JP2023124020A - Taut mooring floating body, floating structure for mooring preparation, attachment/detachment column, ocean wind power generation facility, and taut mooring method for taut mooring floating body - Google Patents

Abstract

To provide a taut mooring floating body capable of securing stability in a state before taut mooring.SOLUTION: A taut mooring floating body 5 floating on ocean to support a wind power generation facility 3 in a portion on a water surface 101, capable of injecting/ejecting ballast water, being a floating body coupled by sea bottom mooring units 9 which are mooring facilities on the sea bottom and taut mooring ropes 7, and retained in a taut mooring state by tensile force generated in the taut mooring ropes 7 by buoyancy of the floating body includes: one floating column 21 which is columnar extending in the vertical direction with a top end 21c exposed on the water surface 101 with the wind power generation facility 3 installed on the top end 21c; and two submerged columns 23 and 25 coupled to the floating column 21 and including a column support part 45 in a pillar shape with the whole body submerged in the taut mooring state and extending in the vertical direction, with a top end lower than the top end 21c of the floating column 21, and furthermore supporting an attachable/detachable column 43 on the top end which is capable of being attached/detached on the top end, and exposing the top surface of the attachable/detachable column 43 on the water surface 101.SELECTED DRAWING: Figure 1

Description

The present invention relates to a tension mooring floating body, a mooring preparation floating structure, a detachable column, an offshore wind power plant, and a tension mooring method for a tension mooring floating body.

Conventional wind power generation facilities were mainly installed on land, but since there are no obstacles that block the wind like forests or buildings on the sea, turbulence is less likely to occur on land, making it more stable and large. There are sea areas where wind power is generated. Therefore, it is believed that if wind power generation equipment is installed in such a sea area on the ocean and wind power is generated, a larger amount of electric power can be supplied than on land.
When installing wind power generation equipment on the sea, a structure to hold the equipment is required. As such structures, there are two types of structures: the fixed type, in which a structure with a wind turbine is fixed to the seabed, and the floating type, in which a floating structure with a wind turbine is moored to the seabed with mooring ropes. Wind conditions are better than the floor type, and it is generally advantageous in that it can be installed offshore where the installation area is wide.
Among floating structures, there is a catenary mooring structure in which the mooring equipment on the seabed and the floating body are loosely connected with mooring ropes to maintain the position. There is also a tension mooring floating body in which the floating body is forcibly submerged by a mooring cable and the position is maintained by generating tension in the mooring cable by buoyancy (Patent Documents 1 and 2). Tension mooring floats hold the position of the float by the tension of mooring ropes, so compared to catenary mooring structures, it is easier to downsize the float, and it is also advantageous in terms of achieving high stability in a tension mooring state. be.

Japanese Patent Publication No. 2018-526259 Design Registration No. 1519524

On the other hand, tension mooring floating bodies such as those disclosed in Patent Documents 1 and 2 use the tension of the mooring rope to maintain position and ensure stability. In the state before this, there was a problem that the stability of the floating body was worse than that of the catenary mooring type. Moreover, if the floating body is made large in order to ensure stability before being moored under tension, there is a problem that the weight increases and the cost increases.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a lightweight and low-cost tension mooring floating body that can ensure stability before being tension moored.

In order to solve the above problems, the first aspect of the present invention is a seabed mooring section that is a seabed mooring facility that supports a wind power generation facility at a portion above the water surface that floats on the ocean, is capable of pouring and discharging ballast water. A floating body connected by a tension mooring cable, the tension mooring floating body being held in a tension mooring state in which tension is generated in the tension mooring cable by the buoyancy of the floating body, and having a columnar shape extending in the vertical direction, At least one levitation column whose upper end is exposed above the water surface and on which the wind power generation equipment is installed; is lower than the upper end of the floating column, and further comprising a column support that supports a detachable column on the upper end and exposes the upper surface of the removable column above the water surface. Characterized by

A second aspect of the present invention is a floating body structure for mooring preparation, wherein the detachable column is supported by the column support portion of the submerged column of the tension mooring floating body according to the first aspect.

A third aspect of the present invention is a detachable column that is detachably supported by the column support portion of the submerged column of the tension mooring floating body according to the first aspect, and whose upper surface is exposed above the water surface in the supported state. be.

A fourth aspect of the present invention is a tension mooring floating body according to the first aspect, a seabed mooring section that is mooring equipment installed on the seabed, the seabed mooring section and the tension mooring floating body. An offshore wind power generation facility comprising: a tension mooring cable connected in a tension mooring state tensioned by the buoyancy of the floating body; is.

A fifth aspect of the present invention is a method for tension mooring of a tension mooring floating body according to the first aspect, comprising: a towing step of towing the tension mooring floating body before tension mooring to a mooring point over the sea; A detachable column mounting step, which is performed back and forth and attaches the detachable column to the submerged column so that the upper end of the detachable column is exposed above the water surface; a sinking step of sinking the tension mooring floating body before tension mooring in a state where the upper end of the detachable column is exposed above the water surface by injecting ballast water into at least one of the columns; a connecting step of connecting the tension mooring rope to the seabed mooring part in a relaxed state; a tension mooring step of creating a tension mooring state by applying tension to the tension mooring rope; and a detachable column removing step of removing the detachable column from the column support portion of the submerged column after completion of the tension mooring step. characterized by

A sixth aspect of the present invention is a floating body that floats on the ocean, supports a wind power generation facility on the surface of the water, is capable of pouring and discharging ballast water, and is connected to a seabed mooring section, which is a mooring facility on the seabed, by a tension mooring cable. A tension mooring floating body held in a tension mooring state in which tension is generated in the tension mooring rope by the buoyancy of the floating body, the tension mooring floating body being in the shape of a column extending in a vertical direction, the upper end of which is exposed above the water surface, One floating column on which the wind power generation equipment is installed on the exposed upper end, and a column connected to the floating column, the upper end of which is exposed above the water surface, the column extending in the vertical direction, and the upper end of which is higher than the upper end of the floating column. and two low-lying submerged columns configured to adjust tension by adjusting buoyancy with ballast water filling and discharging.

In the configurations of the first to fifth aspects, the vertical height of the upper end of the submerged column is made lower than the upper end of the floating column, thereby lowering the center of gravity of the tension mooring float and ensuring stability. Furthermore, when the tension mooring float is not to be tension moored, a detachable column is mounted on the upper end of the submerged column and the upper end of the detachable column is exposed above the water surface to ensure the stability of the tension mooring float while the submerged column remains submerged. . In the tension mooring state, by removing the detachable column while the submerged column is submerged, the submerged column is submerged, minimizing the influence of external force due to wind and waves, preventing fluctuations in the buoyancy of the tension mooring float due to waves, and submerging. Secure buoyancy in the part where
In addition, by making the vertical height of the upper end of the submerged column lower than the upper end of the floatation column, the submerged column is made shorter than the floatation column, the increase in weight of the tension mooring floating body is minimized, and the manufacturing cost is reduced. curb growth.
Therefore, the tension mooring floating bodies of the first to fifth aspects can ensure stability in the state before being tension moored, and can be lightweight and low cost.

In the configuration described in the sixth aspect, the vertical height of the submerged column, which is not installed, is lower than the floating column where the wind power generation equipment is installed, lowering the center of gravity of the floating body and exposing it above the water surface. To secure the stability of a tension mooring floating body even when it is not moored.
In addition, by making the vertical height of the upper end of the submerged column lower than the upper end of the floatation column, the submerged column is made shorter than the floatation column, the increase in weight of the tension mooring floating body is minimized, and the manufacturing cost is reduced. curb growth.
Therefore, the tension mooring floating body of the sixth aspect can ensure stability in the state before being tension moored, and can be made lightweight and low cost.

ADVANTAGE OF THE INVENTION According to this invention, the stability in the state before tension mooring can be ensured, and the lightweight and low-cost tension mooring floating body can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view showing an offshore wind power generation facility with a tension mooring floating body according to a first embodiment of the present invention; It is a front view which shows the procedure which installs the offshore wind power generation equipment of FIG. 1 on the sea. Figure 2 is a perspective view of the tension mooring floating body of Figure 1; FIG. 2 is a front view showing an example of a column support portion in FIG. 1; FIG. 2 is a perspective view showing an example of a detachable column in FIG. 1; Fig. 4 is a modified example of the arrangement of the braces of the tension mooring floating body of Fig. 3; FIG. 4 is a front view showing an offshore wind power generation facility with a tension mooring floating body according to a second embodiment of the present invention;

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.
First, with reference to FIGS. 1 and 2, a schematic configuration of an offshore wind turbine generator 1 having a tension mooring floating body 5 according to a first embodiment of the present invention will be described.
Here, as the tension mooring floating body 5 of the offshore wind power generation facility 1, the floating body is forcibly submerged by the tension mooring cable 7, and the tension mooring cable 7 is tensioned by the buoyancy to hold the position. . Such a floating body is also called a TLP (Tension Leg Platform).

As shown in FIG. 1 , the offshore wind power generation facility 1 includes a tension mooring floating body 5 , a seabed mooring section 9 , a tension mooring rope 7 , and a wind power generation facility 3 .

The tension mooring floating body 5 shown in FIG. 1 is a floating body that supports the wind power generation equipment 3. The wind power generation equipment 3 is supported by being mounted on a portion above the water surface 101 while floating on the sea. The tension mooring floating body 5 is internally provided with a ballast tank (not shown), into which ballast water can be poured and discharged. Specifically, the ballast water can be injected by introducing surrounding seawater into the ballast tank as ballast water, and the ballast water can be discharged by discharging the injected ballast water to the surroundings.

The reason why the tension mooring floating body 5 is configured to be able to pour and discharge ballast water is to adjust the buoyancy. For example, as shown in FIG. 2(a), the vertical depth from the bottom surface of the tension mooring floating body 5 to the water surface 101 is the depth D1 in the state of free floating without ballast water injection, mooring, and position fixing. Suppose From this state, first, as shown in FIG. 2(b), ballast water is injected into the tension mooring floating body 5 to deepen the draft until the vertical depth reaches a depth D2, which is deeper than the depth D1. It is connected to the seabed mooring part 9 with a tension mooring cable 7 in a called state. In this state, the distance D4 from the seabed mooring section 9 on the seabed 103 to the bottom of the tension mooring floating body 5 is less than the length D5 of the tension mooring cable 7 shown in FIG. 2(c). Then, after the mooring readiness state, the ballast water is discharged. Then, since the buoyancy of the tension mooring floating body 5 becomes larger than the gravity, it tries to rise to a position where the buoyancy and the gravity are balanced. At this time, as shown in FIG. 2(c), the tension mooring floating body 5 is held by the tension mooring cable 7 at a depth D3 corresponding to the vertical height where the buoyancy is greater than the gravity. The depth D3 is deeper than the depth D1 but shallower than the depth D2. Also, at the depth D3, the distance from the seabed 103 to the bottom of the tension mooring floating body 5 is the length D5 of the tension mooring cable 7 . In this state, the tension mooring float 5 is prevented from surfacing by the tension mooring cable 7, so that the tension mooring cable 7 is tensioned by the forced buoyancy, which is a buoyancy force larger than the gravity force. occurs. The tension mooring floating body 5 is held in position by this tension. That is, the tension mooring floating body 5 maintains its position by adjusting the tension of the tension mooring cable 7 by adjusting the buoyancy by filling and discharging ballast water. The state in which the position of the tension mooring floating body 5 is held by the tension of the tension mooring cable 7 is referred to as a tension mooring state in the following description.
In this way, the tension mooring floating body 5 is held in a tension mooring state in which the tension mooring ropes 7 are tensioned by the buoyancy of the floating body, so that the tension mooring ropes 7 are connected to the seabed mooring section 9 which is the mooring facility on the seabed 103 . It is a floating body.

The seabed mooring section 9 is a mooring facility on the seabed 103 that holds the position of the tension mooring floating body 5 via the tension mooring cable 7, and FIG. 1 illustrates piles installed on the seabed 103.
The seabed mooring part 9 has a structure that does not come off from the seabed 103 due to the tension applied from the tension mooring cable 7 when the tension mooring floating body 5 is held in position by forced buoyancy, and has corrosion resistance that does not easily corrode underwater. If available, known mooring equipment may be used. Specifically, gravity anchors, pile anchors, suction anchors, or the like may be used.
Further, the seabed mooring section 9 also includes a connecting section such as a hook or a ring (not shown) for connecting with the tension mooring cable 7 .
In FIG. 1, one offshore wind power generation facility 1 is provided with six submarine moorings 9 . However, the number of seabed moorings 9 may be appropriately set within a range in which the tension mooring ropes 7 apply tension to the seabed moorings 9 to the extent that the tension mooring float 5 does not come off the seabed 103 when the position of the tension mooring floating body 5 is maintained by forced buoyancy. Just do it. For example, nine submarine moorings 9 and nine tension mooring ropes 7 may be provided for one offshore wind power generation facility, and one tension mooring rope 7 may be moored to one submarine mooring 9 .

The tension mooring cable 7 is a mooring cable that connects the tension mooring floating body 5 and the seabed mooring section 9, and the tension mooring floating body 5 is held in a tension mooring state in which the tension mooring cable 7 is tensioned by the buoyancy of the tension mooring floating body 5. to hold the position of the tension mooring floating body 5.
As the tension mooring cable 7, a known mooring cable may be used as long as it has a strength that does not yield or break due to the tensile stress caused by the buoyancy of the tension mooring floating body 5 in a tension mooring state and a corrosion resistance that does not easily corrode in water. Generally, a structure called a Tendon, in which steel pipes are connected in series, is used, but a steel rope, a fiber rope, or a combination thereof may also be used.
In FIG. 1, one offshore wind power generation facility 1 is provided with six tension mooring ropes 7. The necessary number may be set as appropriate.
In FIG. 1, one tension mooring line 7 is moored to one seabed mooring section 9 . However, the number of tension mooring ropes 7 moored to one seabed mooring part 9 should be such that the tension mooring ropes 7 do not come off the seabed 103 when the tension mooring floating body 5 is held in position by forced buoyancy. 7 to the seabed mooring section 9 may be appropriately set.

The wind power generation facility 3 is a power generation facility that converts wind power into electric power, and includes a tower 11, a nacelle 13, a boss 15, and blades 17 in FIG. FIG. 1 illustrates a structure in which wind power is used to rotate blades 17 and bosses 15, and the rotational force of the blades 17 and bosses 15 is used to rotate a rotor of a generator (not shown), thereby converting wind power into electric power.

The tower 11 is a support column that supports the entire wind turbine generator 3, and is a columnar structure extending in the vertical direction. FIG. 1 exemplifies a structure with a cylindrical outer shape, but if it is possible to obtain the strength to support the entire wind power generation equipment 3, it may be constructed in a shape other than a cylindrical shape, such as a conical shape with a downwardly expanding diameter. may have the shape of The lower end of the tower 11 is connected to and supported by the portion of the tension mooring floating body 5 exposed above the water surface 101 .

The nacelle 13 is a hollow structure that incorporates a mechanism (not shown) that converts wind power into electric power. In FIG. 1, it is provided at the upper end of the tower 11 and has a spindle-shaped structure whose axis is parallel to the horizontal direction. . Inside the nacelle 13, there are a power transmission shaft having a horizontal axial direction for transmitting the wind power converted into a rotational force, and a speed increasing device such as a gearbox connected to the power transmission shaft to increase the rotational speed of the power transmission shaft. A machine is provided. Inside the nacelle 13, there are also provided a brake for stopping the power transmission shaft during typhoons and inspections, and a generator for converting rotational force into electric power by connecting a rotor to the power transmission shaft.
Note that the nacelle 13 and the tower 11 are connected by a rotating mechanism that rotates the nacelle 13 about the vertical axis. This is because the axial direction of the power transmission shaft is oriented in the direction of the strongest wind pressure depending on the direction of the wind.

The boss 15 is a cylindrical member provided at the tip of the nacelle 13 in the horizontal direction and supporting the blade 17 . The boss 15 is coaxially connected to the tip of the power transmission shaft, is rotatable about the horizontal direction as the central axis, and is also a member that transmits the rotational force of the blade 17 to the power transmission shaft.
The blades 17 are members that convert wind power into rotational force, and a plurality of blades 17 protrude from the outer circumference of the boss 15 in the radial direction of the boss 15 . Three blades 17 shown in FIG. 1 protrude at equal intervals in the circumferential direction of the boss 15 . Since the blade 17 is a blade inclined at a predetermined inclination angle with respect to the horizontal direction, when it receives wind in the horizontal direction, it moves up, down, left, or right depending on the component of the wind force perpendicular to the horizontal direction. At this time, one end of the blade 17 is connected to the outer circumference of the boss 15, and since the boss 15 is connected to the power transmission shaft and can rotate about the horizontal direction as the central axis, when the blade 17 moves, the boss 15 rotates. . This converts the wind force into rotational force. The wind power converted into rotational force is converted into electric power as the power transmission shaft rotates the rotor of the generator.
The above is the description of the schematic configuration of the offshore wind power generation facility 1 according to the first embodiment.

Next, details of the configuration of the tension mooring floating body 5 according to the first embodiment will be described with reference to FIGS. 1 to 6. FIG.
As shown in FIG. 3, the tension mooring floating body 5 comprises a flotation column 21, submerged columns 23,25, pontoons 29,31,32 and braces 33,35.

The levitation column 21 is a floating body that generates forced buoyancy and also serves as one floating body that supports the wind turbine generator 3. As shown in FIGS. 1 to 3, it has a columnar shape that extends vertically. Floating column 21 has upper end 21c exposed above water surface 101 in both the taut-moored state shown in FIG. 1 and the taut-moored state shown in FIGS. The wind power generation equipment 3 is installed in.
The levitation column 21 shown in FIG. 3 has a cylindrical outer shape. This is to prevent the stress caused by the waves from concentrating on a specific point by allowing the waves to flow along the outer periphery of the cylinder in the opposite direction to the side where the waves hit the levitation column 21 . be. However, if the load received from waves in the sea area where the offshore wind power generation facility 1 is installed is sufficiently smaller than the withstand load of the levitation column 21, the levitation column 21 does not have to have a cylindrical outer shape.

Since the levitation column 21 shown in FIG. 3 has a cylindrical outer shape, the horizontal cross section in the height direction has the same shape and the same size. . In FIG. 3, two tension mooring cables 7 are connected to the bottom of the levitation column 21 by hooks or rings (not shown). can be appropriately set according to the total number of tension mooring ropes 7 required for .

The interior of the floating column 21 may be hollow cylindrical. In this case, the ballast tank 22 is arranged in all or part of the hollow portion. When the ballast tank 22 is not provided in the hollow portion of the floating column 21, a ballast tank (not shown) may be provided in the outer peripheral portion of the floating column 21. FIG.

Since the levitation column 21 supports the wind power generation equipment 3 , the upper end 21 c is exposed above the water surface 101 . If the exposed vertical height is too low, the wind power generation equipment 3 may be submerged by the waves and become unable to generate power. 101 must be exposed. Also, since the portion exposed above the water surface 101 functions as a preliminary buoyant body, the vertical height of the exposed portion is set within a range where necessary preliminary buoyancy can be obtained. Specifically, the vertical height of the portion exposed under tension mooring must be at least higher than the average significant wave height of the sea area where the offshore wind power generation facility 1 is installed, and higher than the maximum significant wave height. is desirable. The same applies to the vertical height of the part exposed in free float or in the mooring preparation state. The average significant wave height is the height of 1/3 of the total number of waves in order from the highest wave height when a predetermined number of wave heights in the sea area where the offshore wind power generation facility 1 is installed are measured at predetermined time intervals. Mean value. The maximum significant wave height means the highest wave height when a predetermined number of wave heights in the sea area where the offshore wind power generation facility 1 is installed are measured at predetermined time intervals. The same applies to the following description. Further, the vertical height of the exposed portion may be the height obtained by multiplying the average significant wave height or the maximum significant wave height by a desired safety factor.

The total length in the vertical direction and the length in the radial direction of the levitation column 21 must be a length that provides the buoyancy necessary to stably support the wind turbine generator 3. 5 becomes large and heavy, increasing the cost and man-hours for installation. Therefore, it is appropriately set within a range in which the necessary buoyancy is obtained and the size is not increased more than necessary.

The levitation column 21 is a floating body on which the wind power generation equipment 3 is installed, but usually only one wind power generation equipment 3 is installed in one offshore wind power generation equipment 1, so one offshore wind power generation equipment 1 is at least It has one floating column 21 . FIG. 1 shows an example with one levitation column 21 .

The submerged columns 23 and 25 are floating bodies that generate forced buoyancy, but unlike the floating column 21 , they are floating bodies that are completely submerged in a tension mooring state and are connected to the floating column 21 . In addition, since the submerged columns 23 and 25 are completely submerged in a tension moored state, unlike the floating column 21, the wind power generation equipment 3 is not installed.

By completely submerging the submerged columns 23, 25 in a tension moored state, waves do not strike the submerged columns 23, 25, so that fluctuations in the buoyancy of the tension moored floating body 5 due to the waves can be reduced. As a result, the load on members that receive forced buoyancy, such as the tension mooring lines 7 and the seabed mooring sections 9, can be reduced, and the number of tension mooring lines 7 and the number of the seabed mooring sections 9 can be reduced. Further, by submerging the entire submerged columns 23 and 25, unlike the case where a part is exposed above the water surface 101, there is no exposed part that is susceptible to wind and wave forces. Therefore, the influence of pressure on the submerged columns 23 and 25 due to wind force and wave force can be reduced, and the structures of the tension mooring floating body 5 and the tension mooring cable 7 can be simplified. Further, by arranging the submerged columns 23, 25 to be entirely submerged in a tension moored state, the vertical height of the upper ends of the submerged columns 23, 25 is lower than the upper end 21c of the floating column 21.例文帳に追加Therefore, the center of gravity of the tension mooring floating body 5 can be lowered, and the stability of the tension mooring floating body 5 can be improved.

The submerged columns 23 and 25 preferably have a cylindrical outer shape like the floating column 21 . The reason for this is that the submerged columns 23 and 25 may expose their upper ends above the water surface 101 in the case of free floating. This is to prevent stress concentration due to However, if the load received by waves in the sea area where the offshore wind power generation facility 1 is towed or installed is sufficiently smaller than the withstand load of the submerged columns 23 and 25, or if the submerged columns 23 and 25 are in a state of free floating, the submerged column may be submerged. If it is not affected by waves, it may not have a cylindrical shape. Therefore, it is preferable that at least one of the floating column 21 and the submerged columns 23, 25 is cylindrical, but neither of them may be cylindrical.

The submerged columns 23 and 25 may have hollow cylindrical interiors similar to the floating column 21 . In this case, a ballast tank (not shown) is arranged in the hollow portion. If no ballast tanks are provided in the hollow portions, ballast tanks (not shown) may be provided on the outer peripheral portions of the submerged columns 23 and 25 .
Since the submerged columns 23 and 25 shown in FIG. 3 have cylindrical outer shapes, their horizontal cross sections in the height direction have the same shape and dimensions. It doesn't have to be. Although two tension mooring cables 7 are connected to each of the submerged columns 23 and 25 in FIG. can be appropriately set according to the strength of hooks, rings, etc., to which are connected, and the total number of tension mooring cables 7 required for tension mooring.

The vertical height of the bottom surfaces of the submerged columns 23 , 25 is preferably the same as the vertical height of the bottom surfaces of the floating columns 21 . In other words, it is preferable that the floating column 21 and the submerged columns 23 and 25 have flush bottom surfaces. This is because the distance between the lower ends of the submerged column 23 and the submerged column 25 is the shortest and the length of the pontoons 29, 31 connecting them can be the shortest.

The total length in the vertical direction and the length in the radial direction of the submerged columns 23 and 25 must be lengths that provide the buoyancy necessary to stably support the wind turbine generator 3. The mooring floating body 5 becomes large and heavy, increasing the cost and man-hours for installation. Therefore, it is appropriately set within a range in which the necessary buoyancy is obtained and the size is not increased more than necessary.
However, since the submerged columns 23 and 25 are submerged under tension mooring, the vertical height of the upper end is lower than the upper end 21c of the floating column 21. Therefore, when the vertical height of the bottom surface of the submerged columns 23 and 25 is the same as the vertical height of the bottom surface of the floating column 21 , the total length of the submerged columns 23 and 25 is shorter than the total length of the floating column 21 .

How much the total length of the submerged columns 23 and 25 is shorter than the total length of the levitation column 21 is set within a range in which necessary buoyancy can be obtained and the size is not increased more than necessary. For example, when the submerged columns 23 and 25 and the floating column 21 have the same vertical height of the bottom surface, the ratio of the total length of the submerged columns 23 and 25 to the total length of the floating column 21 is ⅕ or more and less than 1. If the ratio is less than 1/5, the submerged column 23 will be too small to obtain the necessary buoyancy, and the tension mooring floating body 5 may become unstable against waves. When the ratio is 1 or more, the submerged columns 23 and 25 become longer than the floating column 21, so the submerged columns 23 and 25 cannot be submerged. There is also a possibility that the center of gravity of the tension mooring floating body 5 becomes too high and becomes unstable against waves. A more preferable ratio is 1/2 or more and less than 1.

The vertical height of the submerged columns 23, 25 is preferably such that the upper end is exposed above the water surface 101 in the free floating state. Before tension mooring, the upper end of the tension mooring floating body 5 is exposed above the water surface 101 while the tension mooring floating body 5 is being towed to the mooring point. This is because stability is improved.

The installation positions of the submerged columns 23, 25 are preferably equidistant from each other in the horizontal direction from the flotation column 21, and the horizontal distances between the submerged columns 23, 25 are also preferably equidistant. Specifically, in plan view, it is preferable to form an equilateral triangle with the floating column 21 and submerged columns 23 and 25 as vertices and the pontoons 29, 31 and 32 as sides (see FIG. 3). More specifically, it is preferable to form an equilateral triangle having the centroid of the floating column 21 and the centroid of the submerged columns 23 and 25 as vertices and the neutral axes of the pontoons 29 and 31 as sides. With this arrangement, the lengths of the pontoons 29, 31, 32 are all equal, so that the strength of specific pontoons 29, 31, 32 does not decrease.

A total of two or more submerged columns 23, 25 are provided. This is because if there is one submerged column, the offshore wind power generation facility 1 may overturn if it receives waves perpendicular to the line connecting the floating column 21 and one submerged column. . The preferred number of submerged columns 23, 25 is two as shown in FIG. This is because if there are three or more, the tension mooring floating body 5 becomes large and heavy, and the cost and man-hours for installation increase.

As shown in FIG. 3, the submerged columns 23 , 25 further comprise column supports 45 .
The column support portion 45 is a member that detachably holds the detachable column 43 on the upper ends of the submerged columns 23 and 25 . The detachable column 43 is a floating body that can be attached to and detached from the submerged columns 23 and 25, and has a cylindrical outer shape similar to the submerged columns 23 and 25 in FIG. The column support part 45 exposes the upper surface of the detachable column 43 to the water surface 101 by supporting the detachable column 43 at its upper end.

The reason why the submerged columns 23 and 25 are provided with the column support portions 45 is as follows.
The tension mooring floating body 5 according to the first embodiment submerges the submerged columns 23 and 25 entirely, thereby suppressing fluctuations in buoyancy due to waves and reducing the external force applied to the submerged columns 23 and 25 for tension mooring. The structure of the floating body 5 is simplified.

On the other hand, if the submerged columns 23, 25 are entirely submerged, the stability and stability of the submerged columns 23, 25 are lower than when the submerged columns 23, 25 are exposed above the water surface 101 in the non-tension mooring state. For example, while the tension mooring floating body 5 is being towed to a planned installation position on the sea, or in a mooring preparation state in which forced buoyancy is to be generated by pouring and discharging ballast water as shown in FIG. Stability is low and stability is low in the state before being installed.

2(a) and 2(b), the detachable column 43 is supported by the column support portion 45 at the upper ends of the submerged columns 23, 25 and is exposed above the water surface 101 before the tension mooring state. . As a result, the stability of the tension mooring floating body 5 can be enhanced by the amount of the detachable column 43 exposed above the water surface 101 . Therefore, even when the submerged columns 23 and 25 are entirely submerged in water and before tension mooring, the stability of the tension mooring floating body 5 can be enhanced, and stability can be ensured. Especially in the mooring preparation state shown in FIG. 2(b), unlike the towing state shown in FIG. is in a state where sufficient stability cannot be obtained. Therefore, the detachable column 43 is highly effective in improving stability.

In addition, as shown in FIG. 2(c), after the tension mooring state is reached, the tension mooring floating body 5 is tension moored so that the position of the mooring point is maintained and stabilized. There is no need to ensure gender. Then, the detachable column 43 is removed from the submerged columns 23 and 25 .

In this way, the attachment/detachment column 43 is detachably provided on the upper ends of the submerged columns 23 and 25 before the tension mooring state, and is removed after the tension mooring state, so that the column 43 is driven into the attachment and detachment column 43 in the tension mooring state. There is no buoyancy fluctuation or pressure caused by waves. Therefore, even if the detachable column 43 is detachably provided, the number of the tension mooring ropes 7 and the number of the seabed mooring sections 9 may be increased, or the structure of the tension mooring floating body 5 may be increased in consideration of buoyancy fluctuations and pressure due to waves. No need to reinforce.

In addition, by submerging the entire submerged column 23 in the water so that the upper end 21c of the floating column 21 is positioned above the water surface 101, the vertical height of the upper ends of the submerged columns 23 and 25 is inevitably the height of the floating column 21. It is lower than the vertical height of the upper end 21c. Therefore, compared to the case where the vertical height of the upper ends of the submerged columns 23 and 25 is set to the same level as the height of the upper end 21c of the floating column 21, the center of gravity of the tension mooring floating body 5 is lowered, which is more advantageous in terms of stability. .

As shown in FIGS. 2(a) and 2(b), a detachable column 43 is detachably attached to the upper ends of the submerged columns 23 and 25, and the tension mooring floating body 5 and the detachable column 43 are combined before being tension moored. This structure is also called a mooring preparatory floating structure.

The structure of the column support part 45 is such that the detachable column 43 can be detachably held at the upper end of the submerged columns 23, 25, and the tension mooring floating body 5 can be moved up and down due to waves received during towing and ballast water pouring and discharging in preparation for mooring. The detachable column 43 should not be detached from the submerged columns 23 and 25 .
Also, the column support portion 45 may have any structure as long as it rigidly connects the submerged columns 23 and 25 and the detachable column 43 . The term "rigidly connected" as used herein means a structure in which the submerged columns 23, 25 and the detachable column 43 move integrally while the detachable column 43 is held by the submerged columns 23, 25. As shown in FIG. As a specific structure of the column support portion 45, the following structure can be exemplified.

The first example is a structure using bolt fastening as shown in FIG. 4(a).
The column support portion 45 shown in FIG. 4A includes a support portion-side flange 51 and bolts 55 .
The supporting portion-side flange 51 is a member protruding radially from the side surface of the upper end of the submerged columns 23 and 25, and has a through hole 53 penetrating vertically. 4A is a ring-shaped member that covers the entire circumference of the side surfaces of the submerged columns 23 and 25, only the portion where the through hole 53 is provided may protrude.
The bolt 55 is a threaded rod inserted through the through hole 53 of the support side flange 51. Here, a bolt having a bolt head such as a hexagonal bolt is exemplified, but a stud bolt may be used. In the following description, a hexagonal bolt is used as an example.

When the column support portion 45 has the support portion side flange 51 and the bolt 55 , the removable column 43 has the removable column side flange 57 . The detachable column-side flange 57 is a ring-shaped member radially protruding from the side surface of the lower end of the detachable column 43 and has a bolt insertion hole 59 penetrating in the vertical direction. The detachable column-side flange 57 may protrude only at the portion where the bolt insertion hole 59 is provided, similarly to the support portion-side flange 51 . Further, the position where the bolt insertion hole 59 is provided is the position where the through hole 53 overlaps with the upper surface of the submerged columns 23 and 25 and the lower surface of the detachable column 43 on the plane. The diameter of the bolt insertion hole 59 is such that the bolt 55 can be inserted therethrough, and specifically, it is approximately the same as the diameter of the through hole 53 .
In this configuration, first, the bolts 55 are inserted through the through holes 53 of the support portion side flange 51 and the bolt insertion holes 59 of the detachable column side flange 57 . Further, the column support portion 45 supports the detachable column 43 by screwing and tightening the nut 61 from the tip of the bolt 55 where the bolt head is not provided.

Thus, the column support portion 45 shown in FIG. 4A has a structure for supporting the detachable column 43 by bolting.
In this structure, a known mechanism combining a flange, a bolt and a nut can be used, so the design is easy.

A second example is a structure using a hook 73 as shown in FIG. 4(b).
The column support portion 45 shown in FIG. 4B includes a pair of engaging portions 71 that are protrusions radially protruding from the side surfaces near the upper ends of the submerged columns 23 and 25 or radially recessed recesses. FIG. 4(b) illustrates, as an example of the engaging portion 71, a projection protruding radially from the side surfaces of the submerged columns 23 and 25 in the vicinity of the upper ends. A pair of engaging portions 71 are opposed to each other.

On the other hand, when the column support portion 45 has the engaging portion 71, the attachment/detachment column 43 has a pair of hooks 73 rotating about the horizontal axis on its side surface. More specifically, the attachment/detachment column 43 has a pair of hook support portions 75 projecting radially from the side surface near the lower end. A pair of hook support portions 75 hold a horizontal rotating shaft 77 that is parallel to the tangential direction of the outer periphery of the attachment/detachment column 43 at the location where the hook support portions 75 are provided. The pair of hooks 73 are J-shaped hooks that engage with the pair of engaging portions 71 , the upper ends of which are supported by a rotary shaft 77 , and the tips 74 of which are directed toward the attachment/detachment column 43 with the rotary shaft 77 as the center. It rotates in one direction E1 and away in the direction E2. The position on the plane where the pair of hooks 73 are provided is the position where the position on the plane overlaps with the engaging portion 71 when the upper surfaces of the submerged columns 23 and 25 and the lower surface of the detachable column 43 are butted against each other. . The tips 74 of the pair of hooks 73 face each other.

In this configuration, first, the pair of hooks 73 are rotated in the direction E2 to move the tips 74 away from the detachable column 43, and then the top surfaces of the submerged columns 23 and 25 and the bottom surface of the detachable column 43 are brought into contact. Next, the pair of hooks 73 are rotated in the direction of E1 so that the insides of the tips 74 are brought into contact with the lower surfaces of the pair of engaging portions 71, and the pair of hooks 73 are rotated so as to sandwich the submerged columns 23 and 25. The detachable column 43 is supported by being engaged with the pair of engaging portions 71 . If the engaging portion 71 is a concave portion, the tip 74 is inserted into the concave portion of the engaging portion 71 for engagement.

In FIG. 4B, the engaging portions 71 are provided on the submerged columns 23 and 25, and the hook 73 is provided on the detachable column 43. It may be provided in the columns 23,25. In other words, the column support portion 45 may be provided with either the engaging portion 71 provided on the side surface of the submerged columns 23, 25 or the hook 73 provided on the side surface of the submerged columns 23, 25 and rotating about the horizontal axis. , the detachable column 43 may be provided with the other of the engaging portion 71 and the hook 73 . Moreover, there may be two or more pairs of the engaging portion 71 and the hook 73 .

In this manner, the column support portion 45 may have a structure in which the hook 73 is engaged with the engaging portion 71 and fixed.
With this configuration, the attachment/detachment column 43 can be attached/detached only by rotating the hook 73, so workability is excellent.

A third example is a structure using a stud 83 with a spherical tip and a socket 85 as shown in FIG. 4(c).
The column support portion 45 shown in FIG. 4(c) is provided with a pair of studs 83 projecting upward from the submerged columns 23, 25 and having spherical tips. More specifically, the column support portion 45 includes a pair of stud support portions 81 projecting radially from the side surfaces of the upper ends of the submerged columns 23 and 25. 83 is projected. A pair of stud support portions 81 and a pair of studs 83 face each other.

On the other hand, if the column support portion 45 has a pair of studs 83, the detachable column 43 has a pair of sockets 85 that hold the spherical portions of the studs 83 so as to wrap around them. Specifically, the socket 85 is a member projecting radially from the side surface of the lower end of the detachable column 43 , and has an inner circumferential recess corresponding to the spherical portion of the stud 83 on the lower surface. The position on the plane where the socket 85 is provided is the position where the position on the plane overlaps the stud 83 when the upper surfaces of the submerged columns 23 and 25 and the lower surface of the detachable column 43 are butted against each other.
In this structure, the column support portion 45 is structured to support the detachable column 43 by inserting the spherical portion of the stud 83 into the socket 85 .

As a structure for fixing the spherical portion of the stud 83 to the socket 85, the following structure can be exemplified.
Specifically, on the surface of the spherical portion of the stud 83, a pin 84 is provided that can be pulled in and out in a direction perpendicular to the insertion direction of the stud 83 toward the socket 85, and the pin 84 is housed in the surface of the concave portion of the socket 85. A structure in which holes 86 are provided can be exemplified. In this structure, the stud 83 is fixed to the socket 85 by inserting the stud 83 into the socket 85 and then inserting the pin 84 into the hole 86 .

In FIG. 4C, the studs 83 are provided on the submerged columns 23 and 25 and the sockets 85 are provided on the removable columns 43. may be set to In other words, the column support portion 45 may be provided with either the stud 83 or the socket 85 , and the detachable column 43 may be provided with the other of the stud 83 or the socket 85 . Two or more pairs of studs 83 and sockets 85 may be provided. You can set them one by one.

In this manner, the column support portion 45 may have a structure in which the spherical portion of the stud 83 is inserted into the socket 85 and fixed.
In this structure, even if an external force is applied to the column support portion 45 while it is fixed, the opposing surfaces of the spherical socket 85 and the stud 83 receive the load, so the stress due to the load is less likely to concentrate in one place.

The specific structure of the detachable column 43 can be appropriately set as long as the detachable column 43 is supported by the column support portion 45 and is not submerged in water and the upper end is exposed above the water surface 101 . A specific vertical height of the detachable column 43 is appropriately set according to the sea area where the detachable column 43 is installed, the size of the cargo compartment of the work boat for installation of the detachable column 43, the maximum load capacity, and the upper limit of the lifting load. However, when the detachable column 43 is supported by the column support portion 45 and in the mooring preparation state, the vertical height of the portion exposed above the water surface 101 is at least should be higher than and preferably higher than the maximum significant wave height. This is because the possibility that the entire detachable column 43 is submerged by waves is extremely low. Furthermore, the vertical height of the portion exposed above the water surface 101 may be a value obtained by multiplying the average significant wave height or the maximum significant wave height by a desired safety factor.
Specific examples of the structure of the attachment/detachment column 43 include the following three.

First, there is a structure having a columnar outer shape whose axial direction is oriented vertically, such as the attachment/detachment column 43 shown in FIGS. 1 to 4 and 5(a). The columnar shape can prevent stress concentration when waves are driven into the floating column 21, similarly to the case where the floating column 21 is columnar. When the submerged columns 23 and 25 are cylindrical, it is preferable that the diameter of the column is about the same as the diameter of the submerged columns 23 and 25 because the column support portion 45 and the detachable column 43 are unlikely to interfere with each other.

When the detachable column 43 has a cylindrical outer shape, the interior of the detachable column 43 has a watertight structure to prevent water from entering. It is preferable that this watertight structure has a ballast tank (not shown) so that the buoyancy of the detachable column 43 can be adjusted by pouring and draining ballast water. The reason for this is that when the detachable column 43 is detached from the column support portion 45, it is preferable to remove the detachable column 43 after neutral buoyancy. Neutral buoyancy indicates a state in which buoyancy and gravity are in balance with the same value. When the detachable column 43 is removed from the column support portion 45, if the buoyancy is not neutral, for example, if the buoyancy is greater, the detachable column 43 will suddenly rise due to the buoyancy at the moment of removal, and the tension mooring floating body 5 and the mooring work will be suspended. It can hit and damage the equipment. In addition, when the gravity is greater, the detachable column 43 sinks due to gravity the moment it is removed, so the load required to move the detached detachable column 43 is greater than in the case of neutral buoyancy. Therefore, it is preferable that the detachable column 43 has a structure in which the buoyancy can be adjusted by pouring and discharging ballast water.

In this structure, the detachable column 43 has a cylindrical outer shape and is watertight, so that the column support portion 45 supports the detachable column 43 and exposes the upper end of the detachable column 43 above the water surface 101 . To secure the stability of a tension mooring floating body 5 with a column 43 mounted thereon.
In this configuration, since the detachable column 43 has a columnar watertight structure, even if a wave hits the detachable column 43, there is a low possibility that the top end of the detachable column 43 will be flooded.

Next, there is a structure including a bulwark 65, like the detachable column 43a shown in FIG. 5(b). Specifically, the attachment/detachment column 43a shown in FIG. The floor portion 63 is a disk-shaped watertight structure with an axial direction oriented vertically, and is mounted on the upper surface of the submerged column 23 when the detachable column 43 a is supported by the column support portion 45 . The bulwark 65 is a cylindrical wall erected on the upper surface of the floor 63 along the outer circumference of the floor 63, and the lower surface, which is the connecting portion with the floor 63, and the outer circumference of the wall are watertight. . By forming the bulwark 65 into a cylindrical shape, similarly to the case of forming the levitation column 21 into a cylindrical shape, it is possible to prevent stress concentration when waves are driven into the bulwark 65 . The vertical height of the bulwark 65 is the same as the vertical height of the detachable column 43 . Specifically, the vertical height of the portion exposed above the water surface 101 in the state of being supported by the column support portion 45 and in the mooring preparation state is at least higher than the average significant wave height of the sea area where the offshore wind power generation equipment 1 is installed. It should be high, preferably higher than the maximum significant wave height. Alternatively, a value obtained by multiplying the average significant wave height or the maximum significant wave height by a desired safety factor may be used.
In this structure, the column support portion 45 supports the detachable column 43a and exposes the upper end of the bulwark 65 above the water surface 101 to ensure the stability of the tension mooring floating body 5 with the detachable column 43a mounted thereon.
In this configuration, since the upper end of the detachable column 43a is open, the weight of the detachable column 43a can be easily reduced.

Furthermore, as in the detachable column 43b shown in FIG. 5(c), there is a structure in which the floor portion 63 is formed into a columnar shape and a bulwark 65 is erected on the floor portion 63. As shown in FIG. Specifically, the attachment/detachment column 43a shown in FIG. The floor portion 63 is a columnar watertight structure whose axial direction is oriented vertically, and is mounted on the upper surface of the submerged column 23 when the detachable column 43 b is supported by the column support portion 45 . The bulwark 65 is a cylindrical wall erected on the upper surface of the floor 63 along the outer circumference of the floor 63, and the lower surface, which is the connecting portion with the floor 63, and the outer circumference of the wall are watertight. . The structure shown in FIG. 5(c) can be said to be a structure in which a bulwark 65 is provided on the upper surface of the columnar detachable column 43 shown in FIG. 5(a). It can also be said to be a columnar structure with an increased vertical height. By making the floor portion 63 cylindrical and the bulwark 65 cylindrical, it is possible to prevent stress concentration when waves are driven into the buoyant column 21 .

The upper end of the floor portion 63 is preferably positioned higher than the waterline in the state where the detachable column 43a is supported by the column support portion 45 and in the mooring preparation state. This is because water can be easily drained when waves hit the detachable column 43a and the area surrounded by the bulwarks 65 is flooded. In addition, with the detachable column 43a supported by the column support portion 45 and in the mooring preparation state, the vertical height from the draft line to the upper end of the floor portion 63 is the average significance of the sea area where the offshore wind power generation equipment 1 is installed. It should be higher than the wave height and preferably higher than the maximum significant wave height. Furthermore, it may be a height obtained by multiplying the average significant wave height or the maximum significant wave height by a desired safety factor. This is because the possibility that the portion surrounded by the bulwarks 65 of the detachable column 43a will be flooded with water when waves hit the portion surrounded by the bulwarks 65 is extremely low.

In this structure, the floor portion 63 of the detachable column 43b has a watertight structure having a cylindrical outer shape, so that the column support portion 45 supports the columnar detachable column 43b so that the upper end of the detachable column 43 is above the water surface 101. expose. Thereby, the stability of the tension mooring floating body 5 in the state where the detachable column 43b is mounted is ensured. Furthermore, by erecting the bulwark 65 on the floor 63, when the equipment used for tension mooring of the tension mooring floating body 5 is installed on the floor 63, the installation can be prevented from the waves hitting the detachable column 43b. A bulwark 65 can protect the equipment that has been exposed.

Since the attachment/detachment columns 43, 43a, and 43b shown in FIG. 5 have a columnar or cylindrical outer shape, the length from the axis to the outer edge in the horizontal section is constant. However, the horizontal cross section of the detachable columns 43, 43a, 43b may have a horizontal cross section in which the length from the axis to the outer edge is not constant, such as a polygon.

Pontoons 29, 31 and 32 shown in FIG. 3 are members for connecting the floating column 21 and the submerged columns 23 and 25, which constitute the tension mooring floating body 5, and the submerged columns 23 and 25 which are submerged columns. Specifically, the pontoons 29 , 31 , 32 are members that connect the lower ends of the floating bodies that constitute the tension mooring floating body 5 . In FIG. 3, a pontoon 29 connects the lower end of the flotation column 21 and the lower end of the submerged column 25 . A pontoon 31 connects the lower end of the floating column 21 and the lower end of the submerged column 23 . A pontoon 32 connects the lower end of the submerged column 23 and the lower end of the submerged column 25 .

Since the pontoons 29, 31, 32 are members connecting the lower ends of the floating bodies constituting the tension mooring floating body 5, when the bottom surfaces of the floating column 21 and the submerged columns 23, 25 are flush with each other as shown in FIG. It becomes a member extending to
In addition, the submerged columns 23, 25 are members that are entirely submerged, and the pontoons 29, 31, 32 are connected to the lower ends of the submerged columns 23, 25, so that the pontoons 29, 31, 32 are also entirely submerged members. .

The pontoons 29, 31, 32 have the strength necessary to maintain the connected state of the floating column 21 and the submerged columns 23, 25, and the submerged column 23 and the submerged columns 25, and also have corrosion resistance so that they do not easily corrode underwater. The structure and materials can be selected as appropriate. However, since the pontoons 29, 31, and 32 are members that are entirely submerged in water and are not easily affected by waves, their outer shapes do not necessarily have to be cylindrical in structure so that the stress caused by waves does not concentrate on specific points. The pontoons 29, 31, 32 shown in FIG. 3 exemplify a structure having a prismatic outer shape. Also, if the horizontal lengths of the pontoons 29, 31, 32 are too long, they may buckle due to an external force such as an ocean current. On the other hand, if the horizontal lengths of the pontoons 29, 31, 32 are too short, the distance between the floating column 21 and the submerged columns 23, 25 will be too short and they will become like one column, which will reduce external forces such as waves. There is a possibility that the offshore wind power generation equipment 1 will overturn when it receives it. Therefore, the horizontal lengths of the pontoons 29, 31, and 32 are appropriately set within a range in which the pontoons 29, 31, and 32 do not buckle and do not overturn when the offshore wind power generation facility 1 receives an external force such as waves. The greater the area of the axial cross section of the pontoons 29, 31, 32, the greater the resistance to buckling. , some parts cannot be connected. Therefore, the area of the axial cross section of the pontoons 29, 31, 32 is within the range that can prevent buckling and is within the range of the connecting portions of the floating column 21 and the submerged columns 23, 25 with the pontoons 29, 31, 32. set.

The braces 33, 35 are reinforcing members that are provided as necessary when the pontoons 29, 31, 32 alone do not have enough strength to connect the floating bodies constituting the tension mooring floating body 5. Specifically, the braces 33 and 35 are members that protrude obliquely downward from the upper end 21c of the floating column 21 and connect the submerged columns 23 and 25 or the pontoons 29, 31 and 32 to each other.

3, a brace 33 connects the upper end 21c of the floating column 21 and the upper end of the submerged column 23. In FIG. A brace 35 connects the upper end 21 c of the floating column 21 and the upper end of the submerged column 25 . In this construction, the tension mooring floating body 5 has a triangular pyramidal profile with the buoyant column 21, the braces 33, 35 and the pontoons 29, 31, 32 as sides.

By providing the brace 33 in this manner, the floating column 21 and the submerged columns 23, 25 are connected via not only the pontoons 29, 31 but also the braces 33, 35.
Therefore, compared to the case where the floating column 21 and the submerged columns 23, 25 are connected only by the pontoons 29, 31, 32, it is easier to secure the strength necessary to maintain the connected state.

Alternatively, in a structure in which two braces 33, 35 connect the upper end 21c of the flotation column 21 and the two submerged columns 23, 25, respectively, the tension mooring floating body 5 is connected to the flotation column 21, the braces 33, 35, and the pontoons 29, 31, It becomes a triangular pyramid-shaped truss structure with 32 as a side. Also, in this structure, the submerged columns 23, 25 are the vertices of a triangular pyramid.
In this configuration, the strength of the floating body can be improved as compared with the case where the floating column 21 and the submerged columns 23 and 25 are simply connected with the braces 33 and 35 at the shortest distance.

If the braces 33, 35 have the necessary strength to reinforce the connection between the floating column 21 and the submerged columns 23, 25 by the pontoons 29, 31, 32 and have corrosion resistance so that they do not easily corrode in water, The structure and material can be selected as appropriate. However, braces 33, 35 are preferably cylindrical. The reason is as follows.
Since the braces 33 and 35 shown in FIG. 3 are structured to protrude obliquely downward from the upper end 21c of the levitation column 21, there are portions exposed above the water surface 101. As shown in FIG. Therefore, waves may hit the braces 33 and 35 .
On the other hand, when the braces 33, 35 are cylindrical, when waves are driven into the braces 33, 35, the waves flow along the outer periphery of the cylinders to the side opposite to the driven side.
Therefore, compared with the case where the braces 33 and 35 are square tubes, the stress caused by the waves driven into the braces is less likely to concentrate at specific locations, and the strength of the braces 33 and 35 can be improved.

The braces 33 and 35 shown in FIG. 3 are structures that connect the upper end 21c of the levitation column 21 and the two submerged columns 23 and 25, respectively, and improve strength by forming a triangular pyramidal truss structure.
On the other hand, it is sufficient that the braces 33, 35 can reinforce the connection between the floating column 21 and the submerged columns 23, 25 by the pontoons 29, 31, 32. Therefore, it is not always necessary to have a structure in which the floating column 21 and the submerged columns 23 and 25 are directly connected as shown in FIG.

For example, as shown in FIG. 6( a ), a buckling prevention brace 91 connects the middle portion between both ends of the brace 33 and the pontoon 31 , and the middle portion between both ends of the brace 35 connects the pontoon 29 . Buckling braces 93 may also be provided. If there is a possibility that the braces 33 and 35 may buckle due to the stress caused by the swaying of the tension mooring floating body 5 or the ocean current, the buckling prevention braces 91 and 93 connect the parts that may buckle and the pontoons 31 and 29. It is a member that prevents bending.
By providing the buckling prevention braces 91 and 93 in this way, it is possible to prevent the braces 33 and 35 from buckling due to an external force.

Alternatively, as shown in FIG. 6(b), braces 33 and 35 may connect the upper end 21c of the levitation column 21 and the pontoons 31 and 29 in the middle between both ends. This structure is advantageous when the diameter of the submerged columns 23, 25 is too small to install the connecting portion for connecting the brace 33 on the submerged columns 23, 25 side.

Furthermore, as shown in FIG. 6(c), a single brace 95 may be used to connect the upper end 21c of the levitation column 21 and the middle portion between both ends of the pontoon 32. As shown in FIG. This structure is used when sufficient strength can be secured for reinforcement with a single brace 95, or when the diameter of the submerged columns 23, 25 is too small to install the connecting portion connecting the braces 33 on the submerged columns 23, 25 side. It is advantageous to Moreover, it is advantageous when the diameter of the levitation column 21 is too small and it is difficult to install a connecting portion for connecting the plurality of braces 33 and 35 to the levitation column 21 .

It should be noted that the braces 33, 35 do not necessarily need to be provided if the pontoons 29, 31, 32 alone have sufficient strength to connect the floating bodies constituting the tension mooring floating body 5.
The above is the detailed description of the configuration of the tension mooring floating body 5 according to the first embodiment.

Next, a procedure for installing the offshore wind turbine generator 1 according to the first embodiment on the sea will be briefly described with reference to FIG. Since the tension mooring floating body 5 needs to be tension moored in order to install the offshore wind power generation facility 1 on the sea, the following procedure is also an explanation of the tension mooring method of the tension mooring floating body 5 .
First, the wind power generation equipment 3 is installed on the tension mooring floating body 5 assembled at the construction site before the tension mooring, and as shown in FIG. It is towed on the sea by a crane boat or a tug boat to the planned installation position. This process is also called a towing process.

Next, as shown in FIG. 2( a ), the detachable column 43 is attached to the submerged columns 23 and 25 so that the upper end is exposed above the water surface 101 . This process is also called a detachable column mounting process.
The detachable column mounting process may be performed before or after the towing process. Therefore, as shown in FIG. 2(a), the towing process may be performed after attaching the detachable column 43 to the submerged columns 23 and 25, or the tension mooring floating body 5 before tension mooring may arrive at the mooring point. The detachable column 43 may be attached to the submerged columns 23 and 25 after the towing process is completed. However, when the detachable column mounting process is carried out after the towing process, the upper ends of the submerged columns 23 and 25 are exposed above the water surface 101 when the tension mooring floating body 5 before tension mooring is in a free floating state, which is a problem for stability. is preferable.

When the towing process and the detachable column mounting process are completed, by injecting ballast water into at least one of the ballast tank 22 of the tension mooring floating body 5 before the tension mooring and the detachable column 43, as shown in FIG. The tension mooring floating body 5 is lowered while the upper end of the column 43 is exposed above the water surface 101 . This process is also called subsidence process. In the subsidence process, the vertical distance D4 between the bottom of the tension mooring floating body 5 before tension mooring and the seabed mooring section 9 on the seabed 103 shown in FIG. Sink the tension mooring floating body 5 to a depth shorter than

Next, as shown in FIG. 2(b), the tension mooring floating body 5 before the tension mooring that has sunk is connected to the seabed mooring section 9 in a relaxed state by the tension mooring cable 7. As shown in FIG. Specifically, one end of the tension mooring cable 7 is tied to a hook or ring (not shown) provided at the bottom of the floating column 21 and the submerged columns 23 and 25 of the tension mooring floating body 5 before tension mooring as shown in FIG. The other end of the tension mooring cable 7 is tied to a hook or ring (not shown) provided on the portion 9 . This step is also called a connecting step. The relaxed state here means a state in which no tension is generated in the tension mooring rope 7 due to the buoyancy of the tension mooring floating body 5 before tension mooring.
In the settling process, the tension mooring floating body 5 before tension mooring is lowered to a depth where the vertical distance D4 shown in FIG. Therefore, the tension mooring cable 7 is inevitably in a relaxed state immediately after the connecting step.
Further, the seabed mooring part 9 is installed on the seabed 103 in advance before the connection process is started.

Next, by draining ballast water from at least one of the ballast tanks (not shown) of the tension mooring floating body 5 before tension mooring or the attachment/detachment column 43 and floating the tension mooring floating body 5, the tension mooring floating body 5 is suspended as shown in FIG. 2(c). The mooring floating body 5 is placed in a tension mooring state. The vertical height to float is such that the vertical distance between the tension mooring floating body 5 and the seabed mooring section 9 on the seabed 103 is the length D5 of the tension mooring cable 7, as shown in FIG. 2(c). As a result, the tension mooring cable 7 is pulled by the buoyancy of the tension mooring floating body 5 to generate tension, and the tension mooring floating body 5 is placed in a tension mooring state. This step is also called a tension mooring step.

After the tension mooring process is completed, the tension mooring floating body 5 is tension moored in the offshore wind power generation facility 1 so that the position is held at the mooring point and stabilized, so there is no need to provide the detachable column 43 to ensure stability. . Therefore, after the tension mooring process is completed, the detachable column 43 is removed from the column support portions 45 of the submerged columns 23 and 25 as shown in FIG. 2(c). This process is also called a detachable column removing process.

The detachable column removing step is preferably a step of removing the detachable column 43 after the detachable column 43 has neutral buoyancy by pouring ballast water into and out of the detachable column 43 as shown in FIG. 2(c).
By removing the detachable column 43 after setting the detachable column 43 to neutral buoyancy, when the buoyancy acting on the detachable column 43 is larger than gravity, the detachable column 43 floats at the moment of removal and the tension mooring floating body 5 is suspended. and mooring equipment. In addition, the load required for moving the detached attachment/detachment column 43 can be reduced compared to the case where gravity is greater than buoyancy.

The detachable column 43 removed in the detachable column removing step may be discarded, or may be scrapped and recovered as a resource. However, it may be used for tension mooring of other tension mooring floating bodies 5. Specifically, the detached detachable column 43 is towed or mounted on a work boat or barge and moved to the vicinity of another tension mooring floating body 5 before tension mooring in the process before or after the towing process. Attached to the submerged columns 23, 25 of another tension mooring floating body 5 before tension mooring, as indicated by arrow B in 2(d). Thereby, the detachable column 43 is shared by the plurality of tension mooring floating bodies 5 when the plurality of tension mooring floating bodies 5 are tension moored.
Thus, when a plurality of tension mooring floating bodies 5 are moored in close proximity in a specific sea area, one set of detachable columns 43 may be shared by the plurality of tension mooring floating bodies 5 .

As a result, the number of detachable columns 43 used when tension mooring a plurality of tension mooring floating bodies 5 can be reduced to a minimum of one set, compared to the case where the detachable columns 43 are prepared for each tension mooring floating body 5.例文帳に追加If the number of detachable columns 43 can be reduced, the costs required for disposal and scrap can also be reduced. In particular, the offshore wind power generation equipment 1 needs to be installed in a sea area where strong winds blow stably compared to land, but since such a sea area has a certain extent, the offshore wind power generation equipment 1 can be installed in one sea area. It is possible to increase the amount of power generation by installing multiple units rather than installing only one unit. Therefore, when one set of detachable columns 43 is shared by a plurality of tension mooring floating bodies 5, the movement distance when detaching the detachable columns 43 from one tension mooring floating body 5 and installing it on another tension mooring floating body 5 may be short. , the effect of sharing the detachable column 43 is high.

The detachable column 43 removed in the detachable column removal step may be floated on the sea and used as a workbench for the tension mooring floating body 5 instead of being attached to the submerged columns 23 and 25 of the other tension mooring floating body 5 . The tension mooring floating body 5 that requires a workbench may be the tension mooring floating body 5 itself from which the detachable column 43 is removed, or another tension mooring floating body 5 on which tension mooring work is to be performed. When the detached detachable column 43 is used as a working table for another tension mooring floating body 5 to be tension moored from now on, the detached detachable column 43 is attached to the other tension mooring floating body 5 as shown by arrow C in FIG. 2(d). or towed to the vicinity of a work boat or barge, moved and then floated. After that, the lifted detachable column 43 is used as a table for temporarily placing the tension mooring cable 7 during tension mooring or as a table for installing equipment for letting out the tension mooring cable 7 to the seabed 103 .
Thus, the detachable column 43 removed from the tension mooring floating body 5 may be used as a workbench for the tension mooring floating body 5 .
As a result, the detachable column 43 removed from the tension mooring floating body 5 can be used as a workbench when installing the offshore wind power generation equipment 1 without immediately discarding or scrapping it. In addition, there is no need to separately prepare a workbench for tension mooring of other tension mooring floating bodies 5. - 特許庁
Note that the offshore wind power generation equipment 1 after the detachable column removal step is completed may start generating power.
The above is a brief description of the procedure for installing the offshore wind power generation facility 1 according to the first embodiment.

Thus, according to the first embodiment, the tension mooring floating body 5 of the offshore wind power generation facility 1 is provided with one flotation column 21 and two submerged columns 23, 25 whose upper end is lower than the flotation column 21, and the submerged column 23 , 25 includes a column support 45 that supports the detachable column 43 .

In this configuration, the vertical height of the upper ends of the submerged columns 23, 25 is lower than the upper end 21c of the floating column 21, thereby lowering the center of gravity of the tension mooring floating body 5 and ensuring stability. Furthermore, before the tension mooring floating body 5 is tension moored, the detachable columns 43 are mounted on the upper ends of the submerged columns 23 and 25, and the upper ends of the detachable columns 43 are exposed above the water surface 101, so that the submerged columns 23 and 25 are submerged. The stability of the tension mooring floating body 5 is secured while it is left. In the tension mooring state, by removing the detachable column 43 with the submerged columns 23, 25 submerged, the submerged columns 23, 25 are submerged to minimize the influence of external force due to wind and waves, and the tension mooring floating body 5 due to waves is minimized. To secure buoyancy in a submerged part while preventing fluctuations in buoyancy.
In addition, by making the vertical height of the upper ends of the submerged columns 23 and 25 lower than the upper end of the floating column 21, the submerged columns 23 and 25 are made shorter than the floating column 21, and the weight of the tension mooring floating body 5 is reduced. To suppress an increase in manufacturing cost by making it as small as possible.
Therefore, the tension mooring floating body 5 can ensure stability in a state before being tension moored, and can be made lightweight and low cost.

Next, the structure of the offshore wind power generation facility 1a provided with the tension mooring floating body 5a according to the second embodiment will be described with reference to FIG.
The second embodiment differs from the first embodiment in that the upper ends of the submerged columns 97 and 99 are exposed above the water surface 101 and the detachable column 43 is not mounted.
In the second embodiment, elements that perform the same functions as in the first embodiment are denoted by the same numbers, and mainly different parts from the first embodiment will be described.

As shown in FIG. 7, the offshore wind power generation facility 1a according to the second embodiment includes a tension mooring floating body 5a. Like the tension mooring floating body 5, the tension mooring floating body 5a floats on the sea, supports the wind power generation equipment 3 on the part above the water surface 101, can pour and discharge ballast water, and has a seabed mooring section 9 which is a mooring facility on the seabed 103. It is a floating body connected by a tension mooring cable 7. The tension mooring floating body 5a is held in a tension mooring state in which the tension mooring cable 7 is tensioned by the buoyancy of the floating body. In addition, the tension mooring floating body 5a adjusts the tension of the tension mooring cable 7 by adjusting the buoyancy by pouring and discharging ballast water, and holds the position.
As shown in FIG. 7, the tension mooring floating body 5a has a columnar shape extending in the vertical direction, and the upper end 21c is exposed above the water surface 101 both in the tension mooring state and in the non-tension mooring state. A levitation column 21 on which the wind power generation equipment 3 is installed is provided.
The tension mooring floating body 5a also comprises submerged columns 97,99.
The submerged columns 97 and 99 have the same structure as the submerged columns 23 and 25 of the first embodiment, are connected to the floating column 21 and have upper ends lower than the upper ends 21 c of the floating columns 21 . However, it is different from the submerged columns 23 and 25 in that it has a structure in which the upper end is exposed above the water surface 101 during tension mooring. The submerged columns 97 and 99 have their upper ends exposed above the water surface 101 even in a state in which they are not tensely moored, such as during towing or in preparation for mooring.

The vertical height at which the upper ends of the submerged columns 97, 99 are exposed above the water surface 101 during tension mooring is such that the entire submerged columns 97, 99 are not submerged when waves strike the submerged columns 97, 99. is preferred. Specifically, it should be at least higher than the average significant wave height of the sea area where the offshore wind power generation facility 1 is installed, and preferably higher than the maximum significant wave height. Furthermore, it may be a height obtained by multiplying the average significant wave height or the maximum significant wave height by a desired safety factor. The same applies to the vertical height at which the upper ends of the submerged columns 97, 99 are exposed above the water surface 101 in a non-tension mooring condition such as during towing or in a mooring readiness condition.
Further, since the submerged columns 97 and 99 do not mount the detachable column 43, there is no member corresponding to the column support portion 45 of the first embodiment.
Except for the fact that the upper ends of the submerged columns 97, 99 are exposed above the water surface 101 and that the detachable columns 43 are not mounted on the submerged columns 97, 99, the structure of the tension mooring floating body 5a is the same as that of the tension mooring of the first embodiment. It is the same as the floating body 5. For example, the structures of the floating column 21, the pontoons 29, 31, 32 and the braces 33, 35 of the tension mooring floating body 5a are the same as those of the tension mooring floating body 5 of the first embodiment. The procedure of the tension mooring method for the tension mooring floating body 5a is also the same as the tension mooring method for the tension mooring floating body 5 according to the first embodiment, except that the detachable column 43 is not attached or detached.

In this configuration, the height of the submerged columns 97 and 99 in the vertical direction is lower than that of the floating column 21 to lower the center of gravity of the tension mooring floating body 5, and the tension mooring floating body 5a is exposed above the water surface 101 even when tension mooring is not performed. ensure the stability of the
In addition, by making the vertical height of the upper ends of the submerged columns 23 and 25 lower than the upper end of the floating column 21, the submerged columns 23 and 25 are made shorter than the floating column 21, and the weight of the tension mooring floating body 5 is reduced. To suppress an increase in manufacturing cost by making it as small as possible.

Thus, according to the second embodiment, the tension mooring floating body 5 of the offshore wind power installation 1 comprises one flotation column 21 and two submerged columns 97 , 99 whose upper ends are lower than the flotation column 21 . Therefore, the tension mooring floating body 5a can ensure stability before installation, and is lightweight and low cost.

Which of the first embodiment and the second embodiment is adopted may be appropriately selected in consideration of the weather conditions of the sea area where the offshore wind power generation facilities 1 and 1a are to be installed and workability during installation.
For example, in the first embodiment, only the upper ends 21c of the levitation columns 21 and the braces 33, 35 are exposed above the water surface 101 and affected by waves in the first embodiment. Therefore, the first embodiment is advantageous when the offshore wind power generation facility 1 is installed in a sea area where the tension mooring floating body 5 is frequently hit by waves. Further, in the first embodiment, a work boat is required for the attachment/detachment work of the attachment/detachment column 43 . Therefore, it is suitable for the offshore of countries and regions where there is a work boat suitable for performing the detachment work and inexpensive to use, for example, a relatively small work boat having a ship position fixed point holding function and a crane capable of handling the attachment and detachment tool of the attachment and detachment column 43. This is advantageous when installing the offshore wind power generation equipment 1 .
On the other hand, the second embodiment does not require detachment work for the detachable column 43, which is advantageous in terms of workability when installing the offshore wind turbine generator 1a at the mooring point. In addition, since the detachable column 43 does not need to be attached and detached, it is advantageous when the offshore wind turbine generator is installed offshore in a country or region where there are no low-cost work boats suitable for the detachable work.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the embodiments. A person skilled in the art will naturally conceive of various modifications and improvements within the scope of the technical idea of the present invention, and these are also included in the present invention.

1, 1a: offshore wind power generation equipment 3: wind power generation equipment 5, 5a: tension mooring floating body 7: tension mooring cable 9: sea bottom mooring part 11: tower 13: nacelle 15: boss 17: blade 21: floating column 21c: upper end 22 : Ballast tank 23 : Submerged column 25 : Submerged columns 29, 31, 32 : Pontoons 33, 35 : Brace 43, 43a, 43b : Detachable column 45 : Column support 51 : Support side flange 53 : Through hole 55 : Bolt 57 : Detachable column side flange 59 : Bolt insertion hole 61 : Nut 63 : Floor portion 65 : Bulwark 71 : Engagement portion 73 : Hook 74 : Tip 75 : Hook support portion 77 : Rotating shaft 81 : Stud support portion 83 : Stud 84 : Pin 85: socket 86: holes 91, 93: buckling brace 95: braces 97, 99: submerged column 101: water surface 103: seabed

Claims (20)

A floating body that floats on the ocean and supports a wind power generation facility on the surface of the water, is capable of pouring and discharging ballast water, and is connected to a seabed mooring section, which is a mooring facility on the seabed, by tension mooring ropes, and the buoyancy of the floating body is used as described above. A tension mooring floating body held in a tension mooring state in which tension is generated in tension mooring ropes,
at least one levitation column in the form of a column extending vertically, the upper end of which is exposed above the water surface, and the wind power generation equipment is installed on the exposed upper end;
It is connected to the levitation column and is completely submerged in water in a tension mooring state, and has a columnar shape extending in the vertical direction, the upper end of which is lower than the upper end of the levitation column. two or more submerged columns with column supports that expose the
A tension mooring floating body comprising: 2. A tension mooring floating body according to claim 1, comprising one said flotation column and two said submerged columns. 3. A tension mooring floating body according to claim 1 or 2, wherein at least one of said float column and said submerged column is cylindrical in profile. a pontoon that extends horizontally and is a member that connects the lower ends of the floating columns to the lower ends of the submerged columns and the lower ends of the submerged columns;
The tension mooring floating body according to any one of claims 1 to 3, wherein the floating column and the submerged column have bottom surfaces at the same vertical height. a pontoon that extends horizontally and is a member that connects the lower ends of the floating columns to the lower ends of the submerged columns and the lower ends of the submerged columns;
3. The tension mooring floating body according to claim 2, having a shape of an equilateral triangle with one floating column and two submerged columns as vertices and sides of said pontoons in a plan view. 6. The tension mooring floating body according to claim 5, further comprising a brace projecting obliquely downward from the upper end of the levitation column and connecting the upper end of the levitation column and the submerged column or the pontoon. 7. The method of claim 6, wherein the two braces connect the upper end of the levitation column and the two submerged columns, respectively, to form a triangular pyramid shape with sides of the levitation column, the brace and the pontoon. tension mooring float. 8. A tension mooring floating body according to claim 6 or 7, wherein said brace is cylindrical. The floating body structure for mooring preparation, wherein the detachable column is supported by the column support portion of the submerged column of the tension mooring floating body according to any one of claims 1 to 8. A detachable column detachably supported by the column support portion of the submerged column of the tension mooring floating body according to any one of claims 1 to 8, and having an upper surface exposed above the water surface in the supported state. 11. The detachable column according to claim 10, which is a watertight structure with a horizontal cross-section whose axial direction is oriented vertically and whose length from said axis to a point on the outer edge is constant or not constant. a watertight floor having a horizontal cross-section with a constant or variable length from said axis whose axial direction is oriented vertically to a point on the outer edge;
11. The detachable column according to claim 10, further comprising a bulwark erected on the outer periphery of the upper surface of the floor, and having a connection portion with the floor and a bulwark having a watertight outer periphery. a columnar floor of a watertight structure having a horizontal cross-section with a constant or variable length from the axis whose axial direction is oriented vertically to a point on the outer edge;
11. The detachable column according to claim 10, further comprising a bulwark erected on the outer periphery of the upper surface of the floor, and having a connection portion with the floor and a watertight outer periphery. The column support portion
The tension mooring floating body according to any one of claims 1 to 8, wherein the structure rigidly connects the submerged column and the detachable column. A tension mooring floating body according to any one of claims 1 to 8 and 14;
A seabed mooring section, which is a mooring facility installed on the seabed,
a tension mooring line that connects the seabed mooring section and the tension mooring floating body in a tension mooring state in which tension is generated by the buoyancy of the tension mooring floating body;
a wind power generation facility that is supported by the portion exposed above the water surface of the tension mooring floating body and that converts wind power into electric power;
An offshore wind power generation facility with A tension mooring method for a tension mooring floating body according to any one of claims 1 to 8 and 14,
A towing process of towing the tension moored floating body before tension mooring to the mooring point over the sea;
a detachable column attaching step, which is performed before and after the towing step and attaches the detachable column to the submerged column so that the top end of the column is exposed above the water surface;
It is carried out after the detachable column mounting step, and by injecting ballast water into at least one of the tension mooring floating body and the detachable column before tension mooring, the upper end of the detachable column is exposed above the water surface. a subsidence step of submerging the tension mooring floating body;
a connecting step of connecting the tension mooring floating body that has sunk before tension mooring to the seabed mooring section in a relaxed state with the tension mooring rope;
a tension mooring step in which ballast water is discharged from at least one of the tension mooring floating body and the detachable column before tension mooring, the tension mooring floating body is floated, and the tension mooring rope is tensioned to bring the tension mooring state into a tension mooring state; ,
a detachable column removing step of removing the detachable column from the column support portion of the submerged column after the completion of the tension mooring step;
A tension mooring method for a tension mooring floating body, characterized by: The detachable column removing step includes:
17. The tension mooring method for a tension mooring floating body according to claim 16, wherein the tension mooring method for a tension mooring floating body according to claim 16, comprises a step of detaching the detachable column after setting the detachable column to neutral buoyancy by pouring ballast water into and draining the detachable column. By attaching the detachable column removed in the detachable column removing process to the submerged column of the other tension mooring floating bodies in the process before and after the towing process, the tension mooring of the plurality of tension mooring floating bodies can be carried out. 18. A method of tension mooring of a tension mooring floating body according to claim 16 or 17, wherein a detachable column is shared by a plurality of said tension mooring floating bodies. The tension mooring method for a tension mooring floating body according to any one of claims 16 to 18, wherein the detachable column removed in the detachable column removing step is floated on the sea and used as a workbench for the tension mooring floating body. A floating body that floats on the ocean and supports a wind power generation facility on the surface of the water, is capable of pouring and discharging ballast water, and is connected to a seabed mooring section, which is a mooring facility on the seabed, by tension mooring ropes, and the buoyancy of the floating body is used as described above. A tension mooring floating body held in a tension mooring state in which tension is generated in tension mooring ropes,
one levitation column, which has a columnar shape extending in a vertical direction, the upper end of which is exposed above the water surface, and the wind power generation equipment is installed on the exposed upper end;
two submerged columns that are connected to the floating columns and that have upper ends exposed above the water surface and vertically extending columnar shapes, the upper ends of which are lower than the upper ends of the floating columns;
with
A tension mooring floating body characterized by being constructed so as to adjust tension by adjusting buoyancy by filling and discharging ballast water.

Images