LNG TANK AND SYSTEM FOR CONNECTING AT LEAST ONE PIPE BETWEEN AN LNG TANK AND A TANK CONNECTION SPACE THEREOF

Abstract

An LNG tank is a single-shell LNG tank having one shell and at least one pipe extending from the LNG tank to a tank connection space of the LNG tank. The shell of the LNG tank is substantially surrounded by insulation. The LNG tank has at least one bellow connection surrounding at least part of the length of the at least one pipe for connecting the at least one pipe extending from the LNG tank to the tank connection space. A system for connecting at least one pipe between an LNG tank and a tank connection space thereof is also provided. At least one pipe extends from the LNG tank to the tank connection space and which LNG tank is a single-shell tank having one shell. The at least one pipe is connected between the LNG tank and the tank connection space by at least one bellow connection.

Claims

1-17. (canceled)

18. A LNG tank, which LNG tank is a single-shell LNG tank having one shell and which LNG tank comprises at least one pipe extending from the LNG tank to a tank connection space of the LNG tank, which shell of the LNG tank is surrounded by insulation and which LNG tank comprises at least one bellow connection surrounding at least part of the length of the at least one pipe for connecting the at least one pipe extending from the LNG tank to the tank connection space, wherein the bellow connection comprises insulation arranged outside the bellows connection and that the insulation arranged outside the bellows connection extends along at least part of the distance between the LNG tank and the tank connection space.

19. The LNG tank according to claim 18, wherein a tank connection space is arranged adjacent to the LNG tank and that the at least one pipe extends from the LNG tank to the tank connection space.

20. The LNG tank according to claim 19, wherein the bellow connection connecting the LNG tank and the tank connection space forms a structure surrounding the at least one pipe, which structure is flexible for compensating changes in distance between a wall of the LNG tank and adjacent wall of the tank connection space caused by temperature differences.

21. The LNG tank according to claim 18, wherein the bellow connection comprises insulation surrounding the at least one pipe.

22. The LNG tank according to claim 18, wherein the bellow connection comprises insulation arranged inside the bellows connection.

23. The LNG tank according to claim 18, wherein the LNG tank comprises at least one pipe extending from above the LNG level (L) of the LNG tank and an upper bellow connection for connecting the at least one pipe and at least one other pipe extending from below the LNG level (L) of the LNG tank and another lower bellow connection for connecting the at least one other pipe.

24. The LNG tank according to claim 19, wherein the bellow connection extends along at least part of the distance between the LNG tank and the tank connection space.

25. The LNG tank according to claim 19, wherein the bellow connection extends into the tank connection space.

26. The LNG tank according to claim 22, wherein the insulation of the bellow connection extends into the tank connection space, which insulation is arranged inside the bellows connection.

27. The LNG tank according to claim 18, wherein the insulation of the LNG tank is polyurethane or vacuum insulated panels.

28. The LNG tank according to claim 21, wherein the insulation of the bellow connection is mineral wool, polyurethane or vacuum insulated panels.

29. The LNG tank according to claim 22, wherein the insulation of the bellow connection is mineral wool, polyurethane or vacuum insulated panels.

30. A ship comprising a tank according to claim 18.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In the following the invention is described in more detail by reference to the accompanying drawing in which

[0045] FIG. 1 shows schematically a prior art LNG fuel distribution architecture,

[0046] FIG. 2 shows schematically an advantageous example of the invention,

[0047] FIG. 3 shows schematically another advantageous example of the invention and

[0048] FIG. 4 shows schematically yet another advantageous example of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] FIG. 1 illustrates schematically the architecture of a known system onboard an LNG-fueled ship. An LNG bunkering station 101 is located on the deck and used to fill up the system with LNG. The LNG fuel storage system comprises one or more thermally insulated gas tanks 102 for storing the LNG in liquid form, and the so-called tank connection space 103 where the LNG is controllably evaporated and its distribution to the engine(s) is arranged. Evaporation means a phase change from liquid to gaseous phase, for which reason all subsequent stages should leave the L for liquefied out of the acronym and use only NG (Natural Gas) instead.

[0050] The engine 104 or engines of the ship are located in an engine room 105. Each engine has its respective engine-specific fuel input subsystem 106, which in the case of gaseous fuel is in some sources referred to as the GVU (Gas Valve Unit). The tank connection space 103 of FIG. 1 comprises two evaporators, of which the first evaporator 107 is the so-called PBU (Pressure Build-Up) evaporator used to maintain a sufficient pressure inside the gas tank 102. Hydrostatic pressure at the inlet of a main supply line 108 inside the gas tank 102 is the driving force that makes the LNG flow into the second evaporator 109, which is the MGE or Main Gas Evaporator from which the fuel is distributed in gaseous form towards the engines. In order to ensure that evaporated gas flows to the GVU(s) and further to the engine(s) at sufficiently high pressure, the PBU system maintains the internal pressure of the gas tank 102 at or close to a predetermined value, which is typically between 5 and 10 bars.

[0051] The engine 104 comprises one or more cooling circuits. Schematically shown in FIG. 1 is an external loop 110 of the so-called low temperature (LT) cooling circuit, which may be used for example to cool lubricating oil. The so-called LT water that circulates in the external loop 110 may have a temperature around 50 degrees centigrade when it goes through a heat exchanger 111, in which it donates heat to a mixture of glycol and water that in turn transfers heat to the evaporators 107 and 109. The glycol/water mixture circuit comprises a circulation pump 112 and an expansion tank 113. Glycol is needed in the mixture to prevent it from freezing when it comes into contact with the extremely cold LNG inlet parts of the evaporators 107 and 109.

[0052] During the course of the following description of FIGS. 2-4 corresponding reference numbers and signs will be used to identify like elements, parts and part components unless otherwise mentioned. In the figures some reference signs have not been repeated for clarity reasons. In the following the examples are described mainly by reference to an LNG tank of a ship or a corresponding ship in view of simplifying the disclosure but it should be noted that instead of this example any type of a tank for LNG can have similar features and properties in accordance with the invention.

[0053] In the examples of FIGS. 2-4 a schematic vertical cross-section of a part of an LNG tank 10 and a tank connection space 20 associated therewith are shown. The LNG tank 10 is a single-shell LNG tank and comprises a shell 14 defining the tank space for the LNG. In the figure the level of the LNG is denoted by reference sign L. The shell 14 is surrounded by insulation 13, which is advantageously VIP (vacuum insulated panels) or PUR (polyurethane).The tank connection space 20 containing the equipment (not shown) for converting the liquid into a gas for safe delivery to the engines, is associated with the LNG tank 10, the equipment being in fluid connection with the LNG tank 10 via pipes 16 and LNG pipes 17, which pipes 16, 17 have one end in the LNG tank 10 and the other end in the tank connection space 20. The pipes 16 are located above the LNG level L of the LNG tank and are for example pipes for safety release valve, level measurement, top spray, sprays denoted by reference sing 24 and try cocks. Try cock is used as an overfill protection. If the LNG level during bunkering reaches the try cock the pipe will be filled with cold LNG and this will trigger an alarm and the bunkering procedure will shut down. The LNG pipes 17 located below the LNG level L are double walled and thus each LNG pipe 17 has an outer pipe 18. These pipes 17 comprise f. ex. bunkering line, fuel line to the engine, level or pressure measurement line, PBE inlet line. The LNG tank 10 and the tank connection space 20 have advantageously wooden legs 21, 22 that support the LNG tank 10 and the tank connection space on the deck 25 or corresponding support structure of the ship. The legs 21 of the LNG tank 10 have a support structure 23 in the tank insulation 13 area.

[0054] In the schematic FIGS. 2-4 are also shown bellow connections 11, 12 for the pipes 16 and LNG pipes 17. The bellow connections 11, 12 are formed as pipe-constructions surrounding the pipes 16, 17, correspondingly, and the pipe construction comprising bellow-structure for compensating the changes of the lengths due to the temperature differences. This enables the LNG tank 10 and the tank connection space 20 to be located adjacent each other, the LNG tank 10 being connected to the tank connection space 20 by the bellow connections 11, 12, which forms a structure surrounding the pipes 16,17 that is flexible for compensating changes in length caused by temperature differences. The bellow connections are made of cold resistant materials, preferably of stainless steel. The bellow connection 11, 12 acts as a secondary barrier in case of leakage of the LNG. The pipes 16, 17 are surrounded by insulation 15 located also around the bellow connection 11, 12, which insulation 15 is for example mineral wool, VIP (vacuum insulated panels) or PUR (polyurethane). The pipes 16, 17 may have further structures inside the tank connection space 20 for compensating changes in their length due to temperature differences.

[0055] In the schematic example of FIG. 2 the upper pipes 16 i.e. the pipes 16 extending into the LNG tank 10 above the LNG level L are surrounded by the upper bellow connection 11 formed of a pipe-construction having bellow-structure as part of the wall of the pipe construction. Also the lower LNG pipes 17 formed to double-walled pipes by the outer pipe 18 and extending to the LNG tank 10 below the LNG level L are surrounded by the lower bellow connection 12 formed of a pipe-construction having bellow-structure as part of the wall of the pipe construction. The bellow connections 11, 12 extend from the wall 14 of the LNG tank 10 into wall of the tank connection space 20. In the area of the tank insulation 13 the insulation 15 for the bellow connections 11, 12 is located inside the pipe-construction of the bellow connection 11, 12 and in the area between outer side of the tank insulation 13 and into the tank connection the insulation is located inside and also around the outside of the bellow construction 11, 12. The bellow structure of the bellow connections 11, 12 extend at least part of the distance between the LNG tank 10 and the tank connection space 20.

[0056] The schematic example of FIG. 3 corresponds substantially to the example of FIG. 2, the differences being that the lower bellow connection 12 has bellow-structure surrounding the pipes inside the tank connection space 20. From the other end the bellows structure 12 is connected to the tank connection space wall, and from the other end it is connected to a flange which the pipes 17 penetrate. The lower bellow 12 can be made this way since the pipes 17 are double walled and thereby have a secondary barrier for leakage of the LNG already. The bellow the connection between the pipes and the tank connection space wall compensates possible movement of the pipes, due to the pipes being attached to the LNG tank wall, and changes of length of the pipes 17, due to temperature differences. This embodiment cannot be made if the pipes 17 are not double walled.

[0057] The schematic example of FIG. 4 corresponds substantially to the example of FIG. 3, the differences being that that the lower bellow connection 12 has only bellow-structure surrounding the pipes just outside the tank connection space 20. The bellow in this example is extending outwards from the tank connection space wall.

[0058] Above only some advantageous examples of the invention have been described to which the invention is not to be narrowly limited. It is clear to one skilled in the art that many modifications and variations are possible within the invention as defined in the following claims.

REFERENCE SIGNS USED IN FIGS. 2-4

[0059] 10 LNG tank

[0060] 11 bellow connection

[0061] 12 bellow connection

[0062] 13 insulation

[0063] 14 shell

[0064] 15 insulation of bellows connection

[0065] 16 pipes from above the LNG level

[0066] 17 LNG pipes

[0067] 18 outer pipe for LNG pipes

[0068] 19 valve

[0069] 20 tank connection space

[0070] 21 foot of LNG tank

[0071] 22 foot of tank connection space

[0072] 23 foot attachment

[0073] 24 spay

[0074] 25 deck

[0075] L level of LNG

[0076] LNG liquefied natural gas

REFERENCE SIGNS USED IN FIG. 1

[0077] 101 LNG bunkering station

[0078] 102 tank

[0079] 103 tank connection space

[0080] 104 engine

[0081] 105 engine room

[0082] 106 fuel input subsystem

[0083] 107 first evaporator

[0084] 108 main supply line

[0085] 109 second evaporator

[0086] 110 external loop of the so-called low temperature (LT) cooling circuit

[0087] 111 heat exchanger

[0088] 112 circulation pump

[0089] 113 expansion tank