is conceivable.

By the transport form of liquid according to the invention Natural gas in cuboid tanks from wall shell modules can expanded the transport area for liquid natural gas become. This makes it possible with the transport form of natural gas not only in the LNG operating state at a temperature of about -162 ° C and a pressure of 1 bar to transport. The transport area of the operating state of liquid natural gas LNG is through the tank shape according to the invention to a whole Range of operating state of natural gas extended. This area ranges according to the vapor pressure curve for methane at Pressure from 1 to 15 bar and an associated temperature from -162 ° C to -114 ° C.

With the possible extension of the operating state LNG for a whole range of operating conditions by the proposed inventive constructive tank structure is the use of the transport form for the whole o. a. Temperature- and pressure range of the liquid natural gas according to the Vapor pressure curve of methane possible. This will be the LNG transport (LNG = Liquefied Natural Gas) also for PLNG transport (PLNG = Pressurized Liquefied Natural Gas) and the LNG tanker with the inventive Tankform can also be used as a PLNG tanker.

The Density of methane has about 10 bar and -124 ° C by about 12% and at about 15 bar and -115 ° C to about 20% compared to LNG decreased, resulting in a corresponding Reduction of the transport mass by the same size at the same transport volume leads. However, for the same heat flow, the insulation of the cargo space accordingly be reduced. This shows that in the claimed operating condition range Special optimizations of the total costs are possible.

embodiment

The The invention will be closer to exemplary embodiments explained.

1 shows a perspective view of the liquid gas tank ( 1 ), consisting of tank bottom ( 2 ), Tank cover ( 3 ), Tank sidewall ( 4 ) and tank transverse wall ( 9 ), whose fields consist of double shells in the framework ( 5 ) are attached from square tubes. A strength framework ( 6 ) supports the shell rust of the side panels. Floor and ceiling have longitudinal tubes in the middle of the field ( 7 ) and in the center of the tank is a vertical central tube ( 8th ) from the bottom of the tank ( 2 ) through the tank ceiling ( 3 ) to the cathedral ( 8.1 ) leads.

2 shows a section in the transverse direction of a double shell panel with the inner wall 10 and the outer wall 11 and the jetties 12 and 13 ,

3 shows a cross section through a built-in cargo hold of a ship LPG tank with tank bottom ( 2 ) Tank cover ( 3 ), Tank sidewall ( 4 ), Framework ( 5 ), Strengths framework ( 6 ), Longitudinal tube ( 7 ), vertical central tube ( 8th ) and tank dome ( 8.1 ). Furthermore, floor supports ( 24 ), Side supports ( 23 ) and the tank insulation ( 15 ). The hull ( 16 ) is shown by the ship's outer skin ( 17 ), Loading space wall ( 18 ), Raised floor ( 19 ), Ship's main deck ( 21 ), Side supports ( 22 ), and inspection ( 20 ).

4 shows a horizontal section with a view from above through a tank, installed in the hold of a ship, with tank bottom ( 2 ), Tank sidewall ( 4 ), Tank frame ( 5 ), Tank transverse wall ( 9 ) and the two adjacent cargo compartment bulkheads ( 26 ) and ( 27 ).

5 shows an example of the insulation of the tank with the tank inner wall ( 10 ), the tank outer wall ( 11 ), the footbridge ( 13 ). The holder ( 31 ) carries the supporting wall ( 14 ) for the tank insulation ( 15 ) with cladding ( 30 ). In addition to the operation ( 20 ), the ship's inner wall ( 18 ).

6 shows an example of the support of the tank on the raised floor ( 19 ) with tank frame ( 5 ), Bulkhead for tank insulation ( 14 ), Tank insulation ( 15 ), Cladding ( 30 ), Pressure piece ( 28 ), Buffer plate ( 29 ) and ground foundation ( 32 ).

7 shows an example of a side adjustable for the operating state support the tank ( 6 ) by a support system attached to the load compartment wall ( 18 ), with hydraulic cylinder ( 26 ), Hydraulic connection ( 27 ), Pressure piece ( 28 ) and lateral support foundation ( 31 ) on the tank wall ( 6 ) is attached.

1

LPG tank

2

tank bottom

3

tank top

4

Tank sidewall

5

tank frame

6

strength frame

7

longitudinal tube

8th

central tube

8.1

tank dome

9

Tank bulkhead

10

Tank inner wall

11

Tank outer wall

12

web

13

web

14

supporting wall for tank insulation

15

tank insulation

16

hull

17

Ship hull

18

Hold wall

19

Raised floor

20

inspection tour

21

Ship main deck

22

side supports

23

tank support laterally

24

tank support below

25

upper deck

26

bulkhead front

27

bulkhead behind

28

Pressure piece with support laterally

29

buffer plate

30

paneling

31

bracket

32

floor foundation

33

support foundation below

34

hydraulic cylinders

35

hydraulic connection

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 29824939 U1 [0009]
• - US 3414155 [0010]

Claims (11)

Cargo tanks (independent tanks) for installation in the holds of ships for liquefied gas transport (LNG or PLNG), characterized in that the independent tanks are generally of parallelepiped shape and bounded by a spatial frame of pipes of suitable cross-section and that in the frame fields a support grid of juxtaposed, lying in the plane of the field and each other with the frame is connected gas-tight connected shells Cargo containers (independent tanks) according to claim 1, characterized in that the shells a double wall form, with a fixed constant distance of the shells from each other and that the individual shells gas-tight with each other and with the frame are connected and reinforced at the joints by webs are and that the webs at the junction of the shells a double wall form. Cargo containers (independent tanks) according to claim 1 and 2, characterized in that the double wall by a tank inside lying shell support grid and formed on the tank outside by a flat plate becomes. Cargo containers (independent tanks) according to claim 1 and 2, characterized in that the curved Shells of the carrier grate preferably circular Cross-section and have the concave sides of the shells preferably directed to the inside of the tank. Cargo containers (independent tanks) according to claim 1 to 4, characterized in that the space between the double shells of the shell wall with insulating material or a Connecting material is filled Cargo containers (independent tanks) according to claim 1 to 5, characterized in that the tanks high-strength cold-tough steel and / or fiber-reinforced Plastics and / or high-strength cold-resistant aluminum alloy or composite materials. Cargo containers (independent tanks) according to claim 1 to 6, characterized in that on the outside the tanks attached / fixed an adequate cold insulation is. Cargo containers (independent tanks) according to claim 1 to 7, characterized in that preferably the shell support gratings of ceiling and floor preferably are separated halfway and in one at this point lying equal or larger horizontal cross tube open gas-tight integrated. Cargo containers (independent tanks) according to claim 1 to 8, characterized in that preferably compared to the planar arrangement in the reference cuboid the Shell support gratings of the ceiling in a slightly sloping Angle from the cross tube to the end of the tank and the shell support grid of the ground at a slightly rising angle from the crossbar to the End of the tank are arranged. Cargo containers (independent tanks) according to claim 1 to 9, characterized in that preferably in the middle of the tank a vertical pipe is arranged, the supported on the ground and suitable openings has to load and unload and which is stored in the ceiling and has suitable openings for collecting gas in the hold and that opens above the ceiling into a gas collection dome. Cargo containers (independent tanks) according to claim 1 to 10, characterized in that the tanks in suitable to the side walls of the hull are supported and that these supports preferably known hydraulic systems are and these hydraulic systems one Have control to adapt the support to the Temperature expansion of the tanks.