Marine transportation vessel

Abstract

The invention concerns a marine transportation vessel (1) for transportation of large, heavy and bulky cargo, wherein the vessel (1) comprises: an upwardly extending superstructure (2) fixed to the vessel (1) in a forward part (3) of the vessel (1); a substantially flat deck (4) configured to carry the cargo; a system for vessel propulsion comprising a propeller (5) and an internal combustion engine (6) operatively connected to the propeller via a propeller shaft (7); wherein both the internal combustion engine (6) and the propeller (5) are arranged in an aft part (8) of the vessel (1), and wherein an exhaust duct for guiding exhaust gas away from the internal combustion engine (6) comprises two or more separate exhaust sub-ducts (10a, 10b) arranged on top of each other so as to extend together with an air duct (12) through a narrow tunnel (18) between ballast tanks (23) in a longitudinal direction of the vessel (1) between the internal combustion engine (6) and the forward part (3) of the vessel (1).

Description

[0001] Marine transportation vessel

[0002] TECHNICAL FIELD

[0003] This invention relates to a marine transportation vessel for transportation of large, heavy and bulky cargo, such as offshore wind foundations, floating wind power hull structures, oil & gas structures, etc.

[0004] BACKGROUND OF THE INVENTION

[0005] There is an increased demand for marine transportation of large, heavy and bulky cargo, such as offshore wind foundations (including monopiles, jackets and floating foundations), floating wind power hull structures, oil & gas structures, etc. Marine transportation vessels, or heavy transport vessels (HTVs), for such purposes include semi-submersible vessels provided with ballast tanks making them capable of being lowered below the surface level (except the upper part of stabilizing superstructures and caissons) and then lifted so as to place equipment floating at the surface above the marine vessel onto a deck of the vessel. Unloading is then typically carried out by lowering the vessel and allowing the equipment to float off. For equipment loaded from a quay / wharf, either by rolling / skidding onboard or by lifting, also nonsubmersible deck cargo carriers may be used. Commonly, purpose-built marine transportation vessels of the type discussed here have a superstructure, holding e.g. accommodation and bridge of the vessel, arranged in a forward part of the vessel and, extending aftwards of the superstructure, an upper, open and substantially flat deck, sometimes denoted weather deck, substantially free from any bulwarks or obstructions for carrying the cargo. The deck may also extend aside of or even in front of the superstructure depending on the exact design and location of the superstructure. The length of this type of vessels is typically in the range 150- 250 m.

[0006] Although a variety of marine transportation vessels has been presented over the years there is still a need for improvements regarding both function and cost efficiency, for instance to allow for more cost efficient propulsion arrangements with lower environmental impact without compromising the cargo carrying flexibility.

[0007] SUMMARY OF THE INVENTION

[0008] The invention concerns a marine transportation vessel for transportation of large, heavy and bulky cargo, such as offshore wind foundations, floating wind power hull structures, oil & gas structures, etc. The vessel comprises: an upwardly extending superstructure fixed to the vessel in a forward part of the vessel; a substantially flat deck configured to carry the cargo, wherein the deck extends at least aftwards of the superstructure; and a system for vessel propulsion comprising a propeller and an internal combustion engine operatively connected to the propeller via a propeller shaft.

[0009] The vessel is of a semi-submersible type and further comprises: one or more controllable ballast tanks that can be filled with water and / or air and that are configured to allow the vessel to be lowered to a first level where the deck is located below a water surface level and lift the vessel to a second level where the deck is located above the water surface level.

[0010] Both the internal combustion engine and the propeller are arranged in an aft part of the vessel, and an exhaust duct for guiding exhaust gas away from the internal combustion engine is arranged to extend in a longitudinal direction of the vessel, inside a hull of the vessel below the deck, between the internal combustion engine and the forward part of the vessel and further to an exhaust gas outlet arranged in connection with the fixed superstructure.

[0011] The exhaust duct comprises two or more separate exhaust sub-ducts arranged on top of each other, and the two or more separate exhaust ducts are arranged in a tunnel that extends longitudinally inside the vessel. An air duct for guiding intake air to the internal combustion engine, and / or for guiding ventilation air to an enclosed engine room in which the internal combustion engine is arranged, is arranged to extend in the tunnel between the internal combustion engine and the forward part of the vessel and further to an air inlet arranged in connection with the fixed superstructure.

[0012] The tunnel has a narrow shape with a width less than a height thereof, and the tunnel is surrounded, at least at its sides, by ballast tanks that extend along the sides of tunnel.

[0013] In short, the marine transportation vessel of this disclosure allows for using an efficient and reliable propulsion system while at the same providing a high cargo capacity and loading flexibility since the need for a fixed exhaust funnel in the aft part is dispensed with. Moreover, a solution is provided for how to arrange such a long exhaust duct (and air duct) without taking too much space from the ballast tanks (see also below).

[0014] The engine drives the propeller directly via a propeller shaft that can be relatively short since both the engine and the propeller are located in the aft part of the vessel. At the same time, the vessel of this disclosure provides for using the fixed superstructure in the forward part of the vessel as a funnel for exhaust gases and thus dispenses with the need to release the exhaust gas via a fixed tower / funnel / caisson located in the aft part of the vessel.

[0015] A vessel of the type discussed here may instead be provided with a dieselelectric propulsion system where a diesel engine located in the forward part of the vessel generates electricity to an electric motor arranged in the aft part of the vessel for driving of the propeller. This allows for arranging the exhaust duct more or less straight up to and through the superstructure. However, such a diesel-electric propulsion system is associated with efficiency losses of around 10% compared to around 2-3% for a mechanical system where the engine drives the propeller via a propeller shaft. Another alternative may be to arrange a very long propeller shaft, maybe 100-200 m for this type of vessel, between an engine in the forward part of the vessel and the propeller at the stem, but such a long propeller shaft is challenging to install and align and challenging to use due to deflections of the vessel in waves and the risk for various vibrational issues.

[0016] As mentioned above, expelling the exhaust gas via the superstructure in the forward part of the vessel dispenses with the need to release the exhaust gas via a tower or funnel located in the aft part of the vessel. This means that a vessel according to this disclosure can be provided with an efficient propulsion system in the aft part while still being provided with a substantially flat cargo deck that extends over the entire length and width of the vessel except for where the fixed superstructure is located, i.e. without any tower / funnel located in the aft part of the vessel. For a semi-submersible transport vessel, that normally is provided with starboard side and port side stabilizing caissons / towers at the most aft portion of the deck, it means that both caissons / towers may be arranged to be detachable so as to facilitate loading (or unloading) and to allow cargos to extend over the aft end and / or the sides of the vessel. This is not possible, or is at least more complicated, if one or both caissons are arranged in a permanent manner and / or also function as funnels or at least support the exhaust duct.

[0017] The absence of towers / funnels / caissons in the aft part improves the loading capacity of the vessel since the entire aft part of the deck now becomes available for loading, and mono piles or other equipment loaded onto the deck may even extend at least partly outside of the deck in the aft part of the vessel. For instance, five mono piles, each with a diameter of 10 m, may be loaded longitudinally side by side with 1 m space between onto a vessel having a width / breadth of 48 m (5 x 0lO m + 4 x 1 m space = 54 m; 3 m over-projection on each side). The absence of caissons / funnels in the aft part also simplifies the loading procedure where the equipment to be loaded has a large width and is loaded onto the vessel from e.g. a wharf / quay onto the vessel towards the stern thereof, i.e. when the vessel has its stem facing the quay and where the cargo may be rolled, skidded or lifted onto the deck. The caissons may or may not be re-mounted onto the vessel after loading depending on how the cargo is to be unloaded from the vessel after transport. (In case the equipment is to be unloaded by submerging the vessel, room has been provided in the aft part of the vessel for re-mounting of the caissons).

[0018] The deck forms an upper, open deck and that it is substantially flat means, for instance, that there are no permanent bulwarks or other permanent obstructions at the aft or along the sides of the vessel. The deck typically extends over the entire upper side of the vessel except where the superstructure(s) and any detachable caissons are located.

[0019] The marine transportation vessel of this disclosure has a high propulsion efficiency, and thus a reduced environmental impact, while at the same time provides for improved loading capabilities.

[0020] That the exhaust duct comprises two or more separate exhaust sub-ducts arranged on top of each other reduces the space required for the exhaust duct in the sideways direction of the vessel (since one large duct with e.g. a circular cross-section is wider than vertically arranged sub-ducts having the same cross-sectional shape and a total cross-sectional area similar to that of the large duct). This is of particular interest for a vessel of the semi-submersible type where the space taken from the ballast tanks should be minimized since there is typically a challenge to set that type of vessel in the lower position below the water surface and therefore the total ballast volume should be as large as possible. The arrangement with sub-ducts positioned on top of each other has a particular advantage when the exhaust system has an unusually long length as in the present invention. When an exhaust pipe gets very long, the backpressure might increase to a level that may become a challenge for the engine. To reduce the back-pressure, one may increase the diameter (cross-sectional area) of the exhaust pipe. So, in a vessel of the inventive type, the total area of the exhaust duct(s) will be larger than conventionally used in vessels of similar type. The above explained advantageous effect of providing two or more exhaust ducts on top of each other is thus enhanced.

[0021] Exhaust ducts may get very hot and to prevent direct contact with the ballast tanks, which could lead to evaporation of the ballast water, the exhaust subducts are arranged in a narrow tunnel that extends between the ballast tanks. A further advantage of the tunnel is that it also is adapted supply intake and ventilation air to the engine and the engine room. The air duct may be arranged as a separate duct located in the tunnel or a delimited section of the tunnel may form the air duct.

[0022] The tunnel may be surrounded not only by its sides but also above and below by ballast tanks that extend along the tunnel.

[0023] In an embodiment of the invention, the tunnel is divided into a plurality of separated sections located at different vertical levels. The exhaust sub-ducts may be located in a first section and the air duct in a second section. The subducts may alternatively be located in separate sections.

[0024] In an example, the tunnel may comprise three sections where the exhaust subducts are arranged in the uppermost of these sections, where the air duct is arranged below the exhaust duct section, and where a lower section forms a walking passage for vessel staff. Return air from the engine room may be guided through the section where the exhaust ducts are located. In an embodiment of the invention, the forward part of the vessel forms 40% or less, preferably 25% or less, of a total length of the vessel.

[0025] In an embodiment of the invention, the aft part of the vessel forms 40% or less, preferably 25% or less, of a total length of the vessel.

[0026] In an embodiment of the invention, each exhaust sub-duct has a cross section exhibiting a width that is less than a height thereof. This can be used for further reducing the space required for the exhaust duct (and the tunnel) in the sideways direction of the vessel.

[0027] In an embodiment of the invention, no funnels, permanent caissons or other permanent upwardly extending structures of similar type are arranged onto the deck aft of the superstructure.

[0028] In an embodiment of the invention, the vessel comprises: first and second stability caissons arranged on opposite sides of the vessel in the aft part thereof, wherein the stability caissons and the superstructure provide for stability of the vessel when set at the first, lower level, wherein both the first and the second stability caissons are arranged to be detachable and re- attachable to the vessel.

[0029] In an embodiment of the invention, the internal combustion engine is a dualfuel engine, such as an oil / gas engine or an oil / methanol engine.

[0030] In an embodiment of the invention, the deck substantially covers an entire upper side of the vessel except for the fixed superstructure and any detachable caissons.

[0031] In an embodiment of the invention, the exhaust gas outlet is arranged at an upper part of the fixed superstructure. In an embodiment of the invention, a total length of the vessel is at least 100 m, or at least 150 m.

[0032] BRIEF DESCRIPTION OF DRAWINGS

[0033] In the description of the invention given below reference is made to the following figure, in which:

[0034] Figure 1 shows a schematic sectional side view of an example of a marine transportation vessel according to this disclosure.

[0035] Figure 2 shows a mid-ship cross section of the vessel of figure 1 .

[0036] Figure 3 shows a further example of a marine transportation vessel according to this disclosure.

[0037] Figure 4 shows a still further example of a marine transportation vessel according to this disclosure.

[0038] Figure 5 shows a cross section of an example of a tunnel used for housing e.g. an exhaust duct.

[0039] DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0040] Figure 1 shows a schematic sectional side view of an example of a marine transportation vessel 1 , in this case a semi-submersible vessel, for transportation of large, heavy and bulky cargo, such as offshore wind foundations, floating wind power hull structures, oil & gas structures, etc. Figure 2 shows a mid-ship cross section of the vessel of figure 1 .

[0041] As shown in figures 1 and 2, the vessel 1 comprises a hull 9, a forward part 3, an aft part 8, a weather deck 4, an upwardly extending superstructure 2 fixed to the vessel 1 in the forward part 3, and first and second detachable stabilizing caisson 22 (of which only one is shown in figure 1 ). The deck 4 is substantially flat and extends aftwards of the superstructure 2 that in this example is located at the forward end of the forward part 3 of the vessel.

[0042] A system for vessel propulsion comprises a starboard side propeller 5 and a starboard side internal combustion engine 6 operatively connected to the starboard side propeller via a starboard side propeller shaft 7. The propulsion system comprises also a port side set of propeller, propeller shaft and engine (not shown) arranged in a similar way as the starboard side set. Both the internal combustion engine 6 and the propeller 5 are arranged in an aft part 8 of the vessel 1 . The engine 6 is arranged in an engine room 14.

[0043] As shown in figure 2, the vessel 1 is provided with a plurality of controllable ballast tanks 23 that can be filled water and / or air and that are configured to allow the vessel 1 to be lowered to a first level where the deck 4 is located below a water surface level and lift the vessel 1 to a second level where the deck 4 is located above the water surface level.

[0044] The first and second stability caissons 21 , 22 are arranged on opposite sides of the vessel 1 in the aft part 8 thereof (see also figure 3). The stability caissons 21 , 22 together with the superstructure 2 provide for stability of the vessel 1 when submerged. Both the first and the second stability caissons 21 , 22 are arranged to be detachable from, and re-attachable to, the vessel 1 , which is possible because none of them is used for exhaust gas funnels.

[0045] An exhaust duct 10 in the form of exhaust sub-ducts 10a, 10b, for guiding exhaust gas away from the internal combustion engine 6 is / are arranged to extend in a longitudinal direction of the vessel 1 , inside the hull 9 of the vessel 1 below the deck 4, between the internal combustion engine 6 and the forward part 3 of the vessel 1 and further to an exhaust gas outlet 11 arranged in an upper part of the fixed superstructure 2. Similar exhaust gas systems are arranged on both starboard and port sides of the vessel, i.e. each engine 6 is connected with a corresponding exhaust gas duct.

[0046] An air duct 12 for guiding intake air to the internal combustion engine 6 extends in a similar way as the exhaust duct 10. The air duct 12 extends in a longitudinal direction of the vessel 1 , inside the hull 9 of the vessel 1 below the deck 4, between the internal combustion engine 6 and the forward part 3 of the vessel 1 and further to an air inlet 15 arranged in connection with the fixed superstructure 2. In this example, air is fed via the air duct 12 to the engine room 14 and the engine 6 takes its intake air from the engine room 14. The air duct 12 is thus used to feed both engine intake air as well as ventilation air to the engine room 14.

[0047] As indicated in figures 1 and 2, both the exhaust sub-ducts 10a, 10b as well as the air duct 12 are arranged in a tunnel 18 that extends longitudinally inside the vessel 1. Figure 2 shows that the two separate exhaust sub-ducts or exhaust pipes 10a, 10b are arranged on top of each other. This reduces the required width of the tunnel 18 and thereby leaves more room for larger ballast tanks 23.

[0048] Figure 3 shows a further example of a marine transportation vessel 1 according to this disclosure. The vessel of figure 3 is very similar to that of figures 1 -2 and the same reference numbers have been used. Figure 3 shows clearly, for instance the detachable caissons 21 , 22 and the propellers 5, exhaust outlets 11 and air inlets 15 located on both starboard and port sides of the vessel 1 .

[0049] Figure 4 shows a still further example of a marine transportation vessel 1 according to this disclosure. The vessel 1 of figure 4 can be seen as a representation of both the vessel 1 of figure 3 (and figures 1-2) with the caissons 21 , 22 detached.

[0050] Figure 5 shows a cross section of an example of the tunnel 18 used for housing e.g. the exhaust duct 10. As shown in figure 5, the tunnel 18 has a narrow shape with a width less than a height thereof, and the tunnel 18 is divided into a plurality of separated sections 18a, 18b, 18c located at different vertical levels. The separate exhaust sub-ducts / pipes 10a, 10b are located in a first (upper) section 18a and a second (middle) section 18b forms the air duct 12. A third (lower) section 18c forms a passageway for vessel staff 30. Return air from the engine room 14 is fed through the upper section 18a in the space surrounding the exhaust sub-ducts / pipes 10a, 10b.

[0051] The invention is not limited by the embodiments described above but can be modified in various ways within the scope of the claims.

Claims

CLAIMS1. A marine transportation vessel (1 ) for transportation of large, heavy and bulky cargo, such as offshore wind foundations, floating wind power hull structures, oil & gas structures, etc., wherein the vessel (1 ) comprises:- an upwardly extending superstructure (2) fixed to the vessel (1 ) in a forward part (3) of the vessel (1 );- a substantially flat deck (4) configured to carry the cargo, wherein the deck extends at least aftwards of the superstructure (2);- a system for vessel propulsion comprising a propeller (5) and an internal combustion engine (6) operatively connected to the propeller via a propeller shaft (7); wherein the vessel (1 ) is of a semi-submersible type and comprises:- one or more controllable ballast tanks (23) that can be filled with water and / or air and that are configured to allow the vessel (1 ) to be lowered to a first level where the deck (4) is located below a water surface level and lift the vessel (1 ) to a second level where the deck (4) is located above the water surface level; wherein both the internal combustion engine (6) and the propeller (5) are arranged in an aft part (8) of the vessel (1 ), wherein an exhaust duct (10, 10a, 10b) for guiding exhaust gas away from the internal combustion engine (6) is arranged to extend in a longitudinal direction of the vessel (1 ), inside a hull (9) of the vessel (1 ) below the deck (4), between the internal combustion engine (6) and the forward part (3) of the vessel (1 ) and further to an exhaust gas outlet (11 ) arranged in connection with the fixed superstructure (2), wherein the exhaust duct (10) comprises two or more separate exhaust subducts (10a, 10b) arranged on top of each other, wherein the two or more separate exhaust ducts (10a, 10b) are arranged in a tunnel (18) that extends longitudinally inside the vessel (1 ), wherein an air duct (12) for guiding intake air to the internal combustion engine (6), and / or for guiding ventilation air to an enclosed engine room (14) in whichthe internal combustion engine (6) is arranged, is arranged to extend in the tunnel (18) between the internal combustion engine (6) and the forward part (3) of the vessel (1 ) and further to an air inlet (15) arranged in connection with the fixed superstructure (2), wherein the tunnel (18) has a narrow shape with a width less than a height thereof, and wherein the tunnel (18) is surrounded, at least at its sides, by ballast tanks (23) that extend along the sides of tunnel (18).

2. The marine transportation vessel (1 ) according to claim 1 , wherein the forward part (3) of the vessel (1 ) forms 40% or less, preferably 25% or less, of a total length of the vessel (1 ).

3. The marine transportation vessel (1 ) according to claim 1 or 2, wherein the aft part (8) of the vessel (1 ) forms 40% or less, preferably 25% or less, of a total length of the vessel (1 ).

4. The marine transportation vessel (1 ) according to any of the above claims, wherein each exhaust sub-duct (10a, 10b) has a cross section exhibiting a width that is less than a height thereof.

5. The marine transportation vessel (1 ) according to claim 1 , wherein the tunnel (18) is divided into a plurality of separated sections (18a, 18b, 18c) located at different vertical levels, wherein the exhaust duct (10a, 10b) is located in a first section (18a) and wherein the air duct (12) is located in a second section (18b).

6. The marine transportation vessel (1 ) according to any of the above claims, wherein no funnels, permanent caissons or other permanent upwardly extending structures of similar type are arranged onto the deck (4) aft of the superstructure (2).

7. The marine transportation vessel (1 ) according to any of the above claims, wherein the vessel (1 ) comprises first and second stability caissons (21 , 22) arranged on opposite sides of the vessel (1 ) in the aft part (8) thereof, wherein the stability caissons (21 , 22) and the superstructure (2) provide for stability of the vessel (1 ) when set at the first, lower level, wherein both the first and the second stability caissons (21 , 22) are arranged to be detachable from and re- attachable to the vessel (1 ).

8. The marine transportation vessel (1 ) according to any of the above claims, wherein the internal combustion engine (6) is a dual-fuel engine, such as an oil / gas engine or an oil / methanol engine.

9. The marine transportation vessel (1 ) according to any of the above claims, wherein the deck (4) substantially covers an entire upper side of the vessel (1 ) except for the fixed superstructure (2) and any detachable caissons (21 , 22).

10. The marine transportation vessel (1 ) according to any of the above claims, wherein the exhaust gas outlet (11 ) is arranged at an upper part of the fixed superstructure (2).11 . The marine transportation vessel (1 ) according to any of the above claims, wherein a total length of the vessel (1 ) is at least 100 m, or at least 150 m.

12. The marine transportation vessel (1 ) according to any of the above claims, wherein the deck (4) is arranged without any obstructions and / or permanent bulwarks along the sides and at the aft end to allow transport of cargo that extends over the sides and / or aft of the vessel (1 ).

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