WO2016083438A1

WO2016083438A1 - Tank with sloshing bulkheads

Info

Publication number: WO2016083438A1
Application number: PCT/EP2015/077608
Authority: WO
Inventors: Steinar OPPEDAL; Arne MORTENSEN; Ann Rigmor NERHEIM
Original assignee: Rolls Royce Marine AS
Current assignee: Kongsberg Maritime AS
Priority date: 2014-11-25
Filing date: 2015-11-25
Publication date: 2016-06-02
Anticipated expiration: 2017-05-25
Also published as: NO338150B1; NO20141414A1

Abstract

The present invention relates to a tank, where the tank comprises an elongated and hollow vessel, each end of the vessel being closed by an end cap, where 2N bulkheads with curved surfaces are arranged within the vessel, a bulkhead nearest one end cap of the tank has a concave surface facing said end cap and a subsequent following bulkhead as a convex surface facing said end cap, any further bulkheads being arranged with alternating concave and convex surfaces relative said end cap, N being an integer from 1 to infinite.

Description

TANK WITH SLOSHING BULKHEADS

The present invention relates generally to a fluid containment and delivery tank. More particularly, the present invention relates to a vessel provided to prevent and/or reduce pressure loss due to sloshing phenomena.

Large tanks, typically cylindrical in shape, are used for bulk storage and transportation of a fluid. The term "fluid" as used herein denotes liquid as well as gaseous substances. During transportation of relatively larges volumes of fluid such as by ship, vehicle or rail car, the fluid within the vessel may tend to slosh forward and aft. This sloshing movement can result in instability within the load and may ultimately lead to rollover of the vessel and/or means of transportation, potentially leading to damage to person and property. Further, the continual sloshing movement of the liquid within the vessel can damage the vessel by putting pressure on its welds and joints.

To reduce the destabilization caused by the movement of fluids within the vessel, the vessel may be filled to capacity. This may often not be possible or desirable. For instance, different regulations may limit the filling of the vessel to a filling density of not more than 20% and less than 80% by volume. Such filling restrictions, however, do not apply if the vessel has dividers that apportion the vessel into compartments not exceeding a given capacity.

Dividers, also referred to as baffles, partitions, bulkheads or surge plates, are used to reduce sloshing of the fluid within the vessel and to provide increased stability. Dividers are typically secured at right angles to the anticipated movement of fluids within the tank. Such dividers generally form smaller compartments within the vessel, limiting the distance that the liquid can slosh within the tank. Some examples of vessels that contain these types of dividers are described in US 1.909.734, US 2.01 1.161 , US 4.251.005. US 4.789.170 describe circular shaped, disc baffles that are secured within a tank on a water truck that are designed to attenuate forces directed at them.

US 4.61 1.724 discloses a tank truck comprising a tank, whose shell is supported by a baffle. The vertical cross section of the baffle is straight, but its horizontal cross section has two concave sections and a convex section. Horizontal ribs are secured to the face of the baffle and help it to maintain the desired cross-sectional shape.

US 4.775.070 discloses a system for preventing fluid surges in fluid transport vehicles, where an internal baffle system comprises a plurality of upper stationary baffles spaced along the top interior wall portion of the tank and extending downward to a point within the tank, a second plurality of stationary baffles along the bottom floor portion of the tank and extending upward into the tank, a floor portion positioned substantially along the central interior of the tank for isolating the tank into an upper fluid portion and a lower fluid portion along its length, the floor portion including a centrally located panel member rotatable between open and closed positions, wherein in the open position allows fluid flow between the upper tank portion and the lower tank portion, and in the closed position any fluid contained within the lower half of the tank would be isolated from fluid or space in the upper half of the tank, thus creating a lower center of gravity of the tank, thus creating a lower center of gravity of the tank of the fluid being transported, and at the same time preventing any movement of the fluid that would create a surge within the tank.

It is an object of the present invention to minimize and possibly alleviate one or more of the disadvantages of the prior art, or to provide a useful alternative.

The object is achieved with a tank according to the following independent claim, with additional embodiments set forth in the dependent claims.

A tank according to the present invention comprises an elongated and hollow vessel, where each end of the elongated and hollow vessel is closed by an end cap, where 2N bulkheads with a curved surface are arranged within the elongated and hollow vessel. The bulkheads within the elongated and hollow vessel are arranged such that a bulkhead nearest one end cap of the tank has a concave surface facing said end cap and a subsequent following bulkhead has a convex surface facing said end cap, any further bulkheads being arranged with alternating concave and convex surfaces facing said end cap, N being an integer from 1 to infinite.

The elongated and hollow vessel has a cylindrical form, but it can also be envisaged that the elongated and hollow vessel can have other forms, for instance an elliptical form, polygonal form, square-shaped or rectangular form or the like. The bulkheads arranged within the elongated and hollow vessel will have a corresponding form as the elongated and hollow vessel.

According to one aspect of the present invention, each of the bulkheads having a concave surface facing said end cap and a subsequent following bulkhead having a convex surface facing said end cap will form a pair of bulkheads. Centres in such a pair of bulkheads may be arranged to abut each other, but the centres in such a pair of bulkheads may also be arranged with a distance between them, where the distance, for instance, may be less than approximately 2-5% of a diameter of the elongated and hollow vessel.

According to an aspect of the present invention, each of the bulkheads having a convex surface facing said end cap and a subsequent following bulkhead having a concave surface facing said end cap will form a pair of bulkheads. Such pair of bulkheads may be arranged with a distance between them. The distance between such pair of bulkheads should preferably not be less than 5-25% of the tank diameter, when the distance is measured at the wall of the vessel.

Such pair of bulkheads may also be arranged in such a way that the distance between the centres of the pair of bulkheads is approximately the diameter of the elongated and hollow vessel.

How the different pairs of bulkheads should be arranged in relation to each other, will depend on several parameters, for instance the tank diameter, which fluid is to be contained in the tank, movements and loads the tank is subjected to etc. A person skilled in the art would know how the bulkheads are to be arranged and this is therefore not discussed further herein. According to an aspect of the present invention, the tank may also include one or more additional bulkheads arranged within the tank. Such additional bulkheads may have a different design than the bulkheads with the curved surface. Such additional bulkheads may for instance have a plain surface, a surface with a different curvature, having a smaller diameter etc.

A person skilled in the art would understand that each of the bulkheads and/or the additional bulkheads may have individual design with varying degree of curvature.

A centre of a bulkhead is defined to be the centre point of the bulkhead, when the bulkhead is seen from a frontal view.

According to an aspect of the present invention, each bulkhead and/or each additional bulkhead may be provided with at least one upper port and/or at least one lower port, in order to allow fluid flow between the different bulkheads and any additional bulkheads within the tank, and to allow feedthrough for pipes, conduits or the like arranged within the tank. Such upper port(s) will also serve to equalize the pressure in the tank on both sides of the bulkheads and/or additional bulkheads. The upper and/or lower ports are provided as openings or holes through the bulkheads or as recesses formed around the periphery of the bulkheads. Ports may be replaced by a pipe or pipes, the pipe or pipes being open, in order to allow the same functionality, i.e. to allow fluid flow between the different bulkheads and to allow feedthrough for pipes and for equalizing the pressure.

According to an aspect of the present invention, one or more of the bulkheads and/or additional bulkheads may be provided with only upper port(s) and no lower port(s), or be provided with only lower port(s) and no upper port(s).

The tank according to the present invention is in particular relevant for marine LNG fuel systems, but is also applicable in any other liquid containment for reducing the sloshing phenomenon, both on land and sea. A tank according to the present invention will reduce the movements of the liquid, reduce spray of liquid through the gas phase, and thereby reduce the pressure loss due to sloshing phenomenon. In addition, the bulkheads serve to fulfil the requirements regarding strength of the tank due to static and dynamic loads.

According to one aspect, the tank according to the present invention may be used in a marine LNG fuel system. One such LNG fuel system may comprise a tank for storage of LNG, process equipment for vaporizing the LNG, and heating and pressurising the natural gas to a temperature and a pressure required by the engine, and feeding the required gas mass flow to the engine. The LNG fuel system may also comprise one or more process control and safety systems, where such system(s) will monitor and control the process. A ship may have one or several LNG tanks. The LNG tanks may be connected to each other by pipelines in the liquid and/or gas phases. Each LNG tank may have one or more process system(s) connected to it, and such process systems may be interconnected.

The process equipment may comprise one or more of the following elements and/or components: pump(s), vaporizer(s), super heater(s), pressure build-up unit(s) etc., where the different elements are interconnected to be able to process the LNG. The present invention is also applicable in LNG fuel systems without pump, and more general in storage tanks for other liquids than LNG, both atmospheric and pressurised tanks.

The invention will now be explained with reference to the attached figures where;

Figures 1A- 1B illustrate a first and second embodiment of a tank according to the present invention,

Figures 2A-2F illustrate a bulkhead arranged within the embodiments of the tank shown in figures 1A- 1B, seen from the front, and

Figure 3 shows a tank according to figures 1A- 1B as a component of a schematically illustrated LNG fuel system arranged on board a vessel.

Figures 1A- 1B illustrate a first and second embodiment of a tank 1 according to the present invention, where the tank 1 , for instance, may be a component in a marine LNG fuel system on board a vessel V (see figure 3). The tank 1 comprises an elongated and hollow vessel 2, where each end of the elongated and hollow vessel 2 is terminated by an end cap 31 , 32, thereby forming a closed tank 1. Inside the elongated and hollow vessel 2 are arranged 2N bulkheads 4a, 4b, the bulkheads 4a, 4b having curved surfaces. A bulkhead 4a, 4b nearest one end cap 31 , 32 is arranged in such a way that the bulkhead will have a convex surface facing said end cap 31 , 32, while a subsequent following bulkhead 4b, 4a will be arranged to have a convex surface facing said end cap 31 , 32. Any further bulkheads 4a, 4b are arranged with alternating concave and convex surfaces facing said end cap 31 , 32, with an increasing distance to said end cap 31 , 32.

Denotation N is an integer from 1 to infinite. If for instance N is chosen to be 1 , then the tank 1 comprises two such bulkheads 4a, 4b arranged within the tank 1. If for instance N is chosen to be 2, then four such bulkheads 4a, 4b are arranged within the tank 1.

In the embodiment shown in figure 1A, the bulkhead nearest one end cap having a concave surface facing the end cap and the subsequent following bulkhead having a convex surface facing the end cap will form a pair of bulkheads, where these two bulkheads are arranged such that centres C of the two bulkheads abut against each other. Similarly, each of the remaining bulkheads having a concave surface facing the end cap and a subsequent following bulkhead having a convex surface facing the end cap will form a pair of bulkheads, where also each of these pairs are arranged with the centres C abutting against each other.

A centre C of a bulkhead 4a, 4b is defined to be the centre point of the bulkhead 4a, 4b, when the bulkhead 4a, 4b is seen from a frontal view.

Furthermore, a first bulkhead having a convex surface facing the end cap and a subsequent following bulkhead having a concave surface facing the end cap will form a pair of bulkheads, where these two bulkheads are arranged such that a distance di between the centres C is approximately the diameter of the elongated and hollow vessel 2. A distance D between the pair of bulkheads is preferably not less than 10% of the diameter of the elongated and hollow vessel 2, when the distance D is measured at the wall of the elongated and hollow vessel 2.

One or more additional bulkheads 15 (only one is shown in this embodiment) may further be arranged within the tank 1 , where this additional bulkhead 15 has a different design than the bulkheads 4a, 4b, for instance, in the form of a plain plate.

In the embodiment shown in figure IB, the bulkhead nearest one end cap 31 , 32 having a concave surface facing the end cap 31 , 32 and the subsequent following bulkhead having a convex surface facing the end cap 3 1 , 32 will form a pair of bulkheads, where these two bulkheads are arranged such that centres C of the two bulkheads are spaced by a distance d2. Similarly, each of the remaining bulkheads having a concave surface facing the end cap and a subsequent following bulkhead having a convex surface facing the end cap will form a pair of bulkheads, where also each of these pairs are arranged with the centres C of the two bulkheads spaced with a distance d₂.

Similarly, as described in accordance with the first embodiment of the LNG tank 1 , the bulkheads having a convex surface facing the end cap and a subsequent following bulkhead having a concave surface facing the end cap may be arranged such that a distance di between the centres C is approximately the diameter of the elongated and hollow vessel 2.

A person skilled in the art will know that the bulkheads 4a, 4b, the additional bulkheads 15 and the end caps 31 , 32 can be connected and affixed to the elongated and hollow vessel 2 in many different ways, whereby this is not further described herein.

The elongated and hollow vessel 2 may have different forms, for instance a cylindrical form, an elliptical, a polygonal, a square-shaped or rectangular form or the like.

Figures 2A-2F show different designs of the bulkheads 4a, 4b and/or additional bulkheads 15, where it can be seen that each bulkhead 4a, 4b is provided with one or more upper ports 5 and one or more lower ports 6, only upper port(s) 5, only lower port(s) 6, this depending on pipes or conduits, supports and/or equipment within the LNG tank 1. Such upper and lower ports 5, 6 may be provided as openings or holes through the bulkheads or as recesses formed around the periphery of the bulkheads 4a, 4b and/or additional bulkhead(s) 15. However, the port may be replaced by pipe or pipes with opening to allow for the same functionality.

A possible use of each and one of the embodiments of the LNG tank 1 according to the present invention, as illustrated in figures 1A- 1B, is shown schematically in figure 3. The LNG tank 1 is then arranged in a LNG fuel system S arranged on board a vessel V, where the LNG fuel system S through pipelines or conduits 10 is connected to a combustion engine 1 1 , which combustion engine 1 1 in turn is connected to an electric generator and/or gearbox 13 and/or shaft 14 and at least one propeller 12.

The LNG fuel system S may, for instance, comprise at least one LNG tank 1 , for storage of LNG, process equipment E for vaporizing the LNG, and heating and pressurising the natural gas to the temperature and pressure required by the combustion engine 1 1 , and feeding the required gas mass flow to the combustion engine 1 1. A process control and safety system (not shown) monitors and controls the process.

Furthermore, as can be seen, the vessel V may have one or several LNG tanks 1. The LNG tanks 1 may be connected to each other by pipelines or conduits (not shown), thereby providing a fluid communication between the LNG tanks 1 for the liquid and/or gas phases of the tanks. Furthermore, each LNG tank 1 may have one or more process systems connected to it, and such process systems may furthermore be interconnected.

The present invention has now been explained with reference to embodiments, but a person skilled in the art will understand that changes and modifications will be able to be made to these embodiments which lie within the scope of the invention as defined in the following claims.

Claims

A tank (1) comprising an elongated and hollow vessel (2), each end (21 , 22) of the vessel (2) being closed by an end cap (3 1 , 32), 2N bulkheads (4a, 4b) with curved surfaces being arranged within the vessel (2), characterized in that a bulkhead (4a, 4b) nearest one end cap (31 , 32) of the tank (1) has a concave surface facing said end cap (3 1 , 32), and a subsequent following bulkhead (4b, 4a) has a convex surface facing said end cap (31 , 32), any further bulkheads (4a, 4b) being arranged with alternating concave and convex surfaces facing said end cap (31 , 32), N being an integer from 1 to infinite.

Tank according to claim 1 , characterized in that the elongated and hollow vessel (2) has a substantially cylindrical form.

Tank according to any one of claims 1 -2, characterized in that each of the bulkhead (4a) having a concave surface facing said end cap (31 , 32) and a subsequent following bulkhead (4b) having a convex surface facing said end cap (3 1 , 32) form a pair of bulkheads (4a, 4b), where centers (C) in such a pair of bulkheads are abutting each other or being nearby each other.

Tank according to any one of claims 1 -3, characterized in that each of the bulkhead (4b) having a convex surface facing said end cap (31 , 32) and a subsequent following bulkhead (4a) having a concave surface facing said end cap (31 , 32) form a pair of bulkheads (4b, 4a), where a distance (D) between such pairs of bulkheads (4b, 4a) preferably is not less than 10% or more of a diameter of the elongated and hollow vessel (2).

Tank according to claim 4, characterized in that a distance (dl) between centers (C) in such a pair of bulkheads (4b, 4a) approximately is the diameter of the elongated and hollow vessel (2).

Tank according to any one of the preceding claims 1 -5, characterized in that at least one additional bulkheads (15) is arranged within the tank (1), the at least one additional bulkheads (15) having a different design than the bulkheads (4a, 4b).

Tank according to any one of the preceding claims 1 -6, characterized in that at least one bulkhead (4a, 4b) is provided with at least one upper port (5) and/or at least one lower port (6).

Tank according to any one of the preceding claim 1 -6, characterized in that each of the bulkheads (4a, 4b) are provided with at least one lower port (6).

Tank according to claim 1 -5, characterized in that each of the bulkheads (4a, 4b) are provided with at least one upper port (5).

10. Tank according to any one of the preceding claims 1 -9, characterized in that the tank is arranged vertically, or at any angle between horizontal and vertical.

11. Tank according to any one of the preceding claims 1-10, characterized in that the bulkheads (4a, 4b) have the same or individual design with varying degree of curvature.

12. Use of a tank according to any one of claims 1-11, for use on board a vessel.

13. Use of a tank according to any one of claims 1-11 for storage of LNG.

14. A LNG fuel system (S) comprising at least one tank according to any one of claims 1-11, the LNG fuel system (S) further comprising process equipment (E) and a process control and safety system.