Installation method for floating type structure

Abstract

To provide an installation method for a floating type structure capable of stably installing the floating type structure.SOLUTION: An installation method for a floating type structure 100 includes at least the following steps: to tow the floating type structure 100 to its installing location; to install a temporary auxiliary floating body 20 on the floating type structure 100; to precipitate the floating type structure 100 to a prescribed depth by pouring water into a ballast tank 10 of the floating type structure 100; to connect a mooring cable 41 connected to an anchor 40 to the floating type structure 100 at the prescribed depth; to drain the ballast tank 10 after the mooring cable 41 is connected to the floating type structure 100; and to remove the temporary auxiliary floating body 20 after the ballast tank 10 is drained.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for installing a floating structure on the ocean. [Background technology]

[0002] Due to the growing need for offshore wind power generation, which is a form of clean energy, various methods for installing floating structures have been proposed. For example, Patent Documents 1 and 2 disclose inventions of floating wind power generation equipment in which a power generation device consisting of a windmill or the like is supported by a floating structure.

[0003] For example, a TLP (Tension Leg Platform) floating structure is characterized by its stability being ensured by tension mooring using tendons (tension mooring ropes) and anchors fixed to the seabed. In the construction process, in order to join the floating body and the tendons, it is necessary to inject ballast water into the ballast tanks inside the floating body and sink the floating body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5565803 [Patent Document 2] Patent No. 5738431 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as shown in FIG. 1, although the floating structure 100 maintains a stable posture when floating naturally, when ballast water is poured into the ballast tank 10 and the structure sinks, the structure becomes unstable and it becomes difficult to maintain a stable posture.

[0006] In the conventional method, a dedicated ship as shown in FIG. 8 of Patent Document 1 is manufactured and configured to hold the floating structure, or columns (22a, 22b, 22c) as shown in FIG. 1 of Patent Document 2 are provided to stabilize the floating structure.

[0007] However, if such a dedicated vessel were to be constructed, the construction costs would be extremely high, and since the vessel is not versatile, a different dedicated vessel would need to be constructed for each project, which would be extremely uneconomical.

[0008] In addition, if the column integrated with the floating structure is designed to remain partly above the water surface even after installation is complete, the column will be unnecessarily high above the water surface after operation, and will become unstable due to the effects of waves. Furthermore, taking measures to prevent this will lead to the floating structure becoming larger, which is uneconomical.

[0009] In view of the above problems, an object of the present invention is to provide a method for installing a floating structure, which enables a floating structure to be stably installed. [Means for solving the problem]

[0010] The invention related to (1) is a method for installing a floating structure, comprising at least the steps of towing a floating structure to an installation site of the floating structure, installing a temporary auxiliary float on the floating structure, injecting water into a ballast tank of the floating structure to sink the floating structure to a predetermined depth, connecting a mooring line connected to an anchor to the floating structure at the predetermined depth, draining the ballast tank after the mooring line is connected to the floating structure, and removing the temporary auxiliary float after draining the ballast tank.

[0011] The invention related to (2) is a method for installing a floating structure described in the above (1), wherein the temporary auxiliary float is a structure that is watertight and can be attached and detached.

[0012] The invention related to (3) is a method for installing a floating structure described in (1) or (2) above, wherein the floating structure is a TLP (tension leg platform) type floating structure and the mooring line is a tension mooring line. Effect of the Invention

[0013] According to the present invention, by attaching a temporary auxiliary float before the floating structure sinks, it is possible to ensure the stability of the floating structure during sinking.Furthermore, after the sinking is completed and the mooring lines are connected, the temporary auxiliary float is removed, thereby minimizing the impact of waves on the floating structure after it is put into service. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram illustrating a problem in the related art. [Diagram 2] FIG. 2 is a side view showing a towing mode of a floating structure in one embodiment of the present invention. [Diagram 3] FIG. 2 is a side view illustrating the installation of a temporary auxiliary floating body on a floating structure in one embodiment of the present invention. [Figure 4] FIG. 2 is a side view illustrating a sinking mode of a floating structure in one embodiment of the present invention. [Diagram 5] FIG. 2 is a side view illustrating a manner in which a tendon is connected to a floating structure in one embodiment of the present invention. [Figure 6] FIG. 2 is a side view illustrating the tensioning mode of the tendon in one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, one embodiment of the method for installing a floating structure of the present invention will be described with reference to the drawings, taking a TLP (tension leg platform) type floating structure as an example.

[0016] 2 shows a state in which the floating structure 100 is towed by a tugboat 30 to an installation position of the floating structure 100. The floating structure 100 of this embodiment is a TLP (tension leg platform) type floating structure, and an anchor 40 is installed on the seabed at the installation position, and a tendon 41 (tension mooring rope) is connected to the anchor 40.

[0017] During towing, water is not poured into the ballast tanks 10 of the floating structure 100, so that the floating structure 100 can be towed stably on the ocean.

[0018] 3, the floating structure 100 is towed to the installation position of the floating structure 100 and connected to a plurality of tugboats 30 or the like to be held at a fixed position. Then, a detachable temporary auxiliary float 20 is connected to the floating structure 100.

[0019] In this embodiment, a cylindrical structure is connected as the temporary auxiliary float 20, but it is not necessarily limited to such a product, and various floats can be used alone or by connecting multiple floats depending on the required buoyancy to form the temporary auxiliary float 20. In addition, the floating structure 100 may be assisted by hoisting it with a crane ship as necessary.

[0020] 4, water is poured into the ballast tank 10 of the floating structure 100 to gradually sink the floating structure 100 to a predetermined depth. At this time, at least a part of the temporary auxiliary float 20 rises above the water surface, and the floating structure 100 can be stably sinked by the buoyancy of the temporary auxiliary float 20.

[0021] Next, as shown in FIG. 5, a tendon is connected to the floating structure 100 that has been lowered to a predetermined depth, and then the ballast tank 10 of the floating structure 100 is drained.

[0022] Then, as shown in Fig. 6, the temporary auxiliary float 20 is removed. When removing the temporary auxiliary float 20, in addition to manual work by a diver, an ROV (underwater drone, etc.) or an automatic slinging and releasing device can be used. As a result, the tendon is tensioned by the buoyancy of the floating structure 100.

[0023] As described above, by having at least the steps of towing the floating structure 100 to the installation site of the floating structure 100, installing the temporary auxiliary float 20 on the floating structure 100, filling the ballast tank 10 of the floating structure 100 with water to sink the floating structure 100 to a predetermined depth, connecting the mooring line 41 connected to the anchor 40 to the floating structure 100 at the predetermined depth, draining the ballast tank 10 after the mooring line 41 is connected to the floating structure 100, and removing the temporary auxiliary float 20 after draining the ballast tank 10, it is possible to install the floating structure 100 stably at a significantly lower cost than in the conventional method, without the columns being present above the water surface and being affected by waves.

[0024] (Another embodiment) Although the method for installing the floating structure 100 according to this embodiment has been described above, the present invention is not necessarily limited to the above-described embodiment.

[0025] For example, the above-described embodiment has been described using a TLP (tension leg platform) type floating structure as an example, but the present invention is not limited to this, and the present invention can also be applied when installing a catenary type floating structure.

[0026] In addition, in the illustrated embodiment, a center column type floating structure 100 has been described as an example, but the shape is not necessarily limited to this type, and the present invention can be applied to the sinking of columns of various shapes.

[0027] The scope of the present invention is defined by the claims, not by the description of each embodiment above, and includes all modifications within the meaning and scope of the claims. The specific materials, dimensions, shapes, etc. described in the above embodiments can be modified within the scope of the present invention. [Explanation of symbols]

[0028] 10. Ballast Tank 20 Temporary auxiliary floating body 30 Tugboat 40 Anchor 41 Tendon (tension mooring rope) 100 Floating Structures

Claims

1. towing the floating structure to a site for installing the floating structure; A step of installing a temporary auxiliary floating body on the floating structure; Injecting water into a ballast tank of the floating structure to lower the floating structure to a predetermined depth; connecting a mooring line connected to an anchor to the floating structure at the predetermined depth; discharging the ballast tank after the mooring lines are connected to the floating structure; and removing the temporary auxiliary floating body after discharging the ballast tank. A method for installing a floating structure comprising the steps of:

2. The temporary auxiliary floating body is a structure that is watertight and can be attached and detached. A method for installing a floating structure according to claim 1.

3. The floating structure is a tension leg platform (TLP) type floating structure, The mooring line is a tension mooring line. A method for installing a floating structure according to claim 1 or 2.

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