阅读说明：本技术 排气桅杆 (Exhaust mast ) 是由 洛朗·斯佩塔尔 西尔维斯特·皮尔提耶 皮埃尔·豪尔 于 2018-10-22 设计创作，主要内容包括：一种用于船舶的排气桅杆(1),其中所述桅杆(1)具有一桅杆本体(2)和设置在所述桅杆本体(2)的一端的一桅杆头(3),所述桅杆本体(2)和所述桅杆头(3)均呈中空管状结构,所述桅杆本体和所述桅杆头均有侧壁(4,5),所述桅杆头(3)的下部与所述桅杆本体(2)相连接,所述桅杆头(3)的上部具有一开口(10),所述桅杆本体(2)的上端部通过所述桅杆头(3)的下端接合所述桅杆头(3)的内部空间,所述桅杆本体(2)的上端部的外部横截面小于所述桅杆头(3)的下部的内部横截面,所述桅杆头(3)还包括：-一引水系统(13,14),通过组装元件(15)固定到所述桅杆头(3)上,并在桅杆的纵向方向上与所述开口(10)相对,-一外围连接板(16),布置在所述桅杆本体(2)的上端部的外表面与所述桅杆头的下部的内表面之间,该外围连接板(16)具有至少一个穿孔。(An exhaust mast (1) for a ship, wherein the mast (1) has a mast body (2) and a mast head (3) arranged at one end of the mast body (2), the mast body (2) and the mast head (3) each having a hollow tubular structure, the mast body and the mast head each having side walls (4,5), a lower portion of the mast head (3) being connected with the mast body (2), an upper portion of the mast head (3) having an opening (10), an upper end of the mast body (2) engaging an inner space of the mast head (3) through a lower end of the mast head (3), an outer cross-section of the upper end of the mast body (2) being smaller than an inner cross-section of the lower portion of the mast head (3), the mast head (3) further comprising: -a water diversion system (13,14) fixed to the mast head (3) by means of assembly elements (15) and opposite the opening (10) in the longitudinal direction of the mast, -a peripheral connection plate (16) arranged between the outer surface of the upper end of the mast body (2) and the inner surface of the lower part of the mast head, which peripheral connection plate (16) has at least one perforation.)

1. An exhaust mast (1) for a vessel (70), characterized in that the mast (1) has a mast body (2) and a mast head (3) arranged at one end of the mast body (2), the mast body (2) and the mast head (3) are both hollow tubular structures, the mast body and the mast head are both provided with side walls (4,5), the lower part of the mast head (3) is connected with the mast body (2), the upper part of the mast head (3) has an opening (10) which can discharge gas, the upper end of the mast body (2) is joined to the inner space of the mast head (3) via the lower end of the mast head (3), the outer cross section of the upper end of the mast body (2) is smaller than the inner cross section of the lower part of the mast head (3), the mast head (3) further comprising:

-a water diversion system (12) fixed to the mast head (3) by means of assembly elements (15), which water diversion system is opposite to the opening (10) in the longitudinal direction of the mast, to lead water in the longitudinal direction of the mast towards or away from the opening of the mast body (2),

-a peripheral connection plate (16) arranged between the outer surface of the upper end of the mast body (2) and the inner surface of the lower part of the mast to collect the residual water flow on the inner surface of the mast head (3), the peripheral connection plate (16) having at least one through hole (17) designed to discharge the residual water flow from the mast.

2. An exhaust mast (1) according to claim 1, characterized in that the lower side wall of the mast head (3) and the connection plate (16) form a drainage gutter (11), which drainage gutter (11) surrounds the upper end of the mast body (2).

3. An exhaust mast (1) according to claim 1 or 2, characterized in that the water diversion system (12) is arranged inside or outside the mast head (3) and that the water diversion system (12) has a water recovery device (13), preferably in the form of a funnel, and a drainage device (14), preferably in the form of a tube, so that the recovery device (13) can be emptied outside the mast head (3).

4. An exhaust mast (1) according to claim 1 or 2, characterized in that the priming system (12) is located above or below the opening (10) and remote from the opening (10), the priming system (12) having an outer cross section larger than the cross section of the opening (10), the priming system (12) preferably being dome plate shaped or conical.

5. An exhaust mast (1) according to one of the preceding claims, characterized in that the mast head (3) and the mast body (2) are fastened to each other using flat fastening supports (6) distributed over the entire inner surface of the mast head (3) and arranged between the inner surface of the mast head (3) and the outer surface of the mast body (2).

6. An exhaust mast according to claims 2 and 5, characterized in that the fastening support (6) is arranged parallel to the longitudinal direction of the mast, the fastening support (6) being designed to delimit different parts of a drain (11), fluid communication between the different parts of the drain (11) being ensured by support holes (7) formed in the fastening support (6).

7. An exhaust mast (1) according to claim 5 or 6, characterized in that there are eight fastening supports (6) in total.

8. An exhaust mast (1) according to one of the preceding claims, characterized in that the assembly element (15) is a flat bar, of which there are preferably eight flat bars, which are distributed around the entire inner surface of the mast head (3) and are oriented in parallel in the longitudinal direction of the mast.

9. An exhaust mast (1) according to one of the preceding claims, characterized in that the mast head (3) comprises a grating (18) which is arranged on the opening (10) in the upper part of the mast head (3) for filtering the water flowing to the opening (10).

10. An exhaust mast (1) according to any one of the preceding claims, characterized in that the mast head (3) has a lower opening parameter P determined by the following equation: -S1/S2, wherein S1 is the total surface area of said at least one perforation (17) in said peripheral connection plate (16) and S2 is the total surface area of the upper opening (10) of said mast head (3), said lower opening parameter P being such as to quantify the size of said lower opening with respect to the upper opening of said mast head (3), this parameter P being equal to or less than 0.01.

11. An exhaust mast (1) according to one of the preceding claims, characterized in that the mast head (3) has three peripheral connection plates (16) distributed around the entire mast head (3), each plate (16) having at least one through-hole (17), the plates being fastened to each other such that the lower side walls of the mast head (3) and the connection plates (16) form gutters (11) arranged around the upper end of the mast body (2).

12. Vessel (70) for transporting cooled liquid products, having a double hull (72), a storage tank (71) arranged in the double hull, and at least one air extraction mast (1) according to any of the preceding claims connected to the storage tank, which is located on an upper deck (81) of the vessel and which emits air to the atmosphere when the pressure in the storage tank is excessive.

Technical Field

The invention relates to the field of exhaust masts for storage facilities for liquefied gases, in particular liquefied natural gas. The invention relates in particular to a bleed mast for a liquefied gas transport vessel, such as an lng carrier.

Background

the liquefied natural gas is typically stored in tanks at a pressure near atmospheric pressure and at a temperature of about-163 ℃ in liquid form, and an lng carrier may house a plurality of GNL tanks.

Disclosure of Invention

The core idea of the invention is therefore to prevent rain or sea water from entering the mast interior by draining it clean at the mast head. In fact, since rain has a negative effect on the air extraction mast and its air extraction efficiency, means for directing water within the mast and/or drainage means, such as holes in the lower portion of the mast head, may be provided to drain any water that has entered the mast head.

However, considering that the gas may be discharged to the bottom of the storage facility, which may have an operator present, it is necessary to prevent the excessive gas from being discharged through these drainage means. An advantage of the present invention is that it effectively drains rain water at the mast head while limiting the risk of air draining from the mast head to the bottom of the storage facility where the operator is present.

According to one embodiment, the present invention provides an exhaust mast for a marine vessel, wherein the mast has a mast body and a mast head disposed at one end of the mast body, the mast body and the mast head each having a hollow tubular structure, the mast body and the mast head each having a side wall, a lower portion of the mast head being connected to the mast body, an upper portion of the mast head having an opening capable of exhausting gas, an upper end portion of the mast body engaging an interior space of the mast head through a lower end of the mast head, an outer cross-section of the upper end portion of the mast body being smaller than an inner cross-section of the lower portion of the mast head, the mast head further comprising:

A priming system fixed to the mast head by means of the assembly element, said priming system being opposite to said opening in the longitudinal direction of the mast to direct water in the longitudinal direction of the mast towards the opening remote from the mast body or away from the opening remote from the mast body,

-a peripheral web disposed between the outer surface of the upper end of the mast body and the inner surface of the lower portion of the mast head for collecting residual water flow on the inner surface of the mast head, the peripheral web having at least one through-hole configured to drain the residual water flow from the mast.

By using a drainage system and perforations in the web on the mast head, the exhaust mast can be made to vent gas efficiently while preventing rain water from entering the body of the mast. Furthermore, the peripheral connection plate has the advantage of limiting the open part of the lower part of the mast head, and thus the amount of gas that can be discharged through the lower part, which may be dangerous for operators working on the upper deck of a ship, for example.

First, the diversion system can divert the main water flow entering in the longitudinal direction of the opening of the mast head, preventing most of the rain water from entering the exhaust mast, thereby limiting or eliminating the need to drain the exhaust mast, which is expensive and complicated to operate. The invention thus makes it possible to avoid or at least limit this draining step, simplifying the maintenance of the mast.

Although the main flow is diverted from the interior of the mast by the priming system, there is a residual flow of rainwater which is not affected by the priming system but flows along the inner surface of the mast head, so that the system has a through-hole in the lower part of the mast head through which the residual flow can be removed from the mast.

Furthermore, it is advantageous to form perforations in the peripheral webs. In practice, during the evacuation of large amounts of air from the exhaust mast, there is a residual air flow along the path to the lower portion of the mast head. If too much airflow is discharged in this way, it will be dangerous for the operator, since it will flow towards the operator working under the mast. Therefore, it is advantageous to control the residual gas flow. The peripheral web can thus limit this residual gas flow by limiting the size of the perforations in the web.

Such a bleed mast may have one or more of the following features, according to embodiments.

According to one embodiment, the upper and lower portions of the mast head are shaped like truncated cones which converge and diverge in the direction of gas flow.

According to one embodiment, the mast head and the mast body are made of stainless steel.

According to one embodiment, the side walls of the lower portion of the mast head and the web form a gutter around the upper end of the mast body.

Thanks to these features, not only is the residual flow of water discharged from the gutter through the perforations, but the gutter can also contain a certain amount of water, which then acts as a reservoir, giving time for the water to be discharged from the perforations in the event of excess water. In fact, depending on the amount of water the gutter receives from the residual flow of water, it is possible that the perforations do not have the ability to drain immediately, and therefore the gutter has the ability to hold water in anticipation of draining through the perforations.

According to some embodiments, the priming system may be located inside or outside of the club head. According to one embodiment, the priming system has a water recovery device, preferably in the form of a funnel, and a drainage device, preferably in the form of a tube, so that the recovery device can be emptied out of the mast head.

According to one embodiment, the drainage means is inclined at a non-zero angle, preferably 15 °, with respect to the horizontal to enable water to drain from the recovery device.

When placed inside the mast head, the recovery device is effective to recover all water from the main water stream that has entered through the opening in the upper portion of the mast head. Furthermore, the funnel shape of the recovery device enables the device to naturally collect water in the center of the device to facilitate drainage. The water may then be drained from the mast head through a plumbing drain. The shape of the drain enables the water to be discharged hermetically while occupying a limited space in the mast head, which prevents the drain from interfering with the discharge of gas.

According to one embodiment, the diversion system is located above or below and away from the opening, the diversion system having an outer cross-section that is larger than the cross-section of the opening. The water diversion system is preferably dome plate shaped or conical.

The diversion system thus designed in this embodiment enables the system to direct the main flow of water to or from the opening. In fact, in this case, the system acts as a roof above or below the opening, preventing water from passing directly through the opening or preventing water that has passed through the opening from reaching the mast body.

According to one embodiment, the mast head and the mast body are fastened to each other using flat fastening supports distributed over the entire inner surface of the mast head and arranged between the inner surface of the mast head and the outer surface of the mast body.

These features enable the mast head and mast body to be securely fixed to each other using the support to ensure stability of the connection, thereby enabling the mast to withstand the forces experienced during use on a gas carrier. Furthermore, the fastening support may be fastened by welding to the mast head and the mast body.

According to one embodiment, the fastening support is arranged parallel to the longitudinal direction of the mast, the fastening support being designed to define different drain portions, fluid communication between the different drain portions being ensured by support holes formed in the fastening support.

Thus, the support holes prevent a drain portion of a given arrangement, which does not have perforations, from being filled with water without having to drain the water accumulated therein. In practice, the support holes then enable all portions to communicate with each other, and not all portions of the drain need to be perforated.

According to one embodiment, the support hole is located at a lower end of the fastening support.

According to one embodiment, there are eight fastening supports.

The distribution of the fastening supports allows the load and stress applied to each support to be shared, thereby extending the service life of the fastening supports and making the structure more stable.

According to one embodiment, the assembly element is a flat bar, wherein there are preferably eight flat bars distributed around the entire inner surface of the mast head and oriented in parallel along the longitudinal direction of the mast.

The distribution of the assembly elements allows the load and stress applied to each support to be shared, thus extending the useful life of the assembly elements and making the structure more stable. Furthermore, the flat bar shape parallel to the longitudinal direction has the advantage of minimizing the disturbance of the gas discharge by occupying a limited depth.

According to one embodiment, the mast head includes a grille disposed over an opening in an upper portion of the mast head to filter water flowing toward the opening.

The grate prevents any waste larger than the mesh of the grate from entering the exhaust mast. In addition, the grill also prevents flashback into the mast, which could damage the exhaust mast.

According to one embodiment, the mast head has a lower opening parameter P determined by the following equation: P-S1/S2, where S1 is the combined or total surface area of at least one perforation in the peripheral webs and S2 is the total surface area of the upper opening of the club head, a lower opening parameter P can quantify the size of the lower opening relative to the upper opening of the club head, the parameter P being equal to or less than 0.01.

According to one embodiment, the opening parameter P is equal to or less than 0.005.

Preferably, the total surface area S1 of the one or more perforations is equal to or greater than 0.5cm ²And the surface area S2 of the opening of the upper part of the mast head is equal to or larger than 150cm ²。

The lower opening parameter allows a clear quantification of how much smaller the opening in the lower part of the club head is than the opening in the upper part of the club head.

According to one embodiment, the mast head has three peripheral connection plates distributed around the entire mast head, each plate having at least one perforation, the plates being fastened to each other such that the side walls of the lower part of the mast head and the connection plates form a gutter arranged around the upper end of the mast body.

These features facilitate the assembly of the plates, as it is easier to assemble a plurality of connecting plates arranged on a portion of the profile of the mast body than to assemble a single massive plate around the entire mast body.

According to one embodiment, the invention also provides a vessel for transporting cooled liquid products, having a double hull, a storage tank arranged in the double hull and at least one exhaust mast according to the invention connected to the storage tank, which at least one mast is located on the upper deck of the vessel and exhausts gas to the atmosphere in case of an excessive pressure in the storage tank.

Drawings

The invention may be better understood, and other objects, details, features and advantages thereof more clearly elucidated by the following detailed description of several specific embodiments of the invention, given by way of non-limiting example only, with reference to the accompanying drawings.

FIG. 1 is a side view of a vessel equipped with liquefied natural gas and with a vented mast;

FIG. 2 is a top view of a mast head including a priming system according to a first embodiment;

3 FIG. 3 3 3 is 3 a 3 cross 3- 3 sectional 3 view 3 of 3 the 3 club 3 head 3 taken 3 along 3 plane 3 A 3- 3 A 3 in 3 FIG. 3 2 3; 3

FIG. 4 is a schematic view of a mast head including a priming system according to a second embodiment;

FIG. 5 is a front view of the assembled components;

FIG. 6 is a front view of a fastening support including a support hole;

FIG. 7 is a side view of a fastening support including a support hole;

FIG. 8 is a top view of a peripheral web having perforations;

FIG. 9 is a simulation of airflow in a bleed mast according to one embodiment; and

Fig. 10 is a schematic cross-sectional view of a tank of an lng carrier and a loading terminal of the tank, wherein a degassing mast is mounted on the vessel.

Detailed Description

In the description and claims, the terms "upper", "lower", "directly above" and "directly below" are to be understood with reference to the longitudinal direction of the mast and the direction of the mast body towards the mast head.

figure 1 shows a vessel 70 for transporting liquefied natural gas (GN L) having a plurality of storage tanks 71 mounted in the hull 72 of the vessel 70 the GN L stored in the tanks is continuously vaporized, thereby gradually increasing the pressure inside the storage tanks 71, which results in a liquid phase and a gaseous phase in the storage tanks.

To prevent damage to the tanks 71 and to avoid any risk of leakage, a pressure relief valve is installed on each tank 71. By default, the valve is closed and will open upon command of the valve controller only when the pressure within the tank exceeds a predetermined value. Some of the gas is then vented from the tank and can then be used by the ship's propulsion system or vented directly to the atmosphere through the masts 1, which masts 1 are mounted on the upper deck 81 of the ship 70 and connected to the tank 71 through pressure relief valves.

The exhaust mast comprises a mast body 2 and a mast head 3. The mast body 2 is formed by a hollow tubular structure having a body side wall 4. Similarly, the mast head is formed by a hollow tubular structure having a head side wall 5. The gas discharged through the exhaust mast then flows first through the mast body 2 and then through the mast head 3, the mast head 3 having an opening 10 to the atmosphere through which opening 10 the gas is discharged.

for safety reasons, the height of the exhaust mast 1 on the ship 70 carrying the GN L, e.g., an LNG carrier, or any GN L storage facility, should be sufficient to enable gas exhausted from the mast head 3 to leave the upper deck 70 or the ground, respectively.

In the event of rain, storm or any other condition that allows water to enter through the openings in the mast head 3, water will enter the interior of the exhaust mast 1. The ingress of water can cause several problems: firstly, the rainwater can form a pool inside the mast and prevent effective drainage of gases, secondly, the rainwater can damage the inside of the mast, and finally, the rainwater can require the mast to drain to remove the accumulated water, which is a more complex and costly operation. Therefore, means must be installed to prevent rain water from entering mast 1. These devices may be mounted directly on the mast head 3 in order to prevent water from entering the body of the mast 2 or penetrating further into the exhaust system connected to the tank.

According to a first embodiment, a mast 1, in particular a mast head 3, is shown in fig. 2 and 3, which show the different elements of the mast head 3. The mast head 3 consists of a lower part 8 and an upper part 9, which are frusto-conical. The two truncated cone shaped sections are assembled together at their ends of maximum diameter so that the diameter of the assembled club head is maximum with the upper and lower sections 9, 8 joined together. In this case, the mast head 3 is equipped with two means enabling the mast head to drain rainwater from the exhaust mast 1.

Furthermore, as shown in fig. 3, the mast head 3 has a grille 18 placed over its opening 10. In this case, the grille 18 has two functions. First, the grate prevents any waste larger than the mesh of the grate 18 from entering the exhaust mast. Furthermore, the grate eliminates the risk of backfiring into the mast, which could damage the exhaust mast 1.

According to this embodiment, the first device is a priming system 12 that includes a recovery device 13 and a drain 14. The recovery device 13 is fixed to the side wall 5 of the mast head 3 by means of an assembly element 15. These assembly elements 15 are distributed evenly over the mast head 3 so that the recovery device 12 can be fastened optimally.

In this arrangement, the recovery device 13 is located inside the mast head 3 to recover most of the water entering the mast head due to the main water flow moving in the longitudinal direction at the opening. Furthermore, a recovery device 13 is provided arranged away from the opening 10, leaving a passage for the gas discharge. In order to disturb the discharge of the gas as little as possible, the part of the mast head 3 is larger at the location of the recovery device 13, so that the gas can be discharged despite the presence of the recovery device 13 in the gas path. The recovery device 13 has a rotation axis and an outer diameter at these fixing elements, wherein the assembly elements are equal to the diameter of the opening 10, in order to optimize the recovery of rainwater while disturbing the gas discharge as little as possible.

Fig. 3 shows an embodiment of the air extraction mast 1, which shows the shape of the recovery device, i.e. the funnel in the centre of the mast head 3, wherein the most open part of the funnel is close to the opening 10 and the most closed part is connected to a drainage device 14 for draining water accumulated in the recovery device 13.

In the embodiment shown in fig. 3, the drain 14 is a pipe connecting the recovery device 13 to the outside of the mast head 3, which enables water accumulated in the recovery device 13 to be efficiently drained. Thus, the drain 14 passes through the lower portion 8 of the side wall 5 of the mast to the exterior of the mast head 3. The drain 14 is also inclined at a non-zero angle to the horizontal to allow water to drain naturally from the recovery device 13.

The lower part 8 of the mast head 3 is fixed to the mast body 2 by means of a fixed support 6 as shown in figure 4. Similar to the assembly element 15, the fixed supports 6 are evenly distributed around the periphery of the mast head 3 to ensure a secure and stable fixation between the mast head 3 and the mast body 2. Further, the upper end of the mast body 2 is joined to the inner space of the mast head 3 via the lower end of the mast head 3. The external cross-section of the upper end of the mast body 2 is smaller than the internal cross-section of the lower part of the mast head 3, so that the mast head 3 can be assembled on the side wall 4 of the mast body 2. Thus, the mast head 3 partially covers the mast body 2. Thus, the fastening support 6 forms a gap between the lower end of the lower part 8 of the mast head 3 and the mast body 2, which gap is one of the lengths of the fastening support 6. The gap is designed such that it is carefully considered to form part of the second drainage means.

The mast head 3 further comprises a peripheral connection plate 16 arranged between the outer surface of the upper end of the mast body 2 and the inner surface of the lower part of the mast head 3 to collect residual water flow on the inner surface of the mast head 3, the peripheral connection plate 16 having a through hole 17, the through hole 17 being designed to drain the residual water flow from the mast 1. The lower side wall of the mast head 3 and the crosspiece 16 thus form a gutter 11 around the upper end portion of the mast body 2.

The gutter 11 shown in fig. 3 is then placed between the fastening supports 6, and the gap between the mast head 3 and the mast body 2 is located on the fastening supports 6. The drain drains drain any water that is not recovered by the drainage system 12 and which passes through the inner wall of the mast head 3 through the perforations 17. In this way, the two rain drains act complementarily and prevent rain water from reaching the interior of the mast body 2.

In the embodiment shown in fig. 3, there are eight fastening supports 6, and the eight fastening supports 6 divide the drain 11 into eight parts. Furthermore, the drain 11 is large enough to capture all water that falls between the mast head 3 and the drainage system 12, for example any rain water that falls in a direction other than the longitudinal direction of the mast 1. Such large dimensions have the disadvantage that, if the storage facility is affected, a large gas emission can occur. In this case, the residual gas flow may be discharged by the gutter 11 because the flow is moving at high speed and may travel in the direction of the gutter 11 when striking the priming system 12, as shown in FIG. 8, which simulates the flow of the present invention when a large gas discharge occurs. The residual gas flow then goes to the bottom of the storage facility and poses a hazard to the operator. For this reason, the connecting plate 16 also plays a role in limiting the residual flow rate by allowing only said residual air flow through the perforations 17. This significantly reduces the residual flow, which no longer constitutes a danger to the operator.

FIG. 4 is a schematic illustration of a discharging mast including a priming system according to a second embodiment. In this embodiment, the priming system 12 is located above and away from the opening. Thus, in this case, the system 12 is located outside the mast head 3. The exterior cross-section of the diversion system 12 is larger than the cross-section of the opening 10, thereby enabling the system to perform a function equivalent to the roof of a building. Unlike the first embodiment, the second embodiment enables the main water flow to be split before entering the mast head 3. The priming system 12 may be, for example, a dome plate or a conical element. The priming system 12 may be secured to the mast head using an assembly element 15, which assembly element 15 secures the end of the system 12 to the outer sidewall 5 of the mast head 3.

Fig. 5 shows an assembly element 15 for fastening the priming system 12 to the mast head 3. The assembly element 15 is a flat rod. The end of the assembly element 15 in contact with the mast head is inclined to facilitate its fixing to the mast head, and it consists of two truncated cone shaped parts.

Fig. 6 and 7 show the fastening support 6. In the illustrated embodiment, the fastening support 6 has support holes 7 that allow water received in a first portion of the drain 11 to flow into a second portion of the drain 11, the two portions being separated by the fastening support 6. The support holes 7 thus prevent the portion of a given arrangement without perforations 17 from being filled with water, without having to be able to drain the water accumulated therein.

Fig. 8 shows a peripheral connecting plate 16 with perforations 17. In this embodiment, the webs 16 are circular arcs, forming annular plates when assembled with other webs 16.

Example of dimensions

In an embodiment, mast 1 may have the following dimensions:

Diameter of upper opening 10: 700mm

Diameter of upper and lower junction: 1300mm

Diameter of lower end of lower part: 800mm

Diameter of the mast body 2: 610mm

Diameter of the water recovery device 13: 800mm

Height of the upper part: 200mm

Height of the lower part: 600mm

Height of drain 11: 100mm

Width of the connection plate 16: 105mm

Number of perforations 17: 3

Diameter of the perforation 17: 25 mm.

Fig. 9 is a simulated view of the airflow in the exhaust mast 1. This figure is a simplified view of the exhaust mast 1 showing the main air flow from the mast body 2 and towards the opening 10 in the upper part of the mast head 3 and the residual air flow from the mast body 2 and towards the opening in the lower part of the mast head 3, with the connection plate 16 being located generally below the mast head 3. Thus, the plate 16, while functioning to block this residual airflow, allows the residual airflow to exit through the perforations 17.

referring to FIG. 10, a cross-sectional view of a GN L carrier 70 shows a sealed insulated tank 71 in the shape of a prismatic monolith mounted in the double hull 72 of the vessel the walls of the tank 71 include a primary sealed barrier intended to be in contact with the GN L contained in the tank, a secondary sealed barrier disposed between the primary sealed barrier and the double hull 72 of the vessel, and two insulating barriers disposed between the primary sealed barrier and the secondary sealed barrier and between the secondary sealed barrier and the double hull 72, respectively.

in a manner known per se, a loading/unloading pipe 73 arranged on the upper deck of the vessel may be connected to a marine or harbour terminal by means of suitable connectors for transporting GN L cargo to and from the tanks 71.

Fig. 10 shows an example of an offshore terminal comprising a loading and unloading point 75, a subsea pipeline 76 and an onshore facility 77. The loading and unloading point 75 is a fixed offshore facility that includes a mobile arm 74 and a tower 78, the tower 78 supporting the mobile arm 74. The mobile arm 74 supports a bundle of insulated flexible tubes 79, the insulated flexible tubes 79 being connectable to the loading/unloading duct 73. The orientable mobile arm 74 can accommodate a full-scale lng carrier 70. Connecting lines (not shown) extend within tower 78. The loading and unloading point 75 allows the lng ship 70 to be unloaded to or loaded from an onshore facility 77. The installation has a liquefied gas storage tank 80 and a connecting pipeline 81 which is connected to a loading or unloading point 75 by means of a submarine pipeline 76. The underwater pipelines 76 allow the liquefied gas to be transported over long distances, for example 5km, between the loading or unloading point 75 and the onshore facility 77, so that the liquefied natural gas carrier 70 remains remotely off shore during loading and unloading operations.

To generate the pressure required for the transportation of the liquefied gas, pumps onboard the ship 70 and/or pumps provided with onshore facilities 77 and/or pumps provided with loading and unloading points 75 are used.

Although the invention has been described in connection with a number of specific embodiments, it is evident that the invention is not limited thereto in any way and that it comprises all technical equivalents of the described means and combinations thereof, provided that they fall within the scope of the invention.

Use of the verb "comprise", "have" or "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim.

In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim.