Mooring system and method of designing the same

Abstract

This invention provides a mooring system and its design method. The mooring system is used to moor a platform, which includes four columns and a submerged body connected between adjacent columns. The mooring system includes four sets of connecting components connecting the platform, four piles that can be inserted into the water, and anchor chain components connecting the piles and connecting components. The connecting components include two connecting ropes connecting to a column and side ropes arranged on both sides of the connecting ropes. The connection points of the two connecting ropes to the same column are spaced apart. The side ropes are connected to the submerged bodies on both sides of the column, and each side rope is connected to the center of the length of the submerged body. The four piles are arranged at intervals, with opposite piles arranged diagonally, and the line connecting them passes through the center of the platform. Each anchor chain component includes two anchor chains and a connecting disc. The two anchor chains are respectively connected to two adjacent piles. The four connecting discs are respectively set corresponding to the four columns and located below the water surface. Each connecting disc connects the beam anchor chain and the two connecting ropes and the side ropes of a connecting component.

Description

Technical Field

[0001] This invention relates to the field of marine engineering equipment technology, and in particular to a mooring system and its design method. Background Technology

[0002] Currently, most floating structures are deployed in water depths of 50-80 meters. However, with the development of marine resources, the applications of semi-submersible floating platforms are becoming increasingly widespread. Due to cost constraints and the need to transport energy to land, the deployment locations of semi-submersible hydrogen production platforms are increasingly moving towards ultra-shallow water environments. Designing a mooring and positioning system with superior performance in harsh environments such as ultra-shallow water and extreme sea states has become an unavoidable challenge. Summary of the Invention

[0003] The purpose of this invention is to provide a mooring system and its design method for a mooring platform, which ensures the stability of the platform in shallow water conditions.

[0004] To solve the above-mentioned technical problems, the present invention provides a mooring system for mooring a platform. The platform is square and includes four columns and a lower floating body connected between two adjacent columns. The mooring system includes four sets of connecting components connecting the platform, four piles that can be inserted into the seabed, and an anchor chain assembly connecting the piles and the connecting components.

[0005] Each of the connecting components includes two connecting ropes connecting to one of the columns and side ropes arranged on both sides of the connecting ropes. The connection points of the two connecting ropes to the same column are spaced apart. The two side ropes are connected to the lower floats on both sides of the column in a one-to-one correspondence. Each side rope is connected to the center of the length of the lower float.

[0006] The four piles are arranged at intervals, with two opposite piles arranged diagonally, and the line connecting them passes through the center of the platform;

[0007] Each of the anchor chain assemblies includes two anchor chains and a connecting plate. The two anchor chains are respectively connected to two adjacent piles. The four connecting plates are respectively set for the four columns and located below the water surface. Each connecting plate connects the anchor chain and the two connecting ropes and two side ropes of the connecting assembly.

[0008] In one embodiment, the connecting rope and the side rope are made of lightweight, high-strength materials;

[0009] The connecting rope and the side rope are made of high molecular weight polyethylene (HMWPE) cables.

[0010] The connection point between the connecting rope and the column is higher than the connection point between the side rope and the lower float.

[0011] In one embodiment, the cross-section of the connecting disc is polygonal, and it is provided with at least six connecting holes. Two anchor chains belonging to the same anchor chain assembly are connected to two of the connecting holes respectively. The two connecting ropes and two side ropes of each connecting assembly are connected to four of the connecting holes respectively.

[0012] In one embodiment, the anchor chain assembly further includes connecting rings corresponding to the connecting holes, each connecting ring passing through the corresponding connecting hole for connecting other structural components;

[0013] The connecting plate is made of high-strength alloy.

[0014] In one embodiment, the anchor chain assembly further includes a connecting rod connected to the top of the connecting disc and a float located at the top of the connecting rod, the connecting rod being hinged to the connecting disc and the float floating on the water surface.

[0015] In one embodiment, a lug is fixed to the top of the connecting plate, the lug has a lug hole, and a transition ring is provided at the bottom of the connecting rod, the transition ring passing through the lug hole;

[0016] The upper surface of the ear plate is curved.

[0017] In one embodiment, a connecting chain is provided on the pile, and the anchor chain is connected to the connecting chain;

[0018] The anchor chain and the connecting chain are connected by a rope.

[0019] The present invention also provides a design method for the mooring system as described above, comprising the following steps:

[0020] Determine the environmental conditions of the water area where the platform is located, including wind, waves, current loads, and underwater geological conditions;

[0021] Determine the type, quantity, and placement of the connecting rope, the side rope, and the anchor chain;

[0022] Determine the properties and connection positions of the connecting rope, the side rope, and the anchor chain;

[0023] The mooring system was calculated in both the frequency and time domains using numerical simulation.

[0024] The calculation results are analyzed and compared with relevant standards. If the calculation results meet the standard requirements, then the design of the mooring system is reasonable.

[0025] In one embodiment, the environmental conditions include wind spectrum, wave spectrum and ocean current data, as well as marine geological data.

[0026] In one embodiment, the properties include length, diameter, dry weight, wet weight, axial stiffness, and breaking force.

[0027] As can be seen from the above technical solution, the advantages and positive effects of the present invention are as follows:

[0028] The mooring system of this invention includes a connecting assembly, an anchor chain assembly, and a pile. The above structure forms a star-shaped structure. It is connected to the platform through multiple connecting ropes and multiple side ropes, and then connected to the connecting disc through multiple connecting ropes and multiple side ropes. Finally, it is connected to the pile fixed to the seabed through the anchor chain, which increases the suspension length and restoring force of the anchor chain and increases stability.

[0029] The mooring system, through its multi-point connection with the platform, makes the platform more balanced in terms of force, improves the positioning function, and further enhances stability, ensuring that the platform can work stably under environmental loads such as wind, waves, and currents. Attached Figure Description

[0030] Figure 1 This is a top view schematic diagram of a mooring platform according to one embodiment of the mooring system of the present invention.

[0031] Figure 2 This is a partial structural diagram of a mooring platform of the mooring system of the present invention.

[0032] Figure 3 This is a structural schematic diagram of the connecting disc, connecting rod, and float of the present invention.

[0033] The annotations in the attached figures are explained as follows:

[0034] 11. Upright column; 12. Lower floating body;

[0035] 21. Connecting rope; 22. Side rope; 23. Guide cable; 24. Connecting disc; 25. Anchor chain; 26. Connecting ring; 271. Connecting rod; 272. Buoy; 273. Ear plate; 274. Transition ring; 28. Pile; 291. Connecting chain; 292. Rope. Detailed Implementation

[0036] Although the invention can be readily embodied in various forms, only some specific embodiments are shown in the accompanying drawings and will be described in detail in this specification. It is understood that this specification should be regarded as an exemplary illustration of the principles of the invention and is not intended to limit the invention to what is described herein.

[0037] Therefore, a feature pointed out in this specification is used to illustrate one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. While certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0038] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various elements of the invention are relative rather than absolute. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the descriptions of the positions of these elements change, these directional indications also change accordingly.

[0039] It should be noted that the design challenges of mooring systems in ultra-shallow water environments are as follows:

[0040] 1. In ultra-shallow water environments, the mooring system exhibits strong nonlinearity. The suspension section of the catenary mooring line is relatively short, which reduces the restoring force of the mooring line and leads to excessive platform motion response.

[0041] 2. At a water depth of 20m, the motion mechanism of the floating body is more complex, and more factors affect the mooring forces. Therefore, compared to deep water, the design of shallow water mooring systems is more difficult and the positioning capability is weaker, especially in extreme environments and under mooring failure conditions.

[0042] Therefore, this invention provides a mooring system for mooring platforms, which, through a novel structure, effectively ensures the stability of the platform in shallow water conditions. This mooring system is particularly suitable for ultra-shallow water environments.

[0043] The platform is square in shape and consists of four pillars and a lower floating body connecting adjacent pillars. This platform can be used to produce hydrogen.

[0044] Combination Figure 1 and Figure 2The mooring system includes four sets of connecting components for connecting the platform, four piles 28 that can be inserted into the water, and anchor chain assemblies connecting the piles 28 and the connecting components. Each connecting component includes two connecting ropes 21 connecting a column 11 and side ropes 22 arranged on both sides of the connecting ropes 21. The connection points of the two connecting ropes 21 to the same column 11 are spaced apart. The side ropes 22 are connected one-to-one to the lower floats 12 on both sides of the column 11, and each side rope 22 is connected to the center of the length of the lower float 12. The four piles 28 are arranged at intervals, with opposite piles 28 arranged diagonally, and the connecting line passes through the center of the platform. Each anchor chain assembly includes two anchor chains 25 and a connecting disc 24. The two anchor chains 25 are respectively connected to two adjacent piles 28. The four connecting discs 24 are respectively set for the four columns 11 and are located below the water surface. Each connecting disc 24 connects the beam anchor chain 25 and the two connecting ropes 21 and the side ropes 22 of a connecting component.

[0045] By connecting components, anchor chain components, and piles 28, a star-shaped structure is formed, providing the platform with stable positioning capabilities and ensuring stable operation of the platform under environmental loads such as wind, waves, and currents.

[0046] The following is a detailed description of the mooring system.

[0047] There are four sets of connecting components. Two connecting ropes 21 in each of the four sets of connecting components correspond to four columns 11, meaning that two connecting ropes 21 are connected to each column 11. The two side ropes 22 in each of the four sets of connecting components correspond to the centers of two lower floats 12, meaning that the center of each lower float 12 corresponds to two side ropes 22, and the two side ropes 22 belong to two different connecting components.

[0048] Specifically, the connection points of the two connecting ropes 21 in each set of connecting components and the same column 11 are spaced apart. The connection points are located on the outside of the column 11, where the outside is defined with reference to the platform's usage state, with the direction towards the center of the platform being considered inside, and vice versa.

[0049] The connection points of the connecting ropes 21 in the two sets of connecting components arranged diagonally are symmetrical about the center of the platform.

[0050] The two side ropes 22 in each connecting assembly are connected one-to-one with the lower floats 12 on both sides of the column 11, and the center of the length of each side rope 22 is connected to the lower float 12.

[0051] The connecting rope 21 and the side rope 22 are made of lightweight, high-strength materials, giving them not only high load-bearing capacity but also the ability to float on water. Specifically, the connecting rope 21 and the side rope 22 are made of high-molecular-weight polyethylene ropes, which are also wear-resistant and corrosion-resistant, making them suitable for complex environments such as the ocean.

[0052] The mooring system includes a cable guide 23 fixed to the platform, and the cable guide 23 has a cable guide hole.

[0053] The connecting rope 21 is threaded through the cable guide hole on the column 11 to connect with the column 11. The side rope 22 is threaded through the cable guide hole on the lower float 12 to connect with the lower float 12.

[0054] The cable guide component 23 may include a cable guide block with cable guide holes. The cable guide block is fixed to the column 11 for connection to the connecting rope 21, and when fixed to the lower float 12, it is connected to the side rope 22. Preferably, the cable guide component 23 also includes reinforcing blocks located at the upper and lower ends of the cable guide block. These reinforcing blocks are fixedly connected to the column 11 or to the lower float 12 to increase connection strength.

[0055] The connection point between the connecting rope 21 and the column 11 is higher than the connection point between the side rope 22 and the lower float 12. That is, the cable guide 23 set on the column 11 is higher than the cable guide 23 set on the lower float 12.

[0056] Furthermore, the cable guide 23 on the column 11 is located above the water surface.

[0057] The anchor chain assembly includes two anchor chains 25 and a connecting disc 24.

[0058] The cross-section of the connecting plate 24 is polygonal, and it has at least six connecting holes. One connecting component corresponds to one connecting plate 24. Therefore, the connecting plate 24 connects the two connecting ropes 21 and the two side ropes 22 of a set of connecting components. That is, the two connecting ropes 21 and the two side ropes 22 of each connecting component are connected to four connecting holes respectively.

[0059] The platform is formed into a cross-shaped structure by connecting components and connecting disc 24. Both the connecting rope 21 and the side rope 22 are made of soft materials, which gives them resilience, thus providing the platform with good resilience.

[0060] Two anchor chains 25 belonging to the same anchor chain assembly are connected to two corresponding connecting holes.

[0061] See Figure 3 The connecting plate 24 has a regular octagonal cross-section. Six connecting holes are respectively located at the six vertices of the connecting plate 24. In other embodiments, the connecting plate 24 can also have a circular or regular hexagonal cross-section. The connecting holes can be located at any position on the connecting plate 24 as needed.

[0062] The connecting plate 24 is made of a high-strength alloy. For example, it can be a copper alloy, a zinc alloy, or a cemented carbide. The copper alloy can be a Cu-15Ni-8Sn alloy, the zinc alloy can be a ZA303 alloy, and the cemented carbide can be KF10D (ultra-fine grain tungsten-cobalt alloy).

[0063] The anchor chain assembly also includes connecting rings 26 corresponding to the connecting holes. Each connecting ring 26 passes through the corresponding connecting hole and is used to connect other structural components. That is, the connecting rope 21 and the side rope 22 are both connected to the connecting disc 24 by connecting to the connecting ring 26, and the anchor chain 25 is connected to the connecting disc 24 by connecting to the connecting ring 26.

[0064] Because the connecting ring 26 can move within the connecting hole and is circular in shape, it ensures that the connecting angle of the connecting rope 21 connected to it is more selective, the connecting angle of the side rope 22 connected to it is more selective, and the connecting angle of the anchor chain 25 connected to it is more selective, and the connection is convenient.

[0065] Furthermore, a ring structure can be added between the connecting ring 26 and the anchor chain 25.

[0066] Continue reading Figure 3 The anchor chain assembly also includes a connecting rod 271 connected to the top of the connecting disc 24 and a float 272 located on top of the connecting rod 271. The connecting rod 271 is hinged to the connecting disc 24, and the float 272 floats on the water surface. The length of the connecting rod 271 can be adjusted according to actual conditions.

[0067] The pontoon 272 provides buoyancy to the side rope 22, connecting rope 21, and anchor chain 25 by providing buoyancy to the connecting plate 24. The pontoon 272 also serves to fix the anchor chain 25 in a certain position. That is, when the platform is moved, the connection between the side rope 22, connecting rope 21 and connecting plate 24 can be disconnected, leaving the anchor chain 25 and pontoon 272 in place. When the platform is back in position for operation, the side rope 22 and connecting rope 21 can be connected to the connecting plate 24.

[0068] Specifically, in this embodiment, a lug 273 is fixed to the top of the connecting plate 24, and a lug hole is provided on the lug 273. A transition ring 274 is provided at the bottom of the connecting rod 271, and the transition ring 274 passes through the lug hole to realize the hinged connection between the connecting rod 271 and the connecting plate 24. The upper surface of the lug 273 is preferably arc-shaped to facilitate the movement of the connecting rod 271 along the arc surface.

[0069] Four piles 28 are arranged at intervals, with two opposite piles 28 arranged diagonally, and the line connecting them passes through the center of the platform.

[0070] Each pile 28 is connected to one of the two anchor chains 25, meaning that the two anchor chains 25 share one pile 28, which saves a lot of construction time and economic costs.

[0071] A connecting chain 291 is installed on the pile 28, and an anchor chain 25 is connected to the connecting chain 291. The anchor chain 25 and the connecting chain 291 are specifically connected by a rope 292.

[0072] The pile 28, connecting chain 291, anchor chain 25, and connecting disc 24 are located below the water surface. The side rope 22 connects the lower float 12 and the connecting disc 24; therefore, the side rope 22 is also located below the water surface. One end of the connecting rope 21 is connected to the column 11, and the other end is connected to the connecting disc 24; therefore, the connecting rope 21 is partially above and partially below the water surface.

[0073] In the entire mooring system, the distance between the connecting plate 24 and the center of the platform is less than the distance between the pile 28 and the center of the platform, ensuring that the connecting rope 21 and the anchor chain 25 connect the platform and the pile 28, making the load distribution more reasonable.

[0074] The mooring system includes a connecting assembly, an anchor chain assembly, and a pile 28. The above structure forms a star-shaped structure. It is connected to the platform through multiple connecting ropes 21 and multiple side ropes 22, and then connected to the connecting disc 24. Finally, it is connected to the pile 28 fixed to the seabed through the anchor chain 25, which increases the suspension length and restoring force of the anchor chain 25 and increases stability.

[0075] The mooring system, through its multi-point connection with the platform, makes the platform more balanced in terms of force, improves the positioning function, and further enhances stability, ensuring that the platform can work stably under environmental loads such as wind, waves, and currents.

[0076] This application also provides a design method for the above-mentioned mooring system, comprising the following steps:

[0077] S1. Determine the environmental conditions of the waters where the platform is located, including wind, waves, current loads, and underwater geological conditions.

[0078] Specifically, environmental conditions include wind spectrum, wave spectrum, ocean current data, and marine geological data.

[0079] S2. Determine the type, quantity, and placement of the connecting rope 21, side rope 22, and anchor chain 25.

[0080] Among them, the type of anchor chain 25 refers to its grade, and the type of connecting rope 21 and side rope 22 refers to their specific materials.

[0081] For example, anchor chain 25 has grades R4, R3, R5, etc.

[0082] The connecting rope 21 and the side rope 22 are made of polyethylene. The connecting rope 21 and the side rope 22 can also be made of polyester or polypropylene.

[0083] There are 8 side ropes 22 and 8 connecting ropes 21, for a total of 16 ropes. Divide the ropes into 4 groups of 4 ropes each. There are 8 anchor chains 25, also divided into 4 groups of 2 ropes each.

[0084] The deployment is as follows: two connecting ropes 21 are connected to each column 11 of the platform, and two side ropes 22 are connected to the lower float 12 of the platform. The other ends of the connecting ropes 21 and the side ropes 22 are connected to the connecting discs 24. Two anchor chains 25 are connected to each connecting disc 24, and the anchor chains 25 are finally connected to the piles 28.

[0085] The two connecting ropes 21, the two side ropes 22 and the two anchor chains 25 connected to the same connecting plate 24 are grouped together. After determining the position of one group, the positions of the other groups are obtained.

[0086] In this embodiment, the platform has a square cross-section, the connecting plate 24 is located on the extension of the platform's diagonal, and each pile 28 is equidistant from the center of the platform.

[0087] S3. Determine the properties and connection positions of the connecting rope 21, side rope 22, and anchor chain 25.

[0088] Specifically, the properties include length, diameter, dry weight, wet weight, axial stiffness, and breaking force.

[0089] The connection location is set according to the description above.

[0090] S4. Use numerical simulation to perform frequency domain and time domain calculations on the mooring system.

[0091] Specifically, commercial software such as Sesam (Super Element Structure Analysis Module, a finite element analysis software developed by Det Norske Veritas) or OrcaFlex (a dynamic analysis software in the field of marine engineering) can be used to perform frequency domain and time domain calculations on the mooring system.

[0092] S5. Analyze the calculation results and compare them with relevant standards. If the calculation results meet the standard requirements, then the design of the mooring system is reasonable.

[0093] Specifically, the frequency domain and time domain calculation results are analyzed, mainly considering whether the tension of the cable, the pull-out force of the pile 28, the platform offset, and the fatigue of the mooring cable meet the specifications.

[0094] If the specifications are not met, adjust the data in steps S2-S3 until the specifications are met.

[0095] The standards mainly include the relevant requirements of classification societies such as Det Norske Veritas (DNV), American Bureau of Shipping (ABS), China Classification Society (CCS), and Bureau Veritas (BV).

[0096] For example, with a platform operating in water depth of 20m, the types and properties of the connecting rope 21, side rope 22 and anchor chain 25 are shown in Table 1, and the connection positions are shown in Table 2.

[0097] Table 1. Types and properties of connecting ropes, side ropes, and anchor chains.

[0098]

[0099]

[0100] Table 2. Connection positions of connecting ropes, side ropes, and anchor chains.

[0101]

[0102] Although the invention has been described with reference to several typical embodiments, it should be understood that the terminology used is illustrative and exemplary, and not restrictive. Since the invention can be embodied in many forms without departing from the spirit or essence of the invention, it should be understood that the above embodiments are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope defined by the appended claims. Therefore, all variations and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A mooring system for mooring a platform, said platform being square shaped comprising four columns and a lower buoy connected between two adjacent of said columns, characterized in that, The mooring system includes four sets of connecting components that connect the platform, four piles that can be inserted into the seabed, and four sets of anchor chain assemblies that connect the piles and the connecting components. Each of the connecting components includes two connecting ropes connecting to one of the columns and side ropes arranged on both sides of the connecting ropes. The connection points of the two connecting ropes to the same column are spaced apart. The two side ropes are connected to the lower floats on both sides of the column in a one-to-one correspondence. Each side rope is connected to the center of the length of the lower float. The four piles are arranged at intervals, with two opposite piles arranged diagonally, and the line connecting them passes through the center of the platform; Each of the anchor chain assemblies includes two anchor chains and a connecting plate. The two anchor chains are respectively connected to two adjacent piles. The four connecting plates are respectively set for the four columns and located below the water surface. Each connecting plate connects the two anchor chains in the anchor chain assembly and the two connecting ropes and two side ropes of the connecting assembly. Each pile is connected to one of two anchor chain assemblies, and the mooring system as a whole is star-shaped.

2. The mooring system according to claim 1, characterized in that, The connecting rope and the side rope are made of lightweight, high-strength materials; The connection point between the connecting rope and the column is higher than the connection point between the side rope and the lower float.

3. The mooring system according to claim 2, characterized in that, The connecting rope and the side rope are made of high molecular weight polyethylene (HMWPE) cables.

4. The mooring system according to claim 1, characterized in that, The cross-section of the connecting disc is polygonal, and it has at least six connecting holes. Two anchor chains belonging to the same anchor chain assembly are connected to two of the connecting holes respectively. The two connecting ropes and two side ropes of each connecting assembly are connected to four of the connecting holes respectively.

5. The mooring system according to claim 4, characterized in that, The anchor chain assembly also includes a connecting ring corresponding to the connecting hole, and each connecting ring passes through the corresponding connecting hole to connect the connecting rope, the side rope and the anchor chain; The connecting plate is made of high-strength alloy.

6. The mooring system according to claim 1, characterized in that, The anchor chain assembly also includes a connecting rod connected to the top of the connecting plate and a float located at the top of the connecting rod. The connecting rod is hinged to the connecting plate, and the float floats on the water surface.

7. The mooring system according to claim 6, characterized in that, The top of the connecting plate is fixed with an ear plate, the ear plate is provided with an ear hole, and the bottom of the connecting rod is provided with a transition ring, which passes through the ear hole; The upper surface of the ear plate is curved.

8. The mooring system according to claim 1, characterized in that, A connecting chain is provided on the pile, and the anchor chain is connected to the connecting chain. The anchor chain and the connecting chain are connected by a rope.

9. A design method for a mooring system as described in any one of claims 1-8, characterized in that, Includes the following steps: Determine the environmental conditions of the water area where the platform is located, including wind, waves, current loads, and underwater geological conditions; Determine the type, quantity, and placement of the connecting rope, the side rope, and the anchor chain; Determine the properties and connection positions of the connecting rope, the side rope, and the anchor chain; The mooring system was calculated in both the frequency and time domains using numerical simulation. The calculation results are analyzed and compared with relevant standards. If the calculation results meet the standard requirements, then the design of the mooring system is reasonable.

10. The design method according to claim 9, characterized in that, The environmental conditions include wind spectrum, wave spectrum, ocean current data, and marine geological data.

11. The design method according to claim 9, characterized in that, The properties include length, diameter, dry weight, wet weight, axial stiffness, and breaking force.

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