Airtight construction

Abstract

To smoothly discharge gas generated on a side of a region contacting the sea surface in an airtight structure for hermetically sealing the region contacting the sea surface from an upper region in legs of an offshore structure.SOLUTION: An airtight platform 55 of an offshore wind power generator 1 airtightly seals a seawater environmental space 43B in a leg 41, which is in contact with the sea surface W1, from a normal environmental space 43A above. The airtight platform 55 includes a horizontal plate member 61 provided horizontally above the sea surface W1, a gas vent hole 67 provided on a lower surface 61b of a horizontal plate member 61 for passing gas in the seawater environmental space 43B and sending it upward, and a reinforcing portion 63 that has a plurality of beam members 65 joined to the lower surface 61b and reinforces the horizontal plate member 61. The reinforcing portion 63 is provided so as to cross the beam member 65A, and has a gas passage 71 that allows the gas floating and accumulated on the lower surface 61b of the horizontal plate member 61 to pass horizontally along the lower surface 61b.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an airtight structure for an offshore structure. [Background technology]

[0002] An offshore wind turbine described in Patent Document 1 below is known as a conventional offshore structure. This type of wind turbine has a structure in which a wind turbine main body including a nacelle and blades is installed at the upper end of a leg that extends from the seabed into the sky. A management facility for managing the operation of the wind turbine is provided in the hollow part of the cylindrical leg. Meanwhile, below the management facility, seawater has entered the hollow part of the leg up to the same height as the outside seawater level. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5993756 Summary of the Invention [Problem to be solved by the invention]

[0004] In the legs of such wind power generators, in order to suppress salt damage to the management equipment, it is possible to install an airtight structure that airtightly seals the area where seawater has infiltrated from the area of ​​the management equipment. The airtight structure has, for example, a horizontal plate that divides the inside of the legs into upper and lower parts. If gas is generated below the horizontal plate, it is possible that the horizontal plate blocks the rise of the gas and the gas floats and accumulates near the horizontal plate. In this case, a gas vent hole is provided in the horizontal plate, and the gas is discharged above the horizontal plate through the gas vent hole, and finally disposed of by discharging it to the outside of the legs. On the other hand, it is also necessary to ensure the strength of the horizontal plate by a reinforcing structure such as a beam on the lower surface of the horizontal plate. In that case, there is a risk that the reinforcing structure will hinder the smooth movement of gas to the gas vent hole.

[0005] The present invention aims to smoothly discharge gas generated in the area in contact with the seawater surface within the leg of an offshore structure, in an airtight structure that airtightly seals the area in contact with the seawater surface from the area above it. [Means for solving the problem]

[0006] The airtight structure of the present invention is an airtight structure that is provided in the internal space of the cylindrical leg of an offshore structure and airtightly seals the seawater environment space in contact with the seawater level of seawater that has entered the internal space from the normal environment space above, and comprises a horizontal plate that is provided horizontally above the seawater level and divides the internal space into upper and lower parts, a gas vent hole provided on the underside of the horizontal plate for passing gas within the seawater environment space and sending it upward, and a reinforcing section that has a plurality of beams joined to the underside of the horizontal plate and reinforces the horizontal plate, and the reinforcing section is provided across the beams and has a gas passage that allows gas that floats and accumulates on the underside of the horizontal plate to pass horizontally along the underside.

[0007] The beam may have a hollow structure, and the reinforcing part may further include a lid material that airtightly seals the hollow part of the beam from the seawater environment space. The airtight structure of the present invention may be provided above an electric protection equipment having an anticorrosion electrode immersed in seawater in the internal space. The airtight structure of the present invention may further include a ventilation pipe that passes through the normal environment space, connecting the gas vent hole and a gas exhaust port that is provided on the outer surface of the leg above the horizontal plate member and for exhausting gas to the outside of the leg. Effect of the Invention

[0008] According to the present invention, in an airtight structure in which the area in contact with the seawater surface within the leg of an offshore structure is airtightly sealed from the area above it, gas generated in the area in contact with the seawater surface can be smoothly discharged. [Brief description of the drawings]

[0009] [Figure 1] 1 is a front view of a wind power generator to which the airtight structure of the present embodiment is applied. [Diagram 2] FIG. 2 is an enlarged perspective view showing the vicinity of the platform of the wind power generator. [Diagram 3] FIG. 2 is a perspective view showing a part of a leg of the wind power generator, with a part cut away. [Figure 4] 1A is a perspective view showing the airtight platform as viewed from below, and FIG. 1B is a bottom view of the airtight platform. [Diagram 5] 1A is a perspective view of a beam material, FIG. 1B is an enlarged side view showing the vicinity of the gas passage, and FIG. 1C is a perspective view thereof. [Figure 6] FIG. 13A is an enlarged side view showing the vicinity of a gas passage according to a modified example, and FIG. 13B is an exploded perspective view of a beam material in which the gas passage is formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the airtight structure according to the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding elements are given the same reference numerals in the drawings, and duplicated descriptions are omitted as appropriate. In addition, the drawings may be simplified or exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0011] 1 is a front view showing a wind power generator 1 as an example of an offshore structure to which the airtight structure of this embodiment is applied. As shown in the figure, the wind power generator 1 is installed, for example, on the seabed B, and performs offshore wind power generation. However, the wind power generator 1 is not limited to being installed on the ocean, and may be installed, for example, in a lake or a river. The wind power generator 1 includes legs 41 that extend vertically and protrude above the seawater surface from the seabed B, and a generator body 42 attached to the upper end of the legs 41.

[0012] The generator body 42 includes a nacelle 5 and blades 6 attached to the nacelle 5. A generator, a speed increaser, and the like are housed inside the nacelle 5, and for example, a rotor shaft protrudes from the speed increaser to the outside of the nacelle 5. The blades 6 are fixed to the rotor shaft of the nacelle 5. The wind power generator 1 includes, for example, three blades 6. When the blades 6 rotate in response to the wind, this rotation is increased to a certain rotation speed by an amplifier inside the nacelle 5, and this rotational motion is converted into electric power by the generator inside the nacelle 5. For example, the nacelle 5 includes a wind vane and anemometer, and efficient power generation is performed by controlling the orientation of the rotor and the angle of the blades 6 in response to the wind speed and wind direction.

[0013] The leg 41 comprises a foundation 2 which is a monopile driven into the seabed B, a transition piece 3 connected above the foundation 2, and a tower 4 connected further above the transition piece 3. The main bodies of the foundation 2, the transition piece 3, and the tower 4 each have a roughly circular cross section and are arranged coaxially in the vertical direction. Note that the foundation 2 may comprise a tripile-type offshore wind power foundation or a jacket-type offshore wind power foundation instead of a monopile foundation type, and the type of foundation is not particularly limited.

[0014] The upper end of the foundation 2 is located below sea level and has a tapered shape. The lower end of the transition piece 3 has a conical inner surface corresponding to the tapered shape of the upper end of the foundation 2, and the transition piece 3 is installed on the foundation 2 so that the lower end is covered by the upper end of the foundation 2. During construction, the verticality of the transition piece 3 is adjusted on the foundation 2, and grout is filled between the lower end of the transition piece 3 and the upper end of the foundation 2. The foundation 2 and the transition piece 3 are joined (grout jointed) via this grout, and the verticality of the transition piece 3 is ensured, and thus the verticality of the wind turbine 1 is also ensured. The tower 4 is, for example, a vertical column made of concrete or steel, and is bolted to the upper end of the transition piece 3.

[0015] FIG. 2 is an enlarged perspective view of the vicinity of the bolted joint between the transition piece 3 and the tower 4. As shown in FIG. 2, inside the transition piece 3, a multi-layered internal platform 9 for operating and managing the wind power generator 1 is provided. An operator can move between the internal platforms 9 via a ladder or the like. Furthermore, at the upper end of the transition piece 3, an external platform 10 is provided that extends horizontally outward from the outer peripheral surface 3a. Furthermore, at the lower end of the tower 4 that is bolted to the transition piece 3, an entrance / exit 11 for entering and exiting the inside of the tower 4 is provided. An operator who operates and manages the wind power generator 1 moves to the external platform 10 via a ladder from a ship moored at the landing 51 (FIG. 1) near the sea surface. Then, the operator opens the door of the entrance / exit 11 to enter the inside of the tower 4, and can further access the internal platform 9 via an internal ladder or the like. The external platform 10 is used not only as an access route for workers as described above, but also for purposes such as carrying in and out materials and temporarily storing them. For example, a davit crane (not shown) is installed on the external platform 10.

[0016] As shown in FIG. 1, the cylindrical wall of the foundation 2 is provided with a cable hole 45 at a height close to the seabed B for drawing the cable on the seabed B into the internal space 43 of the leg 41, and further provided with a communication hole 47 above the cable hole 45 for allowing seawater to enter and exit the internal space 43. Therefore, seawater enters the internal space 43 of the leg 41 through the cable hole 45 and the communication hole 47, and a seawater level W1 (FIG. 3) exists in the internal space 43 at the same height as the external seawater level W. All of the multiple internal platforms 9 (FIG. 2) as described above are located at a position higher than the above-mentioned seawater level W1. Note that "seawater level W" here means the mean sea level.

[0017] 3 is a perspective view showing a part of the leg 41 with a part cut away. The multiple internal platforms 9 include a lower platform 53 and an airtight platform 55. The lower platform 53 is the multiple internal platform 9 located at the lowest level, and the airtight platform 55 is the internal platform 9 located at the second level from the bottom. Note that the internal platform 9 above the airtight platform 55 includes a cable termination platform on which electrical cables inside the leg 41 are processed, etc., but illustration and detailed description of these are omitted.

[0018] The lower platform 53 is a platform for performing the work of installing the transition piece 3 on the foundation 2 while adjusting the verticality. For example, a plurality of height adjustment devices 53a are arranged in a circumferential direction on the outer peripheral edge of the lower platform 53. The height adjustment devices 53a are fixed to the transition piece 3, and adjust the height of each position of the transition piece 3 by a jack that receives a reaction force from the upper end surface of the foundation 2. After the verticality of the transition piece 3 is adjusted using the plurality of height adjustment devices 53a, grout is filled between the lower end of the transition piece 3 and the upper end of the foundation 2. In the internal space 43, the above-mentioned seawater level W1 is present below the lower platform 53.

[0019] As described above, seawater has entered the internal space 43, and the inner wall surface 2b of the foundation 2 is in contact with seawater below the seawater level W1. Since the foundation 2 is composed of a monopile made of circular steel pipes, it is necessary to prevent corrosion of the inner wall surface 2b of the foundation 2 due to seawater. For this reason, cathodic protection equipment 57 for protecting the inner wall surface 2b is provided on the lower platform 53. The cathodic protection equipment 57 includes a plurality of anticorrosion electrodes 59 suspended from the lower platform 53. As the anticorrosion electrodes 59, for example, platinum-plated electrodes or metal oxide-coated electrodes are used.

[0020] A circular opening 53b for inserting cables is provided at the center of the lower platform 53 in a plan view. Each anticorrosion electrode 59 hangs down vertically from the lower platform 53 through the opening 53b under its own weight. The lower ends of the anticorrosion electrodes 59 reach below the seawater level W1 and are immersed in seawater. The lengths of the multiple anticorrosion electrodes 59 are adjusted so that their lower ends are located at different heights. Furthermore, the cathodic protection equipment 57 has a power supply device 58 that electrically connects the anticorrosion electrodes 59 and the inner wall surface 2b of the foundation 2 in the lower platform 53 and generates a potential difference between them. This forms a so-called external power supply type cathodic protection circuit, and current flows between the anticorrosion electrodes 59 and the inner wall surface 2b of the foundation 2 through seawater, thereby suppressing corrosion of the inner wall surface 2b.

[0021] In this type of cathodic protection equipment 57, chlorine gas and hydrogen gas are generated from the anticorrosion electrode 59 and the inner wall surface 2b. Of these, chlorine gas dissolves in seawater because it is easily dissolved in water, or it remains near the seawater level W1 because it is heavier than air. On the other hand, hydrogen gas rises from the seawater level W1 because it is lighter than air, passes through the lower platform 53, and further rises toward the airtight platform 55. The treatment of this hydrogen gas will be described later.

[0022] In addition, because seawater has entered the internal space 43 as described above, there is a problem that metals and the like are likely to corrode due to salt damage even in the space above the seawater level W1 in the internal space 43. Therefore, in the internal space 43, the space in contact with the seawater level W1 is airtight sealed from the space above the airtight platform 55 by the airtight platform 55. Hereinafter, the space in the internal space 43 below the airtight platform 55 and in contact with the seawater level W1 is referred to as the "seawater environment space 43B," and the space above the airtight platform 55 is referred to as the "normal environment space 43A."

[0023] 4(a) is a perspective view showing the airtight platform 55 as viewed from below, and FIG. 4(b) is a bottom view of the airtight platform 55. As shown in FIG. 3 and FIG. 4, the airtight platform 55 has a circular flat horizontal plate 61 that divides the internal space 43 into a seawater environment space 43B and a normal environment space 43A in two spaces, one above the other. The peripheral portion of the horizontal plate 61 is joined to the inner wall surface 3b of the transition piece 3 without any gaps. In this way, the horizontal plate 61 that crosses the cross section of the internal space 43 airtightly divides the seawater environment space 43B and the normal environment space 43A, thereby suppressing salt damage in the normal environment space 43A.

[0024] As shown in Fig. 3, in the airtight platform 55, cable holes 62a for passing cables and opening / closing hatches 62b for workers to pass through are provided as holes penetrating the horizontal plate material 61. However, these holes are airtight treated and do not impair the airtightness of the horizontal plate material 61. In Fig. 4, the cable holes 62a and opening / closing hatches 62b are omitted to avoid complicating the drawing.

[0025] A reinforcing portion 63 that reinforces the horizontal plate 61 is provided on the lower surface 61b of the horizontal plate 61. The reinforcing portion 63 has a plurality of beams 65 arranged in a grid pattern and welded to the lower surface 61b of the horizontal plate 61. The beams 65 are made of steel material with a U-shaped cross section, and may be manufactured by dividing a square steel pipe into two as shown in FIG. 5(a). The portions of the airtight platform 55 that contact the seawater environment space 43B (the lower surface 61b of the horizontal plate, the surfaces of the beams 65, etc.) may be coated with an anticorrosive coating or the like.

[0026] A gas vent hole 67 is formed in the lower surface 61b of the horizontal plate 61 near the inner wall surface 3b. A gas exhaust port 69 is formed in the vicinity of the gas vent hole 67 at a position above the horizontal plate 61, penetrating the outer wall of the transition piece 3. A ventilation pipe 68 is provided to connect the gas vent hole 67 and the gas exhaust port 69. The ventilation pipe 68 extends in an L-shape through the normal environment space 43A. The seawater environment space 43B is connected at its upper end to the outside of the leg 41 through the ventilation pipe 68. According to this structure, the rise of hydrogen gas generated in the cathodic protection equipment 57 is blocked by the horizontal plate 61 as described above, and the hydrogen gas floats and accumulates under the lower surface 61b, and then the hydrogen gas passes through the gas vent hole 67 and the ventilation pipe 68, and is discharged to the outside of the leg 41 through the gas exhaust port 69.

[0027] Here, there is a risk that the unevenness of the reinforcing portion 63 provided on the lower surface 61b of the horizontal plate member 61 may hinder the smooth discharge of the hydrogen gas. That is, for example, if the beam members 65 of the reinforcing portion 63 were a complete lattice structure, some of the hydrogen gas would accumulate in a rectangular closed area completely surrounded on all four sides by the beam members 65 in a plan view, and this hydrogen gas would not move smoothly to the gas vent hole 67. Therefore, the reinforcing portion 63 in this embodiment is configured so that such a closed area is not formed.

[0028] Specifically, as shown in FIG. 4, the gas passage 71 is formed at a necessary location in the reinforcing portion 63. As shown in FIG. 4(b), in the example of the arrangement of the beams 65 of the reinforcing portion 63, the two central regions 73 can be closed regions completely surrounded by the four beams 65. Therefore, a part of the beam 65A, which is one of the four beams 65, is cut out to form the gas passage 71 that crosses the beam 65A. At the location where the gas passage 71 is provided, the lower surface 61b of the horizontal plate 61 is exposed. With this configuration, the hydrogen gas that floats and accumulates in the region 73 moves horizontally along the lower surface 61b to the adjacent region while passing through the gas passage 71. That is, the gas passage 71 has a function of passing the gas that floats and accumulates on the lower surface 61b of the horizontal plate 61 horizontally along the lower surface 61b.

[0029] FIG. 5(b) is a side view showing an enlarged view of the vicinity of the gas passage 71, and FIG. 5(c) is a perspective view thereof. As shown in the figure, a part of the beam 65A in the longitudinal direction is cut and removed to form the gas passage 71. In this case, the cut end surface of the beam 65A at the gas passage 71 may be inclined with respect to the extending direction of the beam 65. In addition, a lid material 75 is provided on the cut end surface of the beam 65A to airtightly seal the hollow portion of the beam 65A from the seawater environment space 43B. The lid material 75 is, for example, a small rectangular steel plate piece, and is welded to the cut end surface and the lower surface 61b of the beam 65. Due to the presence of such a lid material 75, it is possible to omit anticorrosive coating or the like applied to the inside of the beam 65A.

[0030] Furthermore, as shown in FIG. 4(b), in the reinforcement portion 63, the beam 65 does not reach the surrounding wall surface (the inner wall surface 3b of the transition piece 3). Therefore, each gap between the outer peripheral end of the beam 65 and the inner wall surface 3b also functions as a gas passage 77. This gas passage 77 is also provided so as to cross the beam 65, and has the function of allowing hydrogen gas floating and accumulating on the lower surface 61b of the horizontal plate material 61 to pass horizontally along the lower surface 61b. Note that the cut end surface of the beam 65 in this gas passage 77 is also provided with the above-mentioned cover material 75, so that the hollow portion of the beam 65A is airtightly sealed from the seawater environment space 43B.

[0031] In the reinforcement portion 63, the gas passages 71, 77 as described above are formed at necessary locations, so that, for example, there is no closed region completely surrounded on all four sides by the beam material 65 or the inner wall surface 3b in plan view. That is, the gas passages 71, 77 continuously connect each region on the lower surface 61b side, and hydrogen gas in each region can smoothly move through the gas passages 71, 77 along the lower surface 61b to the gas vent hole 67. As a result, hydrogen gas that gathers near the horizontal plate material 61b of the horizontal plate material 61 is smoothly discharged to the outside of the leg portion 41 through the gas vent hole 67, the inside of the ventilation pipe 68, and the gas exhaust port 69.

[0032] In place of the gas passage 71, a gas passage 79 as shown in FIG. 6(a) may be provided. The gas passage 79 is formed by cutting out the upper edge of the beam 65A that contacts the lower surface 61b of the horizontal plate 61 in a semicircular shape. As shown in FIG. 6(b), semicircular cutouts 81, 81 are provided on the upper edge of the opposing vertical plate of the beam 65A, and a semicylindrical lid 83 is welded to bridge the cutouts 81, 81. The gas passage 79 is provided across the beam 65A, like the gas passage 71, and has the function of passing gas that floats and accumulates on the lower surface 61b of the horizontal plate 61 horizontally along the lower surface 61b. In addition, the presence of the lid 83 hermetically seals the hollow part of the beam 65A from the seawater environment space 43B, and anticorrosive coating or the like applied to the inside of the beam 65A can be omitted.

[0033] The present invention can be embodied in various forms including the above-mentioned embodiment, with various modifications and improvements based on the knowledge of a person skilled in the art. In addition, it is also possible to configure modified examples by utilizing the technical matters described in the above-mentioned embodiment. The configurations of each embodiment and the like may be used in appropriate combination. For example, in the above-mentioned embodiment, the beam material 65 of the reinforcing portion 63 has a U-shaped cross section and a hollow structure, but instead of this, a beam material having a solid structure such as an H-steel may be adopted for the reinforcing portion 63. In addition, the arrangement of the beam material 65 is not limited to that shown in FIG. 4, and may be appropriately changed. Even in this case, it is sufficient that the gas passages 71, 77, and 79 are formed at necessary locations so that there is no closed area completely surrounded on all sides by the beam material 65 or the inner wall surface 3b in a plan view. In addition, in the above-mentioned embodiment, an example in which the airtight structure of the present invention is applied to the airtight platform 55 in the leg 41 of the offshore wind power generator 1 has been described, but the present invention can also be applied to other offshore structures. [Explanation of symbols]

[0034] 1...offshore wind turbine (offshore structure), 41...leg, 43...internal space, 43B...seawater environment space, 43A...normal environment space, 55...airtight platform, 57...electrochemical protection equipment, 59...corrosion protection electrode, 61...horizontal plate material, 61b...underside, 63...reinforcement part, 65,65A...beam material, 67...gas vent hole, 69...gas exhaust port, 68...ventilation pipe, 71,77,79...gas passage, 75,83...cover material, W1...seawater surface.

Claims

1. An airtight structure that is provided in an internal space of a cylindrical leg of an offshore structure and airtightly seals a seawater environment space in contact with the seawater surface of the seawater that has entered the internal space from a normal environment space above, A horizontal plate member that is provided horizontally above the sea level and divides the internal space into upper and lower parts; A gas vent hole provided on the lower surface of the horizontal plate for passing gas in the seawater environment space and sending it upward; a reinforcing portion having a plurality of beam members joined to the lower surface of the horizontal plate member and reinforcing the horizontal plate member; The reinforcing portion is An airtight structure having a gas passageway that is arranged across the beam material and allows gas that floats and accumulates on the underside of the horizontal plate material to pass horizontally along the underside.

2. The airtight structure according to claim 1 , wherein the beam material has a hollow structure, and the reinforcing portion further includes a lid material that airtightly seals the hollow portion of the beam material from the seawater environment space.

3. 3. The airtight structure according to claim 1, which is provided above an electric protection system having an anticorrosion electrode immersed in seawater in the internal space.

4. The airtight structure according to any one of claims 1 to 3, further comprising a ventilation pipe passing through the normal environment space, connecting the gas vent hole and a gas exhaust port provided on the outer surface of the leg above the horizontal plate for exhausting the gas to the outside of the leg.

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