Multi-layer airbag system for auxiliary suction anchor installation and its usage method

Abstract

This invention relates to the field of marine engineering technology and discloses a multi-layer airbag system and its usage method for assisting in the installation and sinking of suction anchors. The system includes a suction anchor, an airbag assembly, a gas supply unit, a liquid supply unit, and a piping system. The suction anchor has a top cover with a drain outlet and a drain valve. The airbag assembly includes an outer airbag and an inner airbag located inside it. The gas supply unit is mounted on the suction anchor and includes a first gas storage device for storing working gas and a second gas storage device for storing protective gas. The liquid supply unit includes a freshwater storage bottle. The piping system connects the airbag assembly, the gas supply unit, and the liquid supply unit and is equipped with control valves. The inner airbag is connected to the first gas storage device and the freshwater storage bottle, and the outer airbag is connected to the second gas storage device. The outer airbag covers the inner airbag, forming an isolation barrier, thus solving the problem that suction anchor installation and sinking relies on high-performance submersible pump skid mounting.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, specifically to a multi-layer airbag system for assisting in the installation and sinking of suction anchors and its usage method. Background Technology

[0002] Suction anchors are a commonly used type of anchor in marine engineering, characterized by good load-bearing capacity, adaptability to deep seas, and recoverable anchor bodies. They are increasingly used in both fixed and floating offshore platforms. Suction anchors typically require a submersible pump skid for pumping or filling the anchor body.

[0003] There are some technical drawbacks to the installation and retrieval of submersible pump skids for suction anchors. Before sinking the suction anchor, the submersible pump skid needs to be installed on it. After sinking, the skid needs to be removed underwater, involving underwater operations and posing a certain challenge. The submersible pump skid for suction anchors requires good watertightness, high pressure resistance, and corrosion resistance, placing high demands on the equipment's performance. Furthermore, the submersible pump skid typically requires significant power from the mother vessel via umbilical cables, making the propulsion system quite complex. Summary of the Invention

[0004] In view of this, the present invention provides a multi-layer airbag system and method for assisting in the installation and sinking of suction anchors, so as to solve the problem that suction anchors require the use of submersible pump skid mounting and a supporting complex power system.

[0005] In a first aspect, the present invention provides a multi-layer airbag system for assisting in the installation and sinking of suction anchors, comprising:

[0006] A suction anchor, with a suction anchor top cover, and a drain outlet and a drain valve on the suction anchor top cover;

[0007] An airbag assembly is disposed inside the suction anchor; the airbag assembly includes an outer airbag and an inner airbag located inside it;

[0008] A gas supply unit is installed on the suction anchor; the gas supply unit includes a first gas storage device for storing working gas and a second gas storage device for storing protective gas.

[0009] Liquid supply unit, including freshwater storage tank;

[0010] A piping system connects the airbag assembly, the gas supply unit, and the liquid supply unit, and is equipped with control valves;

[0011] The inner airbag is connected to the first gas storage device and the fresh water storage bottle, the outer airbag is connected to the second gas storage device, and the outer airbag covers the outside of the inner airbag to form an isolation barrier.

[0012] During operation, the suction anchor is lowered to the predetermined position on the seabed, and the drain valve is opened. It sinks under its own weight, with the cylinder penetrating the seabed to the predetermined depth. The valve of the second gas storage device is opened, injecting a small amount of protective gas into the isolation chamber to the predetermined pressure, forming a gas barrier to prevent leakage of working gas should the inner airbag rupture later. The valve of the first gas storage device is opened, and high-pressure working gas is injected into the inner airbag; the expansion of the inner airbag pushes the expansion of the outer airbag, jointly compressing the seawater in the chamber, which is then quickly discharged through the drain outlet. The working gas valve and drain valve are closed, and fresh water is injected into the inner airbag in 3-5 stages, while simultaneously monitoring the air pressure data; the working gas dissolves rapidly upon contact with water, reducing the air pressure inside the airbag, causing the airbag to contract and creating a pressure difference between the inside and outside of the suction anchor; after the dissolution releases heat, the residual gas inside the inner airbag cools and contracts, further reducing the air pressure inside the airbag and strengthening the aforementioned pressure difference; the pressure difference between the inside and outside of the suction anchor drives it to continue sinking until the designed penetration depth.

[0013] This structure allows for the installation, sinking, and jacking / retrieval of the suction anchor with minimal valve operations, requiring only a small amount of power for valve switching. It solves the problem of suction anchor installation relying on high-performance submersible pump skids, avoiding complex underwater operations such as the installation and disassembly of submersible pump skids and eliminating the need for a complex power system for the submersible pump. The inner air bladder maintains the pressure difference between the inside and outside of the suction anchor through a gas dissolution equilibrium effect, addressing the issue of pressure differential decreasing due to soil seepage after the submersible pump skid is removed. The protective gas must be able to neutralize the aqueous solution of the working gas. For example, if the working gas is ammonia, the protective gas is hydrogen chloride, and vice versa.

[0014] In one optional embodiment, the inner airbag includes at least one main inner airbag and one backup inner airbag, both of which are connected to the first gas storage device and the freshwater storage bottle.

[0015] The inner airbag employs a dual-unit redundant design, comprising at least one main inner airbag and one backup inner airbag. Both are independently connected to the first gas storage device and the freshwater storage bottle, and are controlled synchronously or independently via parallel pipelines. In the event of an accidental rupture of the main inner airbag or abnormal pressure, the working gas and freshwater pathways of the backup airbag can be opened by closing the main airbag pipeline valve, allowing it to continue performing the gas dissolution and pressure differential formation operations, ensuring uninterrupted suction anchor penetration. Under conditions of high penetration resistance, both the main and backup inner airbags can be opened simultaneously, injecting double the amount of working gas and freshwater to accelerate water discharge and reduce pressure within the cylinder, enhancing the pressure difference between the inside and outside of the suction anchor and improving penetration efficiency.

[0016] In one alternative embodiment, the inner wall of the suction anchor is partially or completely covered with a rubber anti-corrosion layer.

[0017] When partially covering the inner wall, cover the area where the airbag is installed and around the pipe interface. Cover the areas where the inner main airbag, inner backup airbag, and outer airbag contact the inner wall of the suction anchor to prevent the working gas from directly contacting the metal surface and causing corrosion if the airbag ruptures accidentally. At the interface where the pipe connecting the airbag and the storage bottle passes through the top cover of the suction anchor, cover a range extending outward from the interface for 200mm to prevent gas or liquid leaking from the pipe from corroding the inner wall of the top cover.

[0018] When the working gas is a highly corrosive gas or the suction anchor needs to be used for a long time in a seabed environment with high salinity and high sulfide content, a full inner wall coverage solution should be adopted.

[0019] The outer airbag's isolation chamber, combined with a rubber anti-corrosion layer, completely blocks the risk of corrosion from working gases to the anchor body and marine pollution.

[0020] In one optional implementation, the inner backup airbag has the same volume and connection method as the inner main airbag, forming a redundant backup structure.

[0021] The geometric volume of the inner backup airbag is exactly the same as that of the inner main airbag, and the specific volume is designed according to the diameter of the suction anchor cylinder and the sinking depth requirements. Both adopt a cylindrical airbag structure, and the axial length is preferably matched with the height of the suction anchor cylinder to ensure that the seawater inside the cylinder can be effectively displaced after inflation.

[0022] The inner backup airbag and the inner main airbag are each connected to the first gas storage device via independent pipelines. Each pipeline is equipped with a pneumatic ball valve, which can be independently controlled by the construction vessel via a wired signal. The two pipelines converge at the outlet of the storage cylinder to form a main pipeline, ensuring that high-pressure gas can be injected into either airbag simultaneously or individually. The backup airbag and the main airbag are each connected to a freshwater storage cylinder via pipelines. One-way check valves are installed on the pipelines to prevent freshwater backflow, and flow regulating valves are installed at the outlets of the storage cylinders on both pipelines to control the freshwater injection rate synchronously or differentially according to the status of the airbags.

[0023] In one alternative embodiment, the piping system is made of acid and alkali resistant materials.

[0024] In one alternative embodiment, the multi-layer airbag system for assisting in the installation of the suction anchor further includes a mooring assembly comprising a marine eyeplate and an anchor chain disposed on the outer wall of the suction anchor.

[0025] In one alternative embodiment, the multi-layered airbag system for assisting the suction anchor installation further includes auxiliary components, such as lugs and sacrificial anodes connected to the outer wall of the suction anchor.

[0026] Secondly, the present invention also provides a method for using a multi-layer airbag system with auxiliary suction anchor installation, comprising the following steps:

[0027] Position the suction anchor to the seabed installation location, open the drainage valve, and let the suction anchor sink to the bottom of the cylinder and form a seal at the bottom by its own weight.

[0028] Inject protective gas between the outer and inner airbags;

[0029] Injecting working gas into the inner airbag causes the inner and outer airbags to expand, pushing seawater out through the drain outlet;

[0030] Close the drain valve and the working gas supply, inject fresh water into the inner air bladder to dissolve the working gas in the water, and the inner air bladder contracts to form a pressure difference between the inside and outside of the suction anchor, driving the suction anchor to sink.

[0031] The cooling and contraction effect after the working gas dissolves and releases heat enhances the pressure difference between the inside and outside of the suction anchor.

[0032] In one optional embodiment, during the steps of closing the drain valve and the working gas supply, injecting fresh water into the inner airbag to dissolve the working gas in the water, reducing the air pressure inside the inner airbag, and causing the airbag to contract to form a pressure difference between the inside and outside of the suction anchor, thereby driving the suction anchor to sink, the fresh water injection operation is performed multiple times, and the air pressure of the inner airbag is monitored in real time to control the injection amount.

[0033] In an optional implementation, the suction anchor retrieval step is also included:

[0034] Close the drain valve and inject a large amount of protective gas into the outer airbag to push the top cover of the suction anchor and the water inside the cylinder upward, thereby lifting the suction anchor away from the seabed. Attached Figure Description

[0035] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a multi-layer airbag system for assisting in the installation and sinking of a suction anchor according to an embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Seabed;

[0039] 2. Suction anchor; 21. Suction anchor top cover; 22. Drain outlet; 23. Rubber anti-corrosion layer;

[0040] 3. Outer airbag; 31. Inner main airbag; 32. Inner reserve airbag;

[0041] 41. First gas storage device; 42. Fresh water storage bottle; 43. Second gas storage device; 44. Piping system;

[0042] 91. Seabed surface; 96. Sacrificial anode; 97. Lifting lug; 98. Anchor chain; 99. Marine eyeplate. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Suction anchors are a commonly used type of anchor in marine engineering, characterized by good load-bearing capacity, adaptability to deep seas, and recoverable anchor bodies. They are increasingly used in both fixed and floating offshore platforms. Suction anchors typically require a submersible pump skid for pumping or filling the anchor body.

[0045] There are some technical drawbacks to the installation and retrieval of submersible pump skids for suction anchors. Before sinking the suction anchor, the submersible pump skid needs to be installed on it. After sinking, the skid needs to be removed underwater, involving underwater operations and posing a certain challenge. The submersible pump skid for suction anchors requires good watertightness, high pressure resistance, and corrosion resistance, placing high demands on the equipment's performance. Furthermore, the submersible pump skid typically requires significant power from the mother vessel via umbilical cables, making the propulsion system quite complex.

[0046] The following is combined with Figure 1 The following describes embodiments of the present invention.

[0047] According to an embodiment of the present invention, a multi-layer airbag system for assisting in the installation and sinking of a suction anchor is provided, comprising a suction anchor 2, an airbag assembly, a gas supply unit, a liquid supply unit, and a piping system 44. The suction anchor 2 has a suction anchor top cover 21, which has a drain outlet 22 and a drain valve. The airbag assembly is disposed inside the suction anchor 2. The airbag assembly includes an outer airbag 3 and an inner airbag located inside it. The gas supply unit is disposed on the suction anchor 2. The gas supply unit includes a first gas storage device 41 for storing working gas and a second gas storage device 43 for storing protective gas. The liquid supply unit includes a fresh water storage bottle 42. The piping system 44 connects the airbag assembly, the gas supply unit, and the liquid supply unit, and is provided with control valves. The inner airbag is connected to the first gas storage device 41 and the fresh water storage bottle 42, and the outer airbag 3 is connected to the second gas storage device 43, with the outer airbag 3 covering the outer part of the inner airbag to form an isolation barrier.

[0048] like Figure 1 As shown, the suction anchor 2 adopts a cylindrical steel structure, with an opening at the lower end that inserts into the seabed 1, and a sealed suction anchor top cover 21 welded to the top. A drain outlet 22 is provided on the top cover, equipped with a high-pressure sealing valve to control seawater discharge. The outer airbag 3 can be made of weather-resistant rubber and covers the entire inner airbag, forming an isolation cavity between the outer and inner airbags for filling with protective gas. The first gas storage device 41 stores high-pressure working gas (e.g., ammonia) and is connected to the inner airbag via a pipeline system 44. The second gas storage device 43 can store hydrogen chloride as a protective gas and is connected to the outer airbag 3 via the pipeline system 44. All valves in the pipeline system 44 are electric ball valves, remotely controlled by the construction vessel via cable. An integrated pressure sensor is located inside the inner airbag, and data is transmitted in real time to the monitoring terminal on the construction vessel.

[0049] In the above embodiment, during operation, the suction anchor 2 is lowered to a predetermined position on the seabed 1, and the drain valve is opened. It sinks under its own weight, and after the cylinder penetrates the seabed 1 to a predetermined depth, a soil seal is formed at the lower end. The valve of the second gas storage device 43 is opened, injecting protective gas (e.g., hydrogen chloride) into the isolation chamber to a predetermined pressure, forming a gas barrier to prevent leakage of working gas should the inner airbag rupture later. The valve of the first gas storage device is opened, and high-pressure working gas (e.g., ammonia) is injected into the inner airbag; the expansion of the inner airbag pushes the expansion of the outer airbag 3, jointly squeezing the seawater in the chamber, which is then quickly discharged through the drain outlet 22. The working gas valve and the drain valve are closed, and fresh water is injected into the inner airbag in 3-5 stages, while simultaneously monitoring the air pressure data; the working gas dissolves rapidly upon contact with water, reducing the air pressure inside the airbag, causing the airbag to contract and creating a pressure difference between the inside and outside of the suction anchor; after the heat is released during dissolution, the residual gas inside the inner airbag cools and contracts, further increasing the pressure difference between the inside and outside of the suction anchor; the pressure difference drives the suction anchor 2 to continue sinking until the designed penetration depth.

[0050] In this structure, the installation, sinking, and jacking / retrieval of the suction anchor 2 can be achieved with fewer valve operations, requiring only a small amount of power for valve opening and closing. This solves the problem that the installation and sinking of the suction anchor 2 relies on a high-performance submersible pump skid, avoiding complex underwater operations such as the installation and disassembly of the submersible pump skid, and eliminating the need for a complex power system for the submersible pump. The inner air bladder maintains the pressure difference between the inside and outside of the suction anchor 2 under the gas dissolution equilibrium effect, which solves the problem of the pressure difference between the inside and outside of the suction anchor 2 cylinder decreasing with soil seepage after the submersible pump skid is removed.

[0051] In one embodiment, the inner airbag includes at least one inner main airbag 31 and one inner backup airbag 32, both of which are connected to the first gas storage device 41 and the fresh water storage bottle 42.

[0052] In the above embodiments, the inner airbag adopts a dual-unit redundant design, including at least one inner main airbag 31 and one inner backup airbag 32. Both are independently connected to the first gas storage device 41 and the fresh water storage bottle 42, and are controlled synchronously or independently through parallel pipelines. When the inner main airbag 31 ruptures unexpectedly or the gas pressure is abnormal, the working gas and fresh water passages of the backup airbag can be opened by closing the main airbag pipeline valve, so that the backup airbag can continue to perform the gas dissolution and pressure difference formation operations, ensuring that the sinking process of the suction anchor 2 is not interrupted. Under the condition of high sinking resistance, the inner main airbag 31 and the inner backup airbag 32 can be opened simultaneously. By injecting double the working gas and fresh water, the water in the cylinder is discharged and the gas pressure is reduced, which enhances the pressure difference between the inside and outside of the suction anchor 2 and improves the sinking efficiency.

[0053] In operation, after the inner main airbag 31 is injected with working gas and then drained, if the pressure difference does not reach the expected level due to insufficient gas dissolution efficiency, the inner backup airbag 32 can be activated to simultaneously inject fresh water. This increases the amount of gas dissolved, further reducing the pressure inside the suction anchor cylinder. The exothermic effect of gas dissolution, followed by cooling by the surrounding seawater, causes both airbags to contract synchronously, enhancing the pressure difference and aiding in sinking. The backup airbag provides the system with fault tolerance, preventing installation interruptions due to the failure of a single airbag, making it particularly suitable for unmanned construction in deep-water environments. Furthermore, the dual-airbag design allows for flexible adjustment of the inflation volume based on the hardness of the seabed soil, enhancing the device's adaptability to different working conditions.

[0054] In other embodiments, the inner airbag can be equipped with multiple backup airbags (e.g., 2-3) to further improve system redundancy; or a modular design can be adopted so that the backup airbags can be activated in stages according to the penetration depth requirements, optimizing the consumption of gas and fresh water.

[0055] In one embodiment, the inner wall of the suction anchor 2 is partially or completely covered with a rubber anti-corrosion layer 23.

[0056] Depending on the corrosion risk level, the inner wall of the suction anchor 2 is partially or completely covered with a rubber anti-corrosion layer 23. Preferably, this anti-corrosion layer is made of neoprene rubber or EPDM rubber, with a thickness of 3-5 mm, and is tightly bonded to the metal surface of the inner wall of the suction anchor 2 through a vulcanization process. Furthermore, nano-level zinc oxide and graphene reinforcing agents are added to the rubber layer to improve its resistance to seawater corrosion, gas penetration, and wear resistance, while also possessing a temperature adaptability range of -40℃ to 120℃, meeting the long-term use requirements in deep sea and different water temperature environments.

[0057] When partially covering the inner wall, the area where the airbag is installed and around the pipe interface are covered. The areas where the inner main airbag 31, the inner spare airbag 32, and the outer airbag 3 contact the inner wall of the suction anchor 2 are covered to prevent the working gas from directly contacting the metal surface and causing corrosion after the airbag is accidentally ruptured. The pipe connecting the airbag and the storage bottle passes through the interface of the suction anchor top cover 21, and the coverage extends 200mm outward from the interface to prevent gas or liquid leaking from the pipe from corroding the inner wall of the top cover.

[0058] When the working gas is a highly corrosive gas or the suction anchor 2 needs to be used for a long time in the seabed environment with high salinity and high sulfide content, the inner wall full coverage solution shall be adopted.

[0059] In the above embodiment, the isolation cavity of the outer airbag 3 plus the rubber anti-corrosion layer completely blocks the corrosion of the anchor body by the working gas and the risk of marine pollution.

[0060] In one embodiment, the volume and connection method of the inner backup airbag 32 are the same as those of the inner main airbag 31, forming a redundant backup structure.

[0061] The geometric volume of the inner backup airbag 32 is exactly the same as that of the inner main airbag 31, and the specific volume is designed according to the diameter of the suction anchor 2 cylinder and the sinking depth requirements. Both adopt a cylindrical airbag structure, and the axial length is preferably matched with the height of the suction anchor 2 cylinder to ensure that the seawater inside the cylinder can be effectively displaced after inflation.

[0062] The inner backup airbag 32 and the inner main airbag 31 are each connected to the working gas storage cylinder 41 via independent pipes. Each pipe is equipped with a pneumatic ball valve, which can be independently controlled by the construction vessel via a wired signal. The two pipes converge at the cylinder outlet to form a main pipe, ensuring that high-pressure gas can be injected into either airbag simultaneously or individually. The backup airbag and the main airbag are each connected to the freshwater storage cylinder 42 via pipes. One-way check valves are installed on the pipes to prevent freshwater backflow, and both pipes are equipped with flow regulating valves at the cylinder outlets to control the freshwater injection volume synchronously or differentially according to the airbag status.

[0063] When the inner main airbag 31 ruptures due to scraping by rocks on the seabed 1 or gas corrosion, the system switches to the backup airbag through the following steps:

[0064] The construction vessel remotely shuts off the working gas pipeline ball valve and fresh water pipeline valve of the inner main airbag 31.

[0065] Open the working gas pipeline ball valve of the inner backup airbag 32 to inject high-pressure gas and displace the seawater in the cylinder;

[0066] After closing the drain outlet valve 22, open the freshwater pipe valve of the backup airbag. The pressure difference between the inside and outside of the suction anchor is formed by gas dissolution, which maintains the sinking process of the suction anchor 2.

[0067] In hard seabed 1 or deep-penetration conditions, the inner main airbag 31 and the inner backup airbag 32 can be activated simultaneously:

[0068] Simultaneously inject double the working gas to expand the total volume of the airbag to twice that of a single airbag, accelerating the discharge of seawater from the cylinder through the drain outlet 22;

[0069] By injecting fresh water in stages, the gas dissolution effect of the double airbags reduces the pressure inside the cylinder and increases the rate of penetration, thereby enhancing the driving force of the sinking.

[0070] In one embodiment, the piping system 44 is made of a material resistant to acid and alkali corrosion.

[0071] In a conventional seawater environment, the piping system 44 can be made of stainless steel pipes, which is suitable for working conditions where the working gas is ammonia.

[0072] In highly corrosive environments: When the working gas is hydrogen chloride and the seabed contains high concentrations of sulfides, titanium alloy pipes or composite pipes lined with glass fiber reinforced plastic should be selected.

[0073] In one embodiment, the multi-layer airbag system for assisting the suction anchor 2 in installation also includes a mooring assembly, which includes a marine eyeplate 99 and an anchor chain 98 disposed on the outer wall of the suction anchor 2.

[0074] The marine eye plate 99 is a circular or elliptical plate structure with a thickness of 20mm-30mm. Mooring holes are opened on the plate surface. The marine eye plate 99 is equipped with a suction anchor 2 on the outside of the cylinder. One end of the anchor chain 98 is connected to the mooring hole of the marine eye plate 99 through a shackle, and the other end is connected to the mooring pile or floating body of the offshore platform.

[0075] During the process of lowering the suction anchor 2 to the seabed 1, the levelness of the suction anchor 2 is adjusted in real time.

[0076] When it is necessary to retrieve the suction anchor 2, the mooring assembly and the outer airbag 3 work together:

[0077] Lifting Assist: The outer airbag 3 is injected with protective gas to lift the suction anchor 2;

[0078] In one embodiment, the multi-layered airbag system for the auxiliary suction anchor 2 installation also includes auxiliary components, including lugs 97 and sacrificial anodes 96 connected to the outer wall of the suction anchor 2.

[0079] Two to four lifting lugs 97 are evenly arranged around the circumference of the suction anchor 2 cylinder to ensure the center of gravity is balanced during lifting and to adjust the levelness of the suction anchor 2 during sinking and jacking. The sacrificial anode 96 is an aluminum alloy sacrificial anode 96, used to protect the metal structure of the suction anchor 2 from seawater corrosion.

[0080] During the initial installation phase, the suction anchor 2 is vertically lowered to the seabed 1 by connecting the lifting lug 97 to the lifting device of the construction vessel. When retrieving the suction anchor 2, the lifting lug 97 serves as the main stress point, and the suction anchor 2 is lifted from the seabed 1 by the lifting device.

[0081] According to an embodiment of the present invention, in another aspect, a method for using a multi-layer airbag system with auxiliary suction anchor 2 for installation and sinking is also provided. The method for using a multi-layer airbag system with auxiliary suction anchor 2 for installation and sinking includes the following steps:

[0082] Position the suction anchor 2 to the installation location on the seabed 1, open the drainage valve, and let the suction anchor 2 sink down to the point where the cylinder is inserted into the seabed 1 to form a lower seal by its own weight;

[0083] Inject protective gas between the outer airbag 3 and the inner airbag;

[0084] Inject working gas into the inner airbag to inflate the inner and outer airbags 3, and push seawater out through the drain outlet 22;

[0085] Close the drain valve and the working gas supply, inject fresh water into the inner air bladder to dissolve the working gas in the water, and the inner air bladder contracts to form a pressure difference between the inside and outside of the suction anchor 2, which drives the suction anchor 2 to sink.

[0086] The pressure difference between the inside and outside of the suction anchor 2 is enhanced by utilizing the heat released from the dissolution of the working gas and the cooling and contraction effect of the surrounding seawater.

[0087] The protective gas must be chemically incompatible with the working gas to avoid mixing and reaction. Injecting the protective gas forms a buffer layer, preventing working gas leakage into seawater in the event of accidental rupture of the inner airbag, thus reducing the risk of environmental pollution. During working gas injection, the airbag expansion pressure must exceed the hydrostatic pressure of the seawater to ensure effective drainage. The outer airbag 3 expands synchronously, its outer wall contacting the rubber anti-corrosion layer 23 of the inner wall of the suction anchor 2 to prevent frictional damage to the airbag. During the dissolution process, the airbag contraction rate is positively correlated with the freshwater injection volume; the injection rhythm needs to be adjusted according to the sinking resistance.

[0088] By employing a multi-layered airbag system that utilizes gas dissolution to achieve the installation and sinking of the suction anchor 2, the installation, sinking, and jacking / retrieval of the suction anchor 2 can be accomplished with fewer valve operations, requiring only a small amount of power for valve opening and closing. This solves the problem of the suction anchor 2 installation and sinking relying on a high-performance submersible pump skid, avoiding complex underwater operations such as the installation and disassembly of the submersible pump skid, and eliminating the need for a complex power system for the submersible pump. The inner airbag maintains the pressure difference between the inside and outside of the suction anchor 2 under the gas dissolution equilibrium effect, which solves the problem of the pressure difference between the inside and outside of the suction anchor 2 cylinder decreasing with soil seepage after the submersible pump skid is removed.

[0089] In one embodiment, during the steps of closing the drain valve and the working gas supply, injecting fresh water into the inner airbag to dissolve the working gas in the water, reducing the air pressure inside the inner airbag, and causing the airbag to contract to form a pressure difference between the inside and outside of the suction anchor, thereby driving the suction anchor 2 to sink, the fresh water injection operation is performed multiple times, and the air pressure of the inner airbag is monitored in real time to control the injection amount.

[0090] For example, freshwater injection is carried out in 3-5 stages, with the amount injected each time adjusted according to the volume of the inner airbag.

[0091] The injection interval is set based on the dissolution kinetics of the working gas to ensure that the fresh water and gas injected in the previous injection are fully dissolved.

[0092] In one embodiment, a suction anchor 2 recovery step is also included:

[0093] Close the drain valve and inject a large amount of protective gas into the outer airbag 3, which pushes the suction anchor top cover 21 and the water inside the cylinder to move upward, lifting the suction anchor 2 away from the seabed 1.

[0094] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A multi-layer airbag system for assisting suction anchor installation and sinking, characterized in that, include: A suction anchor (2) is provided with a suction anchor top cover (21) on its top, and the suction anchor top cover (21) is provided with a drain outlet (22) and a drain valve; An airbag assembly is disposed inside the suction anchor (2); the airbag assembly includes an outer airbag (3) and an inner airbag located inside it; A gas supply unit is provided on the suction anchor (2); the gas supply unit includes a first gas storage device (41) for storing working gas and a second gas storage device (43) for storing protective gas; The liquid supply unit includes a fresh water storage bottle (42); A pipeline system (44) is provided, connecting the airbag assembly, the gas supply unit and the liquid supply unit, and is equipped with control valves; The inner airbag is connected to the first gas storage device (41) and the fresh water storage bottle (42), the outer airbag (3) is connected to the second gas storage device (43), and the outer airbag (3) covers the outside of the inner airbag to form an isolation barrier.

2. The multi-layer airbag system for auxiliary suction anchor installation and sinking as described in claim 1, characterized in that, The inner airbag includes at least one inner main airbag (31) and one inner backup airbag (32), and both the inner main airbag (31) and the inner backup airbag (32) are connected to the first gas storage device (41) and the fresh water storage bottle (42).

3. The multi-layer airbag system for auxiliary suction anchor installation and sinking as described in claim 1 or 2, characterized in that, The inner wall of the suction anchor (2) is partially or completely covered with a rubber anti-corrosion layer (23).

4. The multi-layer airbag system for auxiliary suction anchor installation and sinking as described in claim 2, characterized in that, The inner backup airbag (32) has the same volume and connection method as the inner main airbag (31), forming a redundant backup structure.

5. The multi-layer airbag system for auxiliary suction anchor installation and sinking according to claim 1 or 2, characterized in that, The piping system (44) is made of acid and alkali resistant materials.

6. The multi-layer airbag system for auxiliary suction anchor installation and sinking according to claim 1 or 2, characterized in that, It also includes a mooring assembly, which includes a marine eyeplate (99) and an anchor chain (98) disposed on the outer wall of the suction anchor (2).

7. The multi-layer airbag system for auxiliary suction anchor installation and sinking according to claim 1 or 2, characterized in that, It also includes auxiliary components, which include lugs (97) and sacrificial anodes (96) connected to the outer wall of the suction anchor (2).

8. A method of using a multi-layer airbag system for assisting suction anchor installation and sinking, characterized in that, The multi-layer airbag system for sinking penetration, using the auxiliary suction anchor as described in any one of claims 1-7, includes the following steps: Position the suction anchor (2) to the installation position on the seabed (1), open the drainage valve, and let the suction anchor (2) sink down to the bottom of the cylinder when it is inserted into the seabed (1) to form a seal at the bottom. Inject protective gas between the outer airbag (3) and the inner airbag; Inject working gas into the inner airbag to inflate the inner and outer airbags and push seawater out through the drain outlet (22); Close the drain valve and the working gas supply, inject fresh water into the inner air bladder to dissolve the working gas in the water, and the inner air bladder contracts to form a pressure difference between the inside and outside of the suction anchor, driving the suction anchor (2) to sink. The pressure difference between the inside and outside of the suction anchor (2) is enhanced by utilizing the heat release from the dissolution of the working gas and the cooling and contraction effect of the surrounding seawater.

9. The method of using the multi-layer airbag system for auxiliary suction anchor installation and sinking as described in claim 8, characterized in that, When the drain valve and working gas supply are closed, fresh water is injected into the inner airbag to dissolve the working gas in the water. The air pressure inside the inner airbag decreases, and the airbag contracts to form a pressure difference between the inside and outside of the suction anchor, driving the suction anchor (2) to sink. In the process, the operation of injecting fresh water is carried out in multiple steps, and the air pressure of the inner airbag is monitored in real time to control the injection amount.

10. The method of using the multi-layer airbag system for auxiliary suction anchor installation and sinking as described in claim 8, characterized in that, It also includes the retrieval step of the suction anchor (2): Close the drain valve and inject a large amount of protective gas into the outer airbag (3) to push the suction anchor top cover (21) and the water in the cylinder to move upward, and lift the suction anchor (2) away from the seabed (1).

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