CN112534175B

CN112534175B - Device for supplying and/or discharging a fluid to and/or from a liquefied gas storage tank

Info

Publication number: CN112534175B
Application number: CN201980038502.4A
Authority: CN
Inventors: E.希沃特; B.查彭蒂尔
Original assignee: Gaztransport et Technigaz SA
Current assignee: Gaztransport et Technigaz SA
Priority date: 2018-06-07
Filing date: 2019-05-23
Publication date: 2022-05-10
Anticipated expiration: 2039-05-23
Also published as: WO2019233770A1; FR3082278A1; KR20210013699A; CN112534175A; FR3082278B1

Abstract

Device for supplying and/or discharging a fluid to/from a liquefied gas storage tank (12), in particular of a liquefied gas transport vessel, comprising a pipe (18) having a vertical longitudinal axis (a), an upper end (18a) of which is intended to be connected to means for supplying and/or discharging the fluid, a lower end (18b) of which defines a vertical opening (20), the device being characterized in that it comprises: a substantially horizontal flat bottom wall (22) located opposite the opening, and vertical flat walls (24) for connecting the tube to the bottom wall, at least one of these vertical walls comprising at least one fluid flow aperture (28).

Description

Device for supplying and/or discharging a fluid to and/or from a liquefied gas storage tank

Technical Field

The invention relates in particular to a device for supplying and/or discharging fluid to/from a liquefied gas storage tank, in particular of a liquefied gas carrier.

Background

In order to make it easier to transport gases such as natural gas over long distances, it is common to liquefy the gas (to liquefied natural gas LNG) by cooling it to a low temperature (e.g. -160 ℃ at atmospheric pressure). Then, the liquefied gas is loaded on ships using the gas as fuel, such as LNG ships, refueling ships, and commercial ships.

In order to limit the evaporation of the liquefied gas contained in the tanks of the ship, it is known practice to store it under pressure in the tank so as to move on the evaporation curve of the liquefied gas in question, thus increasing its evaporation temperature. Liquefied gas can thus be stored at higher temperatures, which has the effect of limiting the evaporation of the gas.

However, Natural evaporation of Gas is unavoidable, and this phenomenon is called NBOG, which is an abbreviation for Natural Boil-Off Gas (Natural Boil-Off Gas), as opposed to Forced Boil-Off Gas (Forced Boil-Off Gas) or FBOG. The gas that is normally naturally evaporated in the tanks of the ship is used to supply the ship's energy production plant, which is intended to meet the ship's operations, in particular the ship's propulsion and/or the electricity production of the onboard plant.

Therefore, the liquefied gas storage tank includes liquefied gas and boil-off gas, which is lighter than the liquefied gas, and thus accumulates in the upper portion of the tank. The tank is usually placed under the floor of the ship, which tank usually comprises a liquid dome and a gas dome or a combined dome (liquid and gas), allowing access to the liquid content (liquefied gas) and the gas content (boil-off gas) from the tank.

The liquid dome provides access to a pumping tower that extends vertically in the tank to the bottom thereof. Such a pumping tower comprises means for supplying liquefied gas to the tank, which means comprise a pipe having a vertical longitudinal axis, the upper end of which is connected to a liquefied gas supply source and the lower end of which defines an opening that appears in the vertical direction.

The vertical pipe arrangement makes it possible to inject liquefied gas directly into the bottom of the tank, thereby forming a liquid heel (liquid heel) at the bottom of the tank. The device can be used to charge previously empty tanks with liquefied gas, or to inject liquefied gas into a tank already charged with liquefied gas (or to reinject this same liquefied gas after extracting the gas from the tank in gaseous or liquid form).

The device may also be used to supply air to or remove air from the tank. This is the case, for example, during maintenance operations of the tank, during which the tank is completely emptied and filled with an inert gas intended to be forcibly discharged outside the tank, and to discharge the gas coming from the evaporation of the liquefied gas in the tank outside the tank.

The present invention proposes an improvement to the current art which makes it possible to ensure optimal injection and/or efficient discharge of the fluid, in particular by protecting the components surrounding the device.

Disclosure of Invention

The invention proposes a device for supplying and/or discharging a fluid to/from a liquefied gas storage tank, in particular of a liquefied gas carrier, comprising a pipe having a vertical longitudinal axis, the upper end of which is intended to be connected to means for supplying and/or discharging the fluid, the lower end of which defines a vertical opening, characterized in that it comprises:

-a substantially horizontal flat bottom wall located opposite the opening, and

-vertical flat walls for connecting the tube to the bottom wall, at least one of these vertical walls comprising at least one fluid flow aperture.

The function of the bottom wall is to protect the bottom of the tank from falling objects and jets of fluid which circulate inside the pipe and leave its lower opening in the vertical direction. The bottom wall is positioned practically opposite the opening and prevents the influence of the jet of fluid coming from the object and from the bottom of the tank, which jet is then deflected to mix with the fluid already contained in the tank. The vertical wall provides the connection and mechanical strength of the assembly and includes a fluid passage orifice. The peripheral wall makes it possible to orient the fluid in a desired direction and advantageously towards the remote wall or walls, to improve the fluid-displaced "piston" effect known to the person skilled in the art.

The device according to the invention may comprise one or more of the following features taken separately from each other or in combination with each other:

the tube is substantially cylindrical in shape,

-the bottom wall extends at a distance from the opening,

said bottom wall has a substantially circular shape, preferably non-porous, the diameter of which is preferably greater than the outer diameter of the tube,

-the vertical wall comprises an upper recess for engaging and securing the tube,

-there are two of said vertical walls which substantially intersect at their midportion with said axis.

Said apertures are formed by recesses, for example of inverted U-shape, formed on the lower edges of said vertical walls, which rest on said bottom wall,

-each of said vertical walls comprises at most one or two recesses,

-the cumulative passage section of the orifices is greater than one quarter of the passage section of the openings,

-the cumulative passage section of the orifices is each greater than one quarter of the passage section of the opening,

the bottom wall and at least some of the vertical walls are connected to a peripheral wall extending around the axis,

-said peripheral wall has an overall shape curved around said axis,

-the diameter of the peripheral wall is greater than the outer diameter of the tube,

the peripheral wall extends vertically from the bottom wall to at least one plane perpendicular to the axis and passing through the opening,

the space between the peripheral wall and the tube is closed by a circumferential wall connected to the tube and the peripheral wall,

-the circumferential wall is fixed to the tube and the peripheral wall by welding,

-said circumferential wall is substantially horizontal and is circular-arc-shaped,

the device is entirely metallic.

The invention also relates to a liquefied gas storage tank, in particular for a liquefied gas carrier, comprising at least one device as described above.

The invention also relates to a ship, such as a liquefied gas carrier ship, comprising at least one liquefied gas storage tank in which at least one device as described above is arranged.

Drawings

The invention will be better understood and other details, characteristics and advantages thereof will become more apparent from a reading of the following description, given by way of non-limiting example, with reference to the accompanying drawings. In the drawings:

FIG. 1 is a very schematic perspective view of a liquefied gas storage tank, such as that of a liquefied gas carrier;

FIG. 2 is a very schematic perspective view of the tube of the device according to the invention;

FIG. 3 is a schematic perspective view of an embodiment of a device according to the present invention;

FIG. 4 is a schematic perspective view of another embodiment of a device according to the present invention located at the bottom of a tank;

FIGS. 5, 6 and 7 are schematic views of the device shown in FIG. 4 from the side and top perspective, respectively;

FIG. 8 is a schematic perspective view of another embodiment of a device according to the present invention; and

fig. 9 and 10 are schematic top views of other variant embodiments of the device according to the invention.

Detailed Description

Fig. 1 is a very schematic perspective view of a liquefied gas storage tank 10 of a liquefied gas carrier. The tank 10 shown here has a substantially parallelepiped shape, but in practice it may have a more complex shape.

Such a tank 10 may have larger dimensions, in particular a larger height, for example more than 10 or 20 meters. The tank 10 is generally equipped with a liquid dome 12 which allows access to the liquid content, i.e. liquefied gas, contained in the tank.

The liquid dome 12 provides access to a pumping tower 14 that extends vertically in a tank to the bottom thereof. The pumping tower 14 comprises several items of equipment, including means 16 for supplying fluid to and/or discharging fluid from the tank.

The device 16 comprises a tube 18 having a vertical longitudinal axis a, the length of which is similar to the height of the tank 10, since it is intended to extend to the bottom of the tank, at a short distance therefrom.

Fig. 2 schematically shows the tube 18 of the device 16 according to the invention. The tube 18 has a substantially cylindrical shape, the upper end 18a of which is intended to be connected to means for supplying fluid and/or means for discharging fluid, and the lower end 18b of which is open. The tube shown here is linear but may also contain one or more bends. The outer diameter of tube 18 is, for example, in the range of DN 200 to DN 500. The wall thickness thereof is for example in the range of 2mm to 10 mm. It is preferably made of metal.

The lower end 18b of the tube 18 defines a circular opening 20. The cross section of the tube is constant over its entire height up to the opening 20. The opening 20 extends in a horizontal plane and is thus vertically oriented. As a variant, the section of the tube is not constant over its entire height and may vary, for example, according to the thickness of the tube. The tube may for example have a reinforced portion, in particular an upper portion.

The lower end 18b of the tube 18 is advantageously located at a distance, i.e. at a height, from the bottom of the tank 10 in order to allow fluid to flow between the opening 20 and the bottom of the tank.

The bottom of the tank, as well as other walls of the tank, may be lined with an insulating material and a membrane. In order to protect the membrane from the fluid injected into the tank and the falling objects, the device 16 is equipped with a bottom wall 22, which bottom wall 22 is located below the opening 20, at a distance from and facing the opening 20, and is substantially perpendicular to the vertical axis a of the tube.

In the example shown, the bottom wall 22 has a substantially flat circular shape. It is horizontal and has a diameter denoted D1, which is here larger than the diameter D of the tube 18. The height or distance between the opening 20 and the bottom wall 22 is indicated as H1.

A bottom wall 22 is supported by the tube 18 and is connected to the tube 18 by a vertical connecting wall 24. In the example shown, there are two walls and they substantially intersect in the middle thereof. The wall 24 has here a substantially parallelepiped shape. They are approximately the same size when viewed from above, thus forming either + or x.

The width of wall 24 is greater than the diameter D of tube 18 and is substantially equal to or slightly less than the diameter D1 of bottom wall 22. Their sides with a substantially vertical orientation therefore extend substantially perpendicular to the peripheral edge of the wall 22.

The height H2 of the wall 24 is greater than the height H1. Their lower edges are horizontal and abut the bottom wall 22 and are fixed to the bottom wall 22, for example by welding. Their upper edges are horizontal and include a recess 26 for receiving a portion of the tube 18.

The vertical intersection of the walls 24 is aligned with the axis a of the tube 18 and the vertical recesses 26 are spaced from each other by a distance substantially equal to the diameter D of the tube 18, so that the tube is engaged in the recesses 26 by axial translation from top to bottom. What then remains is to secure the wall 24 to the tube 18, for example by welding.

It will be appreciated that where the

walls

22, 24 are welded to the tube 18, these walls are also made of metal.

The wall 24 cuts the passage section of the opening 20 into four sectors or quarters of the same size, evenly distributed about the axis a.

At least one of the walls 24 includes a fluid flow aperture 28. Each wall 24 may include one or two apertures 26, or even more, each formed by an inverted U-shaped recess. This type of recess is formed from the lower edge of the wall 24 and has a generally vertical orientation.

Advantageously, the cumulative passage section of the orifices 28 is greater than one quarter of the passage section of the tube 18 or of the opening 20.

In a variant not shown, the tube 18 can extend vertically as far as the bottom wall 22 and be fixed thereto.

Fig. 4 to 7 show a further variant embodiment of the device 16, which here comprises an additional wall, which is a peripheral wall 30 extending around the axis a.

The peripheral wall 30 has an overall shape curved about the axis a. The radius of curvature corresponds here to a diameter D2, which diameter D2 is greater than the outer diameter D of the tube and is substantially equal to the diameter D1 of the bottom wall 22. Thus, as can be seen in the drawings, the peripheral wall 30 preferably extends along a portion of the peripheral edge of the bottom wall 22.

The peripheral wall 30 extends vertically from the bottom wall 22 to at least one plane P perpendicular to the axis a and passing through the opening 20. In the example shown, the wall 30 extends even beyond this plane P and covers a portion of the tube 18 (at a radial distance) by defining a circumferential space E around the tube 18.

In the case shown, the wall 30 has an angular extent about the axis a of about 90-100 °, the circumferential space E also having the same angular extent (fig. 7).

The wall 30 may be secured to the bottom wall 22 and the vertical edge of the vertical wall 24 by welding. In the case shown, the circumferential ends of the walls 30 are respectively fixed to the vertical edges closest to the two vertical walls 24.

As best shown in fig. 5, each wall 24 has an aperture 28 in the wall on the side connected to the side edge of the wall 30. It will therefore be appreciated that this wall 30 laterally encloses the cylindrical sector delimited by the wall 24, and that the fluid of the tubes in this sector can be discharged via the orifice 28.

It should also be noted that the height H2 of the wall 30 is therefore equal to the height H2 of the vertical wall 24.

The function of the wall 30 is to protect the items of equipment of the pumping tower or tank that are to be placed in the vicinity of the device 16. If the tube is located on the rear side of the tank, it also allows the fluid to be directed in a desired direction, for example towards the front of the tank. Thus, the wall 30 is angularly positioned about the axis a of the tube 18, so that the fluid injected into the tank is deflected and preferably injected in the opposite direction to the item of equipment to be protected.

Fig. 8 shows an advantageous variant of the invention, in which the aforementioned space E between the tube 18 and the peripheral wall 30 is closed by a circumferential closing wall 32. The wall 32 is preferably substantially horizontal. It is fixed to the tube 18 and the wall 30, for example by welding. On the one hand, it preferably extends radially over the entire radial dimension of the space E and circumferentially over the entire circumferential dimension of this space E and thus of the circumferential wall 30, here with an angular extent of 90-100 °.

The purpose of the circumferential wall 32 is not to allow the fluid to pass upwardly through the space E and therefore not to form an outlet in this region. This promotes drainage of the fluid at the bottom of the tank and thus promotes stratification at the bottom of the tank, that is to say the formation of a layer or stratification of the fluid on the bottom of the tank, for example at a lower temperature.

In the variant of fig. 8, it can also be seen that the size of the orifice 28 is greater than that of the previous embodiment. The passage cross-sections of the recesses forming these orifices may each be greater than one quarter of the passage cross-section of the tube 18 or the opening 20. The recess extends over a height greater than half the height of the vertical wall 24. The increase in the passage section of the orifices makes it possible in particular to reduce the speed of passage of the fluid through these passages.

Fig. 9 and 10 show other variant embodiments of the device, which are, however, shown more schematically.

In the case of fig. 9, the bottom wall 22 is the same as the one described above. The vertical wall 24 has similar dimensions and positions as described above. The difference relates to the peripheral wall 30, which here has an angular extent of approximately 180 °. The wall 30 is fixed to the side edge of the same side wall 24. The side wall 24 comprises two apertures 28, the two apertures 28 being arranged symmetrically with respect to a plane defined by the other wall 24. The further wall 24 comprises a single aperture 28 on the side of the side edge connected to the wall 30. Thus, the wall 30 extends here around two cylindrical sectors defined by the wall 24.

The variant of fig. 10 is a simplification of the variant of fig. 9. The wall 24 connected to the circumferential end of the wall 30 is identical to the wall of the previous variant. The other wall 24 is smaller and forms a T-shape with the first wall (as seen in the drawings). Thus, the further wall 24 extends only between the first wall 24 and the peripheral edge of the bottom wall 22, and is therefore not connected to the wall 30. The further wall 24 may not comprise an aperture 28.

Claims

1. An apparatus (16) for supplying and/or discharging a fluid to/from a liquefied gas storage tank (12), comprising a tube (18) having a vertical longitudinal axis (a), an upper end (18a) of the tube being intended to be connected to means for supplying and/or discharging the fluid, a lower end (18b) of the tube defining an opening (20), the apparatus being characterized in that it comprises:

a substantially horizontal flat bottom wall (22) located opposite the opening, and

vertical flat walls (24) for connecting the tube to the bottom wall, at least one of these vertical flat walls comprising at least one fluid flow aperture (28), the vertical flat walls (24) being two and intersecting.

2. The device (16) of claim 1, wherein the tube (18) is substantially cylindrical.

3. Device (16) according to any one of the preceding claims, wherein the bottom wall (22) extends at a distance from the opening (20).

4. The device (16) of claim 1, wherein the bottom wall (22) has a generally circular shape with a diameter (D1) greater than an outer diameter (D) of the tube (18).

5. The device (16) of claim 1, wherein the vertical planar wall (24) includes an upper notch (26) for engaging and securing the tube (18).

6. The device (16) of claim 1, wherein the vertical planar walls (24) intersect at substantially their middle and the axis (a).

7. Device (16) according to claim 1, wherein the aperture (28) is formed by recesses formed on the lower edges of the vertical flat wall (24), these lower edges resting on the bottom wall (22).

8. Device (16) according to claim 7, wherein each of said vertical flat walls (24) comprises at most one or two recesses.

9. Device (16) according to claim 1, wherein the cumulative passage section of the orifices is greater than one quarter of the passage section of the opening (20).

10. The device (16) according to claim 1, wherein the cumulative passage cross-sections of the orifices are each greater than one quarter of the passage cross-section of the opening (20).

11. The device (16) of claim 1, wherein the bottom wall (22) and the vertical flat wall (24) are connected to a peripheral wall (30) extending about the axis (a).

12. The device (16) of claim 11, wherein the peripheral wall (30) has an overall shape that is curved about the axis (a).

13. The device (16) of claim 12, wherein the diameter (D2) of the peripheral wall (30) is greater than the outer diameter (D) of the tube (18).

14. Device (16) according to claim 13, wherein the peripheral wall (30) extends vertically from the bottom wall (22) to at least one plane (P) perpendicular to the axis (a) and passing through the opening (20).

15. Device (16) according to claim 14, wherein the space (E) between the peripheral wall (30) and the tube (18) is closed by a circumferential wall (32) connected to the tube and to the peripheral wall.

16. The device (16) of claim 15, wherein the circumferential wall (32) is fixed to the tube (18) and the peripheral wall (30) by welding.

17. Device (16) according to claim 15 or 16, wherein the circumferential wall (32) is substantially horizontal and is circular-arc-shaped.

18. The device (16) of claim 1, wherein the device is entirely metallic.

19. Liquefied gas storage tank (12) comprising at least one device (16) according to any of the preceding claims.

20. A ship comprising at least one liquefied gas storage tank (12) in which at least one device (16) according to any one of claims 1 to 18 is housed.