Large-tonnage pre-tensioning device suitable for floating foundation anchoring system

Abstract

The invention discloses a large-tonnage pre-tensioning device suitable for a floating foundation anchoring system, and belongs to the technical field of wind power facility installation, the large-tonnage pre-tensioning device comprises a buoy body and at least three pre-tensioning fins, the pre-tensioning fins are uniformly distributed on the outer side face of the buoy body, one end of an anchor chain penetrates through the pre-tensioning fins, and the other end of the anchor chain is connected with an anchor. According to the anchor chain pre-tensioning device, the symmetry of a floating type foundation anchor cable can be utilized, the pre-tensioning device can be installed on a ship, preliminary pre-tensioning is completed through a 50t winch on the device, and then tension about 500t is gradually provided by a crane. By designing the proper structural strength and the chain controller, the pre-tension requirement of the required tonnage can be provided. The method can be suitable for pretensioning various symmetric floating foundation anchoring systems on the sea, the cost of a construction ship machine can be greatly reduced, the construction period is shortened, and the construction utilization efficiency of a short operation window period on the sea is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wind power facility installation, and in particular to a large-tonnage pre-tensioning device suitable for a floating foundation anchoring system. Background Art

[0002] With the development of offshore wind power, there is a trend of moving into the deep sea. In offshore areas with a water depth greater than 50 m, the cost of fixed pile foundations or jacket foundations will be very high, and floating foundation structures are a more ideal choice. This foundation serves as a platform for installing wind turbines and is anchored to the seabed with a mooring system. It is relatively low in cost and easy to transport. The floating foundation must have buoyancy to support the weight of the wind turbine and be able to suppress tilting, shaking and normal movement within acceptable limits.

[0003] For example, Patent No. 201620125832.0 introduces a deep-sea semi-submersible floating offshore wind power platform, which is fixed by a floating foundation platform and anchor chains around it to prevent the wind power platform from tilting and shaking.

[0004] When installing a floating platform, it is necessary to first use a tugboat to tow the floating platform to the installation location at sea, and then lower the anchor chain and anchor hook to anchor the platform at sea. Since the floating platform floats on the sea, if the floating platform is directly tightened at sea, first, the drift of the floating platform is not conducive to applying a large pulling force, and secondly, the required pulling force is huge, and the installation cost is high; direct full-tonnage pre-tensioning on the floating wind turbine also takes a long time. At this time, there are many ships and machines on site, and the on-site ship daily rate is very high. Now the floating platform is placed on the construction ship first, and the anchor chain is pre-tensioned and tightened first to ensure that the anchor chain is straightened throughout the whole process, and the pile anchor suction mud is pre-tensioned to form the reverse arc under the anchor mud to ensure that the large grip anchor grip meets the design requirements. The high-strength fiber cable also needs to be pre-tensioned before use to reduce the lifting amount during subsequent use. After the pre-tensioning is completed, the anchor chain is loosened and placed on the seabed. Later, the floating platform is towed to the installation location, and then the anchor chain is connected to the floating platform and tightened, which reduces the difficulty of installing the floating platform.

[0005] At present, the anchoring of offshore floating foundations mainly includes large-hold anchors, pile anchors, suction anchors, gravity anchors, tension legs and other methods. When installing large-hold anchors, the anchor chain needs to be pre-tensioned. The large-hold anchor can move along a part of the designed route and be partially or completely buried in the seabed, and can provide sufficient holding force later. The large-hold anchor foundation often requires a pre-tension of more than 300 tons. As the capacity of the subsequent wind turbine monomer gradually increases, the pre-tension will also become larger and larger. The connection point between the pile anchor and the anchor chain is often below the mud surface, and a large tonnage is also required for pre-tensioning to form an anti-catenary with the mud layer to ensure that the anchor chain is tightened on the windward side of the typhoon during subsequent use, and there will be no loosening of the anchor chain later. Depending on the influence of the surface mud and the depth of the pile-anchor connection point, it is often necessary to achieve a tension of more than 200 tons at the pile anchor to pull out the anti-catenary.

[0006] With the gradual application of high-strength soft cables, high-strength polymer cables and high-strength nylon cables themselves often require a tensile force of more than 300T or even more than 500T to pre-tension them and release part of the growth before they can be used normally.

[0007] At present, the layout of floating foundation anchor systems is symmetrical. If each anchor cable is pre-tensioned separately, the construction vessel needs to provide an anchor support capacity of more than 400T, which is also very difficult for the current large floating cranes, especially since the anchor chains have three different directions and require multiple anchoring and dropping, which reduces construction efficiency. A single 16,000KW high-powered tugboat can only provide an effective pulling force of about 200 tons, and the pulling force provided by the tugboat is very unstable. Therefore, it is not suitable for providing a pre-tension of more than 200T. Both large floating cranes and high-powered tugboats are very expensive and are not suitable for the general direction of floating wind turbine power generation and grid parity. Summary of the invention

[0008] The technical problem to be solved by the present invention is to provide a large-tonnage pre-tensioning device for a floating foundation anchoring system, which provides a large-tonnage (not less than 500t) systematic anchor chain pre-tensioning and releasing solution, and integrates a detachable and adjustable pre-tensioning buoy-type pre-tensioning device to solve the technical problems of offshore anchor pre-tensioning and stabilization of floating structures such as large floating wind turbine foundations and various types of anchored marine engineering products.

[0009] In order to solve the above technical problems, the technical solution adopted by the present invention is: a large-tonnage pre-tensioning device suitable for a floating foundation anchoring system, comprising a buoy body and pre-tensioning fins, at least three of which are evenly distributed on the outer side of the buoy body, one end of the anchor chain passes through the pre-tensioning fins, and the other end of the anchor chain is connected to the anchor.

[0010] Preferably, the buoy body is an irregular cylinder, and a section is arranged on one side of the buoy body.

[0011] Preferably, the pre-tensioning fin includes a chain stopper, a guide rail roller, a reinforced support plate and a longitudinal baffle. There are two longitudinal baffles, which are arranged opposite to each other. The guide rail roller is transversely arranged between the two longitudinal baffles. The reinforced support plate is arranged on the top of the two longitudinal baffles. The chain stopper is fixed on the top of the reinforced support plate. The center of the reinforced support plate is opened, and the anchor chain passes through the center hole of the reinforced support plate and then passes through the chain stopper.

[0012] Preferably, at least one hole is opened on the longitudinal baffle to reduce the deadweight of the longitudinal baffle and serve as an observation hole.

[0013] Preferably, one side edge of the longitudinal baffle is fixed on the buoy body, and both upper and lower ends of the outer side edge are chamfered to prevent scratches.

[0014] Preferably, the chain stopper is a controllable one-way locking structure, which opens to allow the anchor chain to pass when the crane pulls the anchor chain upwards, and automatically locks the anchor chain under the action of gravity when the anchor chain is lowered.

[0015] Preferably, three pre-tension fins are provided, and the angles between adjacent pre-tension fins are all 120°, corresponding to the design of the anchor chain of a floating wind turbine.

[0016] A method for using a large-tonnage pre-tensioning device suitable for a floating foundation anchoring system comprises the following steps: (1) Use a construction vessel to transport the pre-tensioning device to the predetermined installation location, fix the pre-tensioning device on the stern side or the midship side, and align the cutting surface of the pre-tensioning device with the edge of the ship; (2) Use a 50T winch to pull the anchor chain through the chain stopper. The other end of the anchor chain is connected to the anchor. The winch first completes the initial pre-tensioning. Then use the crane to load the three anchor chains in the 120° direction to the designed tonnage step by step. At the same time, tighten the three anchor chains. After tightening, keep them stable for half an hour. Depending on the tightness of the anchor chains, control the crane to continue tightening the anchor chains. (3) After tightening the anchor chain, let it stand and confirm that the anchor chain and anchor have no displacement. Open the chain stopper to loosen the three anchor chains step by step until they reach 0 tonnage. Then put the anchor chains into the seabed one by one. At this time, the pre-tensioning of the anchor on the seabed has been completed. The pre-tensioning has the following effects: the pile anchor tension test has been completed, and the pile anchor chain has formed an arc under the mud; the high holding power anchor tension test has been completed; and the high-strength cable pre-tensioning has been completed; (4) The crane on the construction vessel hoists the anchor chain to the floating platform for offshore wind power installation, and then hoists the anchor chain back to the chain stopper on the floating platform for offshore wind power installation and passes it through the chain stopper before tightening the anchor chain. Repeat the above operation for the remaining anchor chains and tighten them in sequence; (5) After the construction is completed, the construction vessel carries the pre-tensioning device back to the next installation location.

[0017] By adopting the technical solution of the present invention, the following beneficial effects can be obtained: (1) Strong applicability: The device is suitable for various floating foundation anchoring systems. It can solve the problems of pre-tensioning and stabilizing the offshore anchor chains of floating structures such as large floating wind turbine foundations in medium water depths and those greater than 50 meters, various types of anchored marine engineering products, and the coordination of different anchoring construction methods.

[0018] (2) Improve construction efficiency: In the short operation window at sea, it can complete and provide stable anchor chain pre-tensioning force in a short time, and complete the pre-tensioning of 3 anchor chains each time. The construction efficiency is improved. At the same time, compared with the traditional anchoring system, this device avoids the use of ship anchoring or thrust to resist pre-tensioning force through large-tonnage systematic anchor chain pre-tensioning, which greatly reduces the requirements for ship performance. This system uses a large-tonnage crane to pre-tension the anchor chain.

[0019] (3) Stable and accurate pre-tension: The device controls the pre-tensioning more accurately, and the horizontal forces of the three anchor chains roughly offset each other. The pre-tensioning device can provide very stable and accurate pre-tensioning, which can theoretically control a single anchor chain, and provide centimeter-level precision control by adjusting the ship's ballast.

[0020] (4) Convenient conversion: The chain stopper cutting and installation process is convenient and quick, and can be completed on the side of the ship or on the deck at the construction site. The replacement efficiency is high and the cost is low.

[0021] (5) No need for diving: By properly setting up the towing rope, all operations are carried out on the deck of the main operation vessel, without the need for diving.

[0022] (6) With this device, only a medium-sized floating crane vessel of less than 1,000 tons is needed to complete the laying and pre-tensioning of the anchor chain. And the three anchor chains can be pre-tensioned simultaneously. It effectively reduces the requirements for ship machinery and equipment, improves the efficiency of anchor construction, saves the installation cost of floating wind turbines, and is conducive to the large-scale assembly line construction of floating wind turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following is a brief description of the contents and symbols in the drawings of this specification: Figure 1 It is a schematic diagram of the structure of the buoy body and the pre-tensioned fin; Figure 2 It is a structural schematic diagram of the pre-tensioned fin; Figure 3 It is a top view of the buoy body and the pre-tensioned fin; Figure 4 It is the front view of the buoy body and the pre-tensioned fin; Figure 5 A schematic diagram of the structure for installing the buoy body and the pre-tensioned fin on an engineering vessel; The markings in the above figures are: 1. buoy body; 2. pre-tensioned fin; 21. chain stopper; 22. guide roller; 23. reinforced support plate; 24. longitudinal baffle; 3. anchor chain. DETAILED DESCRIPTION

[0024] The following is a detailed description of the embodiments of the present invention, such as the shapes and structures of the components involved, the relative positions and connection relationships between the components, the functions and working principles of the components, etc., with reference to the accompanying drawings.

[0025] like Figure 1-5 As shown, the large-tonnage pre-tensioning device suitable for the floating foundation anchoring system includes a buoy body 1 and pre-tensioning fins 2. There are at least three pre-tensioning fins 2, which are evenly distributed on the outer side of the buoy body 1. One end of the anchor chain 3 passes through the pre-tensioning fins 2, and the other end of the anchor chain 3 is connected to the anchor. The buoy body 1 is an irregular cylinder, and a section is set on one side of the buoy body 1. After the pre-tensioning device is placed on the ship, the section position is placed corresponding to the ship's side, which can prevent the buoy body 1 from protruding outside the hull of the engineering ship and ensure navigation safety.

[0026] like Figure 2 As shown, the pre-tensioning fin 2 includes a chain stopper 21, a guide roller 22, a reinforcement support plate 23 and a longitudinal baffle 24. Two longitudinal baffles 24 are provided, and the two longitudinal baffles 24 are arranged opposite to each other. The guide roller 22 is transversely arranged between the two longitudinal baffles 24, and the reinforcement support plate 23 is arranged on the top of the two longitudinal baffles 24. The chain stopper 21 is fixedly arranged on the top of the reinforcement support plate 23. The center of the reinforcement support plate 23 is opened, and the anchor chain 3 passes through the center hole of the reinforcement support plate 23 and then passes through the chain stopper 21. At least one hole is opened on the longitudinal baffle 24 to reduce the deadweight of the longitudinal baffle 24 and serve as an observation hole. One side of the longitudinal baffle 24 is fixed on the buoy body 1, and the upper and lower ends of the outer side are chamfered to prevent scratches.

[0027] like Figure 1 , 2 As shown in , 4, the chain stopper 21 is a one-way locking structure. Four limit blocks are arranged on the chain stopper 21. The limit blocks can only be flipped upwards but not downwards. When the crane pulls the anchor chain 3 upwards, the limit blocks flip upwards to release the anchor chain 3. When the anchor chain 3 stops moving, the top of the limit blocks is stuck in the gap in the middle of the anchor chain 3 to lock the anchor chain 3.

[0028] like Figure 1 , 3As shown, three pre-tensioning fins 2 are provided, and the angles between adjacent pre-tensioning fins 2 are all 120°. The pre-tensioning device is installed on the ship, and the anchor chains 3 in three directions of 120° are connected at the same time. The initial pre-tensioning is completed by the 50T winch on the device, and then the crane gradually provides a pulling force of about 500T. The main operating ship itself is not subjected to the horizontal pulling force of the anchoring, but is offset by the three symmetrically distributed anchor cables.

[0029] The chain stopper 21 is used in conjunction with the guide roller 22. The anchor chain 3 passes through the guide roller 22 from the fixed end of the structure and is led to the chain stopper 21. The anchor chain 3 is towed from the seabed to the chain stopper 7 by the traction winch and the traction rope, and the remaining two anchor chains 3 are towed to the chain stopper 21 in turn. Then the anchor chains are tightened one by one and in sections by the floating crane, such as pre-tensioning each anchor chain 3 to 100T, 200T, and 300T in sequence until the required design tonnage is reached, and then stabilized for a period of time, such as 30 minutes. The chain stopper 21 only allows the anchor chain 3 to be retracted, and does not allow it to be withdrawn. The purpose of pre-tensioning is achieved by lifting it a certain distance. After use, the anchor chains 3 are lifted in sequence, and the anchor chains 3 are lowered section by section and placed on the seabed.

[0030] The method for using the large-tonnage pre-tensioning device applicable to the floating foundation anchoring system comprises the following steps: (1) Use a construction vessel to transport the pre-tensioning device to the predetermined installation location and fix the pre-tensioning device at the stern or midship; (2) Use a 50T winch to pull the anchor chain 3 through the chain stopper 21. The other end of the anchor chain 3 is connected to the anchor. The winch first completes the initial pre-tensioning. Then, use the crane to load the three anchor chains 3 in the 120° direction step by step to the designed tonnage (such as 500T) at the same time. At the same time, tighten the three anchor chains 3. After tightening, keep them stable for half an hour. Depending on the tightness of the anchor chains 3, control the crane to continue tightening the anchor chains 3. (3) After tightening the anchor chain 3 and leaving it to stand, after confirming that the anchor chain 3 and the anchor have no displacement, the chain stopper 21 is opened to gradually loosen the three anchor chains 3 until they reach 0 tonnage, and the anchor chains 3 are placed on the seabed in sequence. At this time, the pre-tensioning of the anchor on the seabed has been completed, and the pre-tensioning has the following effects: the pile anchor tension test is completed, and the pile anchor chain 3 has formed an arc under the mud; the large holding force anchor tension test is completed; and the high-strength cable pre-tensioning is completed; (4) The crane on the construction ship hoists the anchor chain 3 to the floating platform for offshore wind power installation, and then hoists the anchor chain 3 to the chain stopper on the floating platform for offshore wind power installation and passes through the chain stopper to tighten the anchor chain 3. Repeat the above operation for the remaining anchor chains 3 and tighten them in sequence; (5) After the construction is completed, the construction vessel carries the pre-tensioning device back to the next installation location.

[0031] When the buoy-type body 1 is in use, one side of the sealing plate needs to be aligned with the side of the hull, and the pre-tensioning fin 2 on the same side needs to be used as a reference to determine whether it extends out of the deck. Since the anchor chain 3 and the entire system will be subjected to a force of hundreds of tons during operation, it can be ensured that the anchor chain 3 does not contact the deck surface during pre-tensioning, thereby avoiding damage to the deck side steel plate and causing unnecessary losses.

[0032] The pre-tensioned fin 2 on the opposite side of the buoy-type body 1 can withstand the axial tension of the anchor chain 3 at a small oblique angle, and is used for anchoring of asymmetric anchor chain 3. The anchoring arrangement of offshore floating foundation structures presents a large angle. Therefore, this design takes into account giving a certain variable inclination angle of the anchor chain 3 while ensuring the structural strength, thereby improving the layout and pre-tensioning efficiency.

[0033] The chain outlet diameter of the chain stopper 21 can be replaced to cope with larger or less commonly used smaller anchor chain diameters. When replacing, only the top reinforcing support plate 23 of the pre-tensioning fin 2 needs to be replaced. The chain stopper 21 is fully penetrated and welded to the vertical reinforcing support plate 23 as an integral part, so it can be replaced to cope with anchor chains of different specifications.

[0034] Three symmetrically arranged anchor chains 3 are connected to the pre-tensioning device, and the pre-tensioning is gradually loaded. The construction vessel itself does not need to provide additional anchor holding force, which greatly reduces the dependence on the ship anchoring or high-powered pre-tensioning tugboat.

[0035] The three symmetrically designed floating structure anchors are pre-tensioned at the same time, and the loading is symmetrical step by step to ensure the stability of the applied load. For example, the design often requires that the pre-tension force be stable for 30 minutes, and the tension deviation is within ±10%. When using large tugboats or propeller thrust, the tension stability deviation is often more than ±20%.

[0036] With the increasing number of high-strength fiber cables used in floating wind turbines, the pre-tensioning force is even required to be up to 500 tons. Through strength analysis, the pre-tensioning device provided this time can achieve a maximum stable pre-tensioning force of 500 tons.

[0037] Floating wind turbines are usually designed with 3-column symmetric 6 anchors or 3-column symmetric 9 anchors. This pre-tensioning device can pre-tension 3 anchor chains at a time. When a single anchor chain is pre-tensioned, 3 completely different anchor positions are required for the pre-tensioning of the 3-column floating body. This pre-tensioning device is expected to greatly save pre-tensioning time. Compared with the direct single pre-tensioning of conventional ships, the construction efficiency is increased by several times.

[0038] By adjusting the installation position of the pre-tensioning device, such as the side of the tail, the anchor chain 3 can be prevented from contacting the hull, and the anchor chain can be prevented from scratching the hull and requiring an additional hull protection device. At this time, the floating crane often has a lifting capacity close to the maximum.

[0039] The whole set of equipment is a machined part connected by steel structure and a small amount of anchor chain 3, with low production cost and short production cycle. It greatly reduces the requirements for the main operation ship. The installation of all anchor systems and the pre-tensioning of up to 500T can be completed on site by using a floating crane within 1000T (using crane pre-tensioning, the pre-tensioning force depends on the crane capacity).

[0040] The diameter of the pre-tensioning device can also be slightly increased, and the compartments can be designed at the same time. It can be towed directly to the construction site and leaned against the side of the floating crane. After symmetrically connecting with the floating anchor, the crane is used for pre-tensioning in sections, and the floating body is towed back by a tugboat after completion, which can save the installation time of the pre-tensioning device and the crane, and is more economical when only a single or a small number of units are used in the wind farm.

[0041] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A large-tonnage pre-tensioning device suitable for a floating foundation anchoring system, characterized in that: It comprises a buoy body and pre-tension fins. There are at least three pre-tension fins, which are evenly distributed on the outer side of the buoy body. One end of the anchor chain passes through the pre-tension fins, and the other end of the anchor chain is connected to the anchor.

2. The large-tonnage pre-tensioning device suitable for a floating foundation anchoring system according to claim 1 is characterized in that: The buoy body is an irregular cylinder, and a section is arranged on one side of the buoy body.

3. The large-tonnage pre-tensioning device suitable for a floating foundation anchoring system according to claim 1 is characterized in that: The pre-tensioning fin includes a chain stopper, a guide rail roller, a reinforced support plate and a longitudinal baffle. There are two longitudinal baffles, which are arranged opposite to each other. The guide rail ball is arranged horizontally between the two longitudinal baffles. The reinforced support plate is arranged on the top of the two longitudinal baffles. The chain stopper is fixed on the top of the reinforced support plate. The center of the reinforced support plate is opened, and the anchor chain passes through the center hole of the reinforced support plate and then passes through the chain stopper.

4. The large-tonnage pre-tensioning device suitable for a floating foundation anchoring system according to claim 3 is characterized in that: At least one hole is formed on the longitudinal baffle to reduce the deadweight of the longitudinal baffle and to serve as an observation hole.

5. The large-tonnage pre-tensioning device suitable for a floating foundation anchoring system according to claim 4 is characterized in that: One side of the longitudinal baffle is fixed on the buoy body, and chamfers are provided at both upper and lower ends of the outer side to prevent scratches.

6. The large-tonnage pre-tensioning device suitable for a floating foundation anchoring system according to claim 3 is characterized in that: The chain stopper is a controllable one-way locking structure, which opens to allow the anchor chain to pass when the crane pulls the anchor chain upwards, and automatically locks the anchor chain under the action of gravity when the anchor chain is lowered.

7. The large-tonnage pre-tensioning device suitable for a floating foundation anchoring system according to claim 1, characterized in that: There are three pre-tensioning fins, and the angles between adjacent pre-tensioning fins are all 120°.

8. A method for using a large-tonnage pre-tensioning device suitable for a floating foundation anchoring system, characterized in that: The following steps are involved: (1) Use a construction vessel to transport the pre-tensioning device to the predetermined installation location, fix the pre-tensioning device on the stern side or the midship side, and align the cutting surface of the pre-tensioning device with the edge of the ship; (2) Use a 50T winch to pull the anchor chain through the chain stopper. The other end of the anchor chain is connected to the anchor. The winch first completes the initial pre-tensioning. Then use the crane to load the three anchor chains in the 120° direction to the designed tonnage step by step. At the same time, tighten the three anchor chains. After tightening, keep them stable for half an hour. Depending on the tightness of the anchor chains, control the crane to continue tightening the anchor chains. (3) After tightening the anchor chain, let it stand and confirm that the anchor chain and anchor have no displacement. Open the chain stopper to loosen the three anchor chains step by step until they reach 0 tonnage. Then put the anchor chains into the seabed one by one. At this time, the pre-tensioning of the anchor on the seabed has been completed. The pre-tensioning has the following effects: the pile anchor tension test has been completed, and the pile anchor chain has formed an arc under the mud; the high holding power anchor tension test has been completed; and the high-strength cable pre-tensioning has been completed; (4) The crane on the construction vessel hoists the anchor chain to the floating platform for offshore wind power installation, and then hoists the anchor chain back to the chain stopper on the floating platform for offshore wind power installation and passes it through the chain stopper before tightening the anchor chain. Repeat the above operation for the remaining anchor chains and tighten them in sequence; (5) After the construction is completed, the construction vessel carries the pre-tensioning device back to the next installation location.

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