METHOD FOR ASSEMBLING A TRANSPORT TANK IN A VESSEL AND A CORRESPONDING VESSEL

Abstract

A method for assembling a transport tank includes the steps of providing a hull with two decks extending substantially in a horizontal direction and being arranged at a distance from each other; arranging a transport tank in the hull with one end wall being arranged near one of the two decks, with another end wall being arranged near the other one of the two decks, and with a tank circumferential wall extending in between the two end walls; forming one or more chambers between the end walls and the corresponding deck; and applying or getting applied an underpressure to the one or more chambers for exerting a pulling force on the external side of the corresponding tank end wall for at least partly withstanding a pulling force on the internal side of the corresponding tank end wall in case of an underpressure in the transport tank.

Claims

1. A method for assembling a transport tank in a vessel, comprising the following steps: providing a hull defining a storage space delimited by two decks extending substantially in a horizontal direction and being arranged at a distance from each other in a vertical direction; arranging a transport tank in the storage space of the hull with one tank end wall being arranged near one of the two decks to extend substantially parallel to said one of the two decks, with another tank end wall being arranged near the other one of the two decks to extend substantially parallel to said other one of the two decks, and with a tank circumferential wall extending in between the two tank end walls, each tank end wall having an internal and an external side; forming one or more chambers between at least one of the tank end walls and the corresponding deck; and applying or getting applied an underpressure in the one or more chambers for exerting a pulling force on the external side of the corresponding tank end wall for at least partly withstanding a pulling force on the internal side of the corresponding tank end wall in case of an underpressure in the transport tank.

2. The method according to claim 1, wherein the underpressure in the one or more chambers is at least 20 mbar, in particular at least 35 mbar, more in particular at least 75 mbar, even more in particular at least 100 mbar, and most particular at least 200 mbar.

3. The method according to claim 1, wherein the one or more chambers are configured such that the underpressure in the one or more chambers at least prevents the corresponding tank end wall from plastically deforming inwards into the transport tank up to an underpressure or a load corresponding to an underpressure of at least 20 mbar in the transport tank.

4. The method according to one claim 1, wherein the underpressure is at least partly applied in the one or more chambers by a vacuum pump connected to the one or more chambers.

5. The method according to claim 4, wherein the underpressure in the one or more chambers is maintained by continuously driving the vacuum pump.

6. The method according to claim 4, wherein the underpressure in the one or more chambers is maintained by closing off the one or more chambers upon reaching the underpressure with the vacuum pump.

7. The method according to one claim 1, wherein the one or more chambers are closed, and wherein the underpressure in the one or more chambers at least partly gets applied by elastic deformation of the corresponding tank end wall inwards into the transport tank causing the volume of the one or more chambers to increase.

8. The method according to claim 1, wherein the one or more chambers are closed and at least partially filled with a gas, and wherein at least 98% of the gas inside the one or more chambers is inert, preferably nitrogen.

9. The method according to claim 1, wherein the one or more chambers are provided with support elements between the tank end wall and the corresponding deck to support the tank end wall.

10. The method according to claim 1, wherein the one or more chambers are at least partially filled with insulation material.

11. The method according to claim 10, wherein at least part of the insulation material forms at least a part of the support elements.

12. A vessel comprising: a hull defining a storage space delimited by two decks extending substantially in a horizontal direction and being arranged at a distance from each other in a vertical direction; a transport tank in the storage space of the hull, the transport tank comprising: a tank end wall being arranged near one of the two decks to extend substantially parallel to said one of the two decks; another tank end wall being arranged near the other one of the two decks to extend substantially parallel to said other one of the two decks, each tank end wall having an internal and an external side, a tank circumferential wall extending in between the two tank end walls; and one or more chambers between at least one of the tank end walls and the corresponding deck, wherein the one or more chambers are provided with an underpressure for exerting a pulling force on the external side of the corresponding tank end wall for at least partly withstanding a pulling force on the internal side of the corresponding tank end wall in case of an underpressure in the transport tank, and/or wherein the one or more chambers are closed, wherein the corresponding tank end wall is elastically deformable for getting an underpressure at least partly applied in the one or more chambers by elastic deformation of the tank end wall inwards into the transport tank causing the volume of the one or more chambers to increase.

13. The vessel according to claim 12, wherein the one or more chambers are configured so as to prevent the corresponding tank end wall from plastically deforming inwards into the transport tank up to an underpressure or a load corresponding to an underpressure of at least 20 mbar in the transport tank.

14. The vessel according to claim 12, wherein the external side of the corresponding tank end wall at least partly faces the inside of the one or more chambers, and wherein in particular at least 20% of the corresponding tank end wall is facing the inside of the one or more chambers, and wherein more in particular at least 50% of the corresponding tank end wall is facing the inside of the one or more chambers, and wherein even more in particular at least 80% of the corresponding tank end wall is facing the inside of the one or more chambers.

15. The vessel according to claim 12, wherein a vacuum pump is provided that is connected to the one or more chambers for at least partly applying the underpressure in the one or more chambers.

16. The vessel according to claim 12, wherein the one or more chambers are closed and at least partially filled with a gas, and wherein at least 98% of the gas inside the one or more chambers is inert, preferably nitrogen.

17. The vessel according to claim 12, wherein the one or more chambers are provided with support elements between the tank end wall and the corresponding deck to support the tank end wall.

18. The vessel according to claim 12, wherein the one or more chambers are at least partially filled with insulation material.

19. The vessel according to claim 18, wherein at least part of the insulation material forms at least a part of the support elements.

20. The vessel according to claim 12, wherein the one or more chambers are provided at least at a circumferential part of the corresponding tank end wall.

21. The vessel according to claim 12, wherein the one or more chambers are provided at substantially the entire corresponding tank end wall.

22. The vessel according to claim 12, wherein a sealing skirt is arranged between the transport tank and the corresponding deck, in particular wherein the sealing skirt comprises an elastically deformable part and/or telescoping parts.

23. The vessel according to claim 12, wherein the corresponding tank end wall has a thickness of less than 10 mm, and/or wherein the corresponding tank end wall forms a flexible membrane.

24. The vessel according to claim 12, further comprising deformation absorbers in the tank circumferential wall or between the transport tank and the hull to absorb deformations of the hull in at least the vertical direction.

25. The vessel according to claim 24, wherein the deformation absorbers are provided between the tank circumferential wall and the two decks of the hull, respectively, to form a seal between the transport tank and the two decks of the hull, respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The invention will now be described in a non-limiting way by reference to the accompanying drawings in which like parts are indicated by like reference symbols, and in which:

[0073] FIG. 1A depicts a cross section of a vessel according to an embodiment of the invention;

[0074] FIG. 1B depicts a detail of the cross section of FIG. 1A;

[0075] FIG. 2A-2J depict various embodiments of the bottom tank end wall and the one or more chambers in between the bottom tank end wall and the lower deck;

[0076] FIG. 3A shows a schematic view of a lower part of the tank of FIG. 1 with atmospheric pressure both inside the chamber as well as inside the tank, causing the bottom tank end wall to remain undeformed;

[0077] FIG. 3B shows the view of FIG. 3A with an underpressure that has started to occur inside the tank, that has caused the bottom tank end wall to get elastically deformed upwards until a substantially equal underpressure has started to occur inside the chamber;

[0078] FIG. 4A shows the view of FIG. 3A with atmospheric pressure inside the tank and with an initial underpressure inside the chamber, causing the bottom tank end wall to be drawn against an insulation layer;

[0079] FIG. 4B shows the view of FIG. 4A with an underpressure that has started to occur inside the tank, that has not caused the bottom tank end wall to get elastically deformed upwards because of the underpressure inside the chamber still being larger than the underpressure inside the tank;

[0080] FIG. 4C shows the view of FIG. 4B with the underpressure inside the tank having become larger than the initial underpressure inside the chamber, which has caused the bottom tank end wall to get elastically deformed upwards until a substantially equally larger underpressure has started to occur inside the chamber;

[0081] FIG. 5A shows a schematic view of an upper part of the tank of FIG. 1 in which a safety delimiter is provided in the chamber;

[0082] FIG. 5B shows the view of FIG. 5A when an initial underpressure in the chamber has fallen away;

[0083] FIG. 6 shows a schematic view of a lower part of the tank of FIG. 1 with a sealing skirt arranged between the circumferential tank wall and the lower deck;

[0084] FIG. 7 shows the view of FIG. 6 with the sealing skirt arranged between the bottom tank end wall and the lower deck; and

[0085] FIG. 8 shows the view of FIG. 6 with the sealing skirt forming a telescopic part with the circumferential tank wall.

DETAILED DESCRIPTION OF THE INVENTION

[0086] The vessel 1 comprises a hull 3 in this embodiment with a lower deck 4, an upper deck 5 and side walls 6, 7 delimiting a storage space 8.

[0087] In the storage space 8, a transport tank 10 is arranged having a bottom tank end wall 11 arranged near the lower deck 4 and extending substantially parallel to the lower deck 4, a top tank end wall 12 arranged near the upper deck 5 and extending substantially parallel to the upper deck 5, and a tank circumferential wall 13 extending in between the bottom tank end wall 11 and top tank end wall 12 substantially perpendicular to both tank end walls 11, 12.

[0088] The tank circumferential wall 13 may be cylindrical or may have a substantially polygonal shape in plan view, wherein preferably the corners of the polygonal shape are rounded.

[0089] Although in FIG. 1A only one transport tank 10 is shown, it will be apparent that the vessel 1 may comprise a plurality of similar transport tanks 10.

[0090] To fill the transport tank 10, a fill port 14 may be provided in the top tank end wall 12, which fill port 14 preferably extends through the upper deck 5 allowing to fill the transport tank 10 from above the upper deck 5.

[0091] To empty the transport tank 10, a pump well 15 may be provided in the bottom tank end wall 11, wherein the pump well 15 preferably forms the lowest point of the bottom tank end wall so that all medium in the transport tank will flow towards the pump well 15 for an efficient emptying of the transport tank 10.

[0092] Between the bottom tank end wall 11 and the lower deck 4, a chamber 20 is provided, and between the top tank end wall 12 and the upper deck 5, a chamber 30 is provided. The circumferential wall 13 is free from the sidewalls 6 and 7, so that the transport tank is accessible using the space in between the sidewalls 6, 7 and the circumferential wall 13 and so that the sidewalls 6, 7 may deform without affecting the transport tank.

[0093] When emptying the transport tank, an underpressure may be applied to the interior of the transport tank 10. This underpressure can apply relatively large forces to the bottom tank end wall 11 and the top tank end wall 12 with plastic deformation as a result, which is undesirable.

[0094] Hence, according to the invention an underpressure is applied to the chambers 20 and 30, such that plastic deformation of the respective bottom tank end wall 11 and top tank end wall 12 can be prevented up to an underpressure of at least 20 mbar in the transport tank, preferably up to an underpressure of at least 35 mbar, more preferably up to an underpressure of at least 75 mbar, even more preferably up to an underpressure of at least 100 mbar, and most preferably up to an underpressure of at least 200 mbar.

[0095] Preventing plastic deformation using underpressure on the respective bottom tank end wall and top tank end wall can be achieved in various ways including but not limited to: [0096] 1) applying a permanent underpressure of at least 20 mbar, preferably of at least 35 mbar, more preferably of at least 75 mbar, even more preferably of at least 100 mbar, and most preferably of at least 200 mbar to the chambers 20 and 30; [0097] 2) temporarily applying an underpressure of at least 20 mbar, preferably of at least 35 mbar, more preferably of at least 75 mbar, even more preferably of at least 100 mbar, and most preferably of at least 200 mbar to the chambers 20 and 30, e.g. only in cases when an underpressure in the transport tank is expected; [0098] 3) applying an initial pressure to the chambers 20 and 30, and subsequently closing off the chambers, wherein the chambers 20 and 30 are dimensioned such that elastic deformation of the respective tank end walls 11, 12 inwards into the tank 10 causes a volume increase of the chambers 20, 30 leading to an underpressure in the chambers 20 and 30 of at least 20 mbar, preferably of at least 35 mbar, more preferably of at least 75 mbar, even more preferably of at least 100 mbar, and most preferably of at least 200 mbar.

[0099] In the embodiment of FIGS. 1A and 1B the chambers are filled with insulation material 40 providing thermal insulation, which is especially advantageous when the medium in the transport tank is held at a temperature different from the environment. The insulation material 40 is in this case also embodied to function as support element to support the bottom tank end wall 11 and top tank end wall 12 in case of an overpressure in the transport tank 10 urging the tank end walls 11, 12 outwardly. The tank end walls will then engage with the insulation material and prevent any further deformation.

[0100] FIG. 1A further discloses a vacuum pump 50 connected to the chamber 20 via tubing 51. The vacuum pump is able to apply an underpressure to chamber 20. The vacuum pump is depicted using dashed lines as in an embodiment, the vacuum pump is only temporarily present, namely once to apply the desired underpressure after which the chamber 20 is closed off to maintain this underpressure. The same vacuum pump 50, or another vacuum pump may also be connected to chamber 30.

[0101] However, the vacuum pump may also be provided more permanently, e.g. when maintaining the underpressure can only be achieved by continuously driving the vacuum pump. This may also apply to the situation that the underpressure is only applied temporarily, e.g. only in case an underpressure can occur in the transport tank, in particular during emptying and/or cleaning.

[0102] Especially when the chambers 20 and 30 are closed off, a vacuum detection system 60 may be provided allowing to monitor the pressure inside the chamber 20, and possibly also inside chamber 30, thereby allowing to monitor the risk of plastic deformation of the tank end wall and e.g. to indicate whether pressure is lost, for instance due to a leak.

[0103] The circumferential wall 13 comprises deformation absorbers 70 to absorb deformations of the hull 3 in at least the vertical direction.

[0104] FIGS. 2A-2J depict various embodiments of the bottom tank end wall 11 and the one or more chambers 20 in between the bottom tank end wall 11 and the lower deck 4. The FIGS. 2A-2J only depict half of the cross section as the other half is symmetrical about a centre C or can easily be derived from the shown half.

[0105] Although FIGS. 2A-2J depict various embodiments in relation to the bottom tank end wall 11, the embodiments can also or alternatively be applied to the top tank end wall 12.

[0106] FIG. 2A depicts a variant in which there is a single chamber 20 between the bottom tank end wall 11 and the lower deck 4, which chamber is closed off as indicated in the detailed drawing on the right of FIG. 2A and has a relatively small volume. The small volume allows prevention of plastic deformation by creating sufficient underpressure due to elastic deformation of the bottom tank end wall caused by underpressure in the transport tank. The initial pressure in the chamber 20, i.e. the pressure in the chamber 20 in an undeformed state of the bottom tank end wall may then even be an overpressure or atmospheric pressure.

[0107] FIG. 2B depicts a variant in which there is a single chamber 20, which is partially filled with insulation material 40, which also acts as support element. The bottom tank end wall 11 is sloped towards the centre C of the bottom tank end wall 11 to end in a pump well 15.

[0108] FIG. 2C depicts a variant similar to the variant of FIG. 2B, but with the difference that the pump well 15 is now located near the circumferential wall 13 and the bottom tank end wall is sloped towards the pump well 15 which slope extends beyond the centre C of the transport tank.

[0109] FIG. 2D depicts a variant in which the bottom tank end wall 14 is curved with the closest distance to the lower deck 4 at the centre C of the bottom tank end wall 11. This variant may be assembled by providing the insulation material 40 in the desired shape, providing a flat bottom tank end wall 11 and apply an underpressure to the chamber 20 thereby pulling the bottom tank end wall 11 towards or even against the insulation material 40. Advantage of this assembly feature is that the bottom tank end wall is less susceptible for folding due to e.g. thermal compression stresses in the bottom tank end wall 11.

[0110] FIG. 2E depicts a variant in which there is a single chamber 20 which lower half is filled with insulation material 40 and which upper half comprises conduits 80 allowing to transport cooling or heating medium. The conduits 80 may also be integrally formed with the bottom tank end wall 11 thereby forming a channel plate.

[0111] FIG. 2F depicts a variant similar to the variant of FIG. 2E, but in which the bottom tank end wall is formed as a pillow plate forming channels 90 to transport cooling or heating medium.

[0112] FIG. 2G depicts a variant in which support elements 100 are provided to support the bottom tank end wall, especially in case of overpressure in the transport tank. In between the support elements 100, insulation material 40 is provided. The support elements 100 may divide the space below the bottom tank end wall into a plurality of chambers, but the support elements may also be provided in the form of blocks or cylindrical elements.

[0113] FIG. 2H depicts a variant in which insulation material 40 is stacked with tubing 110, preferably spirally shaped tubing 110. The tubing may be used for transporting heating or cooling medium, in which case the tubing may be rigid, but may alternatively be filled with gas to provide an air spring.

[0114] FIG. 2I depicts a variant similar to the variant of FIG. 2H as it includes the tubing 110, but lacks the insulation material 40. Further, the deformation absorbers are here provided in between the circumferential wall 13 and the lower deck 4, but may alternatively be also provided between the bottom tank end wall 11 and lower deck 4.

[0115] FIG. 2J depicts a variant in which a central portion of the bottom tank end wall is supported by insulation material 40 and the tubing 110 is provided at a circumferential portion of the bottom tank end wall 11.

[0116] In FIGS. 3 and 4 some possible situations are shown that may occur with the tank 10 of FIG. 1 in dependency of initial pressures in the chamber 20 and in dependency of pressures that occur inside the tank 10.

[0117] In FIG. 3A a starting situation is shown in which the closed chamber 20 is applied with an initial atmospheric pressure, that is to say no underpressure and no overpressure, here referred to as Pc=Patm. The chamber 20 here has an initial volume Vi. The tank 10 here is empty and inside the tank 10 also an atmospheric pressure occurs, here referred to as Pt=Patm.

[0118] In FIG. 3B it is shown that an underpressure of 50 mbar, here referred to as Pt=Patm50 mbar, has started to occur inside the tank 10. Because of this an upwards directed pulling force gets exerted by this underpressure Pt onto the internal upper side of the bottom tank end wall 11. This upwards directed pulling force onto the internal upper side of the bottom tank end wall 11 causes the bottom tank end wall 11 to elastically deform upwards. This increases the initial volume Vi of the chamber 20 with an extra volume Ve. This volume increase of the closed chamber 20, causes the initial pressure Pc inside the chamber 20 to drop, and stops as soon as a balanced situation is obtained again. In this balanced situation the underpressure Pc inside the chamber 20 has become substantially the same as the underpressure Pt inside the tank 10, that is to say Pc=Pt=Patm50 mbar. With this it is noticed that the bottom tank end wall 11 itself also exerts a force to pull it back towards its undeformed starting position. The underpressure inside the chamber therefore is deemed to be slightly higher than the underpressure inside the tank in this situation.

[0119] In FIG. 4A a starting situation is shown in which the closed chamber 20 is applied with an initial underpressure of 75 mbar, here referred to as Pc=Patm75 mbar. The chamber 20 here has an initial volume Vi. The tank 10 here is empty and inside the tank 10 an atmospheric pressure occurs, here referred to as Pt=Patm. In this situation a downwards directed pulling force gets exerted by the underpressure Pc onto the external lower side of the bottom tank end wall 11. This downwards directed pulling force onto the external lower side of the bottom tank end wall 11 causes the bottom tank end wall 11 to get pulled downwards against the insulation material 40.

[0120] In FIG. 4B it is shown that an underpressure Pt=Patm50 mbar has started to occur inside the tank 10. However, since this underpressure Pt=Patm50 mbar in the tank 10 is still less strong than the underpressure Pc=Patm75 mbar in the chamber 20, the bottom tank end wall 11 shall remain being pulled against the insulation material 40.

[0121] In FIG. 4C it is shown that an underpressure Pt=Patm100 mbar has started to occur inside the tank 10. Since this underpressure Pt=Patm100 mbar in the tank 10 is stronger than the initial underpressure Pc=Patm75 mbar in the chamber 20, the bottom tank end wall 11 shall no longer remain being pulled against the insulation material 40. Instead the upwards directed pulling force that gets exerted by the increased underpressure Pt onto the internal upper side of the bottom tank end wall 11, shall cause the bottom tank end wall 11 to elastically deform upwards. The corresponding volume increase of the closed chamber 20, then causes the initial pressure Pc inside the chamber 20 to drop, and become substantially the same as the underpressure Pt inside the tank 10, that is to say Pc=Pt=Patm100 mbar. Here also it is noticed that the bottom tank end wall 11 itself also exerts a force to pull it back towards its undeformed starting position. The underpressure inside the chamber therefore is deemed to be slightly higher than the underpressure inside the tank in this situation.

[0122] In FIG. 5A the chamber 30 of FIG. 1 that is present between the upper deck 5 and the top tank end wall 12 is shown with the insulation material 40 being provided therein. It can be seen here that hook-shaped safety delimiters 120, 121 are connected to the top tank end wall 12 and upper deck 5 respectively. Those delimiters 120, 121 are slidable relative to each other in the vertical axial direction over a maximum distance yl. In FIG. 5A a situation is shown in which an underpressure Pc has been applied in the chamber 30 that causes the top tank end wall 12 to be pulled against the insulation material 40 as long as this underpressure Pc leads to larger upwards pulling forces getting exerted onto the top tank end wall 12 than downwards directed pulling forces acting thereupon. Those downwards directed pulling forces then comprise the downwards directed weight load of the top tank end wall 12 if applicable added with downwards directed pulling forces caused by an underpressure Pt that may start to occur inside the tank 10.

[0123] In FIG. 5B the situation is shown in which the underpressure Pc in the chamber 30 has fallen away, for example because of the chamber 30 no longer being sealed properly or because of the vacuum pump 50 no longer functioning properly. In that situation the top tank end wall 12 no longer shall be pulled upwards against the insulation material 40 but shall elastically deform downwards at least under its own weight and possibly also because of an underpressure Pt occurring inside the tank 10. As a redundant safety measure the top tank end wall 12 then can be prevented from starting to plastically deform owing to the delimiters 120, 120 reaching their end positions in which they hook against each other.

[0124] In FIG. 6 a variant is shown in which a sealing skirt 130 is fixedly arranged between the lower deck 4 and a connecting ring 131 that is welded to the circumferential tank wall 13. The sealing skirt 130 closes of the chamber 20 around its entire circumference. In the alternative the sealing skirt 130 may also be arranged between the bottom tank end wall 11 and the lower deck 4. This is shown in FIG. 7.

[0125] In FIG. 8 a variant is shown in which the sealing skirt 130 comprises two telescoping parts 132, 133 of which one is connected to the circumferential tank wall 13, whereas the other one is connected to the lower deck 4. The telescoping parts 132, 133 are telescopingly slideable relative to each other in the vertical direction while substantially maintaining a gastight seal between them. For this a sealing organ 134 is provided in between the two telescoping parts 132, 133.

[0126] Besides the embodiments shown numerous variants are possible. For example the shapes and dimensions of the various parts may differ. Also the initial pressures and/or underpressures applied to the chambers may differ.

[0127] Thus an environmental friendly vessel with transport tank is provided of which the transport tank can be easily and quickly assembled into the vessel in an economic manner and which transport tank then is optimally protected against situations in which an underpressure may start to occur inside the transport tank itself, in particular during emptying and/or cleaning.