A temporary mooring positioning system suitable for FLNG tail transportation operation and its operation method

Abstract

The present invention discloses a temporary mooring positioning device suitable for FLNG tail transportation operation and an operation method thereof, belonging to the technical field of marine engineering, comprising a buoy, two sides of the buoy are respectively hinged with connecting beams, one end of the connecting beam on one side away from the buoy is hinged with the FLNG, and the other end of the connecting beam on the other side away from the buoy is hinged with a contact mechanism, an electric anchor windlass is fixed on the buoy, and the electric anchor windlass and the contact mechanism are connected to each other through a recovery cable. The present invention has the effect of effectively controlling the wave frequency motion of the hull.

Description

Technical Field

[0001] The present invention relates to the technical field of marine engineering, and in particular to a temporary mooring positioning system suitable for FLNG tail transportation operation and an operation method thereof. Background Art

[0002] FLNG (FPSO-LNG, floating liquefied natural gas production storage and unloading unit / ship) is an important engineering equipment for the development of marine natural gas resources. Due to its limited storage capacity, FLNG must be exported after a period of time to free up storage capacity for continued production. At present, the FLNG export system is mainly divided into two categories, the side by side offloading system and the tandem offloading system. Among them, the tandem offloading system is considered to be able to be used in more severe sea conditions and has a wider application prospect.

[0003] Currently, companies such as FMC and Technip have developed FLNG tail transfer systems. Their common feature is that they have high restrictions on the relative horizontal movement between the two ships. For example, the ATOL system developed by FMC requires that the relative movement of the two ends of the external transfer arm is within ±10m before external transfer operations can be carried out, and the ALLS system developed by Technip also requires relative movement of ±10m. Since the mooring system mainly controls the low-frequency movement of the floating body, and the movement in the above range is mainly controlled by the wave frequency, it is difficult to effectively control the movement of the two ships using conventional mooring cables. Therefore, the industry generally believes that the use of FLNG tail transfer technology must be equipped with a dynamically positioned LNG (liquefied natural gas carrier) transport ship.

[0004] In view of the above-mentioned related technologies, the applicant found that compared with conventional LNG carriers, dynamically positioned LNG carriers have higher costs and smaller tank capacity. Conventional mooring cables cannot provide sufficient restoring stiffness, resulting in a large range of motion of the two hulls, affecting the normal operation of external transmission. Therefore, the industry needs to propose a positioning system that can effectively control the wave frequency motion of the hull, has strong environmental adaptability, is easy to maintain, and has a relatively low cost. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a temporary mooring positioning device suitable for FLNG tail transportation operation and an operation method thereof.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A temporary mooring positioning device for FLNG tail transportation operation comprises a buoy. Connecting beams are respectively hinged on both sides of the buoy. One end of the connecting beam on one side away from the buoy is hinged to the FLNG, and the other end of the connecting beam on the other side away from the buoy is hinged to a contact mechanism. An electric anchor windlass is fixed on the buoy, and the electric anchor windlass and the contact mechanism are connected to each other through a recovery cable.

[0008] Furthermore, a ballast tank is provided in the buoy, and the restoring stiffness is adjusted by adjusting the ballast amount in the ballast tank.

[0009] Furthermore, a ballast weight is provided at the bottom of the buoy.

[0010] Furthermore, the contact mechanism comprises an articulated joint.

[0011] Furthermore, a spherical joint is provided at the end of the articulated joint, and the spherical joint engages with a groove on the outer side of the bow of the LNG transport ship during external transmission.

[0012] Furthermore, a mooring cable is provided at the end of the spherical joint, and the mooring cable is connected to the deck anchor machine at the bow of the LNG carrier during external transmission.

[0013] Furthermore, the spherical joint is covered with a rubber sheath.

[0014] Furthermore, the rubber sheath and the ball joint are detachably connected.

[0015] Furthermore, a floating ball is provided at one end of the recovery cable away from the electric anchor windlass.

[0016] Furthermore, an operation method using a temporary mooring positioning device for FLNG tail-transportation operation is provided.

[0017] Step 1: During the export operation, the LNG carrier gradually approaches from the stern of the FLNG, the electric anchor winch gradually releases the recovery cable, the contact mechanism gradually sinks into the water, and the buoy gradually approaches the bow of the LNG carrier under the action of waves and currents;

[0018] Step 2: The LNG carrier recovers the buoy and connects the recovery cable to the mooring cable and deck windlass on the LNG carrier. The deck windlass tightens the mooring cable, allowing the LNG carrier to move closer to the stern of the FLNG until the contact mechanism engages with the groove on the outside of the bow of the LNG carrier.

[0019] Step 3: FLNG begins to be exported. During this process, the relative movement between the two hulls generates an inward squeezing or outward stretching force on the buoy, causing the buoy to rise and fall.

[0020] Step 4: After the external transmission operation is completed, the deck windlass on the LNG carrier gradually loosens the mooring rope, so that the contact mechanism is separated from the groove on the outer side of the bow of the LNG carrier and gradually moves away from the LNG carrier, until the mooring rope is basically no longer subjected to a large tensile force, and then the mooring rope on the LNG carrier is disconnected from the deck windlass;

[0021] Step 5: The electric anchor winch gradually tightens the recovery cable until the contact mechanism contacts the buoy, and the LNG tanker sails away, completing the export operation.

[0022] In summary, compared with the prior art, the above technical solution has the following beneficial effects:

[0023] (1) The difference between the buoyancy and gravity of the buoy is converted into the mooring restoring force, resulting in a larger mooring restoring stiffness. At the same time, the relative motion of the two ships is effectively controlled. The center of gravity of the buoy itself is always lower than the center of buoyancy, which improves the stability of the motion.

[0024] (2) The contact mechanism is easy to recycle, and the rubber sheath at its front end can be replaced regularly;

[0025] (3) The restoring stiffness can be adjusted by adjusting the ballast amount of the ballast tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the entire system in an embodiment of the present invention;

[0027] Figure 2 2 is a schematic front view of the initial position of the FLNG export arm when the export operation starts in an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of an LNG carrier approaching the stern of an FLNG and connecting a mooring cable in an embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the main view when external transmission starts in an embodiment of the present invention;

[0030] Figure 5 Schematic diagram of FLNG release connection mooring cable in an embodiment of the present invention;

[0031] Figure 6 It is a schematic diagram of the departure of an LNG transport ship in an embodiment of the present invention.

[0032] Explanation of the reference numerals: 1. articulated joint; 2. connecting beam; 3. ballast weight; 4. buoy; 5. electric anchor windlass; 6. recovery cable; 7. contact mechanism; 8. rubber sheath; 9. mooring rope; 10. deck anchor windlass. DETAILED DESCRIPTION

[0033] The following is combined with Figure 1-6The principles and features of the present invention are described, and the examples given are only used to explain the present invention, rather than to limit the scope of the present invention.

[0034] The embodiment of the present invention discloses a temporary mooring positioning system suitable for FLNG tail transportation operation and an operation method thereof.

[0035] Reference Figure 1-Figure 6 A temporary mooring positioning device for FLNG tail transportation operation includes a buoy 4, which is a cylindrical steel structure with a diameter of 10 meters and a height of 50 meters. The two sides of the buoy 4 are respectively hinged with connecting beams 2, which are metal beams. There are four connecting beams 2, two of which form a group and are respectively located on both sides of the buoy 4. The two connecting beams 2 on one side are hinged to the FLNG at one end away from the buoy 4, and the two connecting beams 2 on the other side are hinged to a contact mechanism 7 at one end away from the buoy 4. The contact mechanism 7 is a junction plate. An electric anchor 5 is fixed on the buoy 4. The electric anchor 5 is located at the top of the buoy 4. The electric anchor 5 and the contact mechanism 7 are connected to each other through a recovery cable 6. The electric anchor 5 realizes the recovery or release of the contact mechanism 7 by tightening or loosening the recovery cable 6. A floating ball is provided at the end of the recovery cable 6 away from the electric anchor 5. The difference between the gravity and buoyancy of the buoy 4 is converted into a mooring restoring force, resulting in a larger mooring restoring stiffness. At the same time, the relative movement of the two ships is effectively controlled. The center of gravity of the buoy 4 itself is always lower than the center of buoyancy, which improves the stability of the movement.

[0036] A ballast tank is provided in the buoy 4, and the restoring stiffness is adjusted by adjusting the ballast amount in the ballast tank.

[0037] A ballast weight is provided at the bottom of the buoy 4 .

[0038] The contact mechanism 7 includes an articulated joint 1, and a spherical joint is provided at the end of the articulated joint 1. When the spherical joint is used for external transmission, it is engaged with a groove on the outer side of the bow of the LNG carrier. A mooring cable 9 is provided at the end of the spherical joint. When the spherical joint is used for external transmission, the mooring cable 9 is connected to the deck anchor windlass 10 of the bow of the LNG carrier. The anchor windlass of the deck completes the mooring connection and release between the FLNG and the LNG carrier by tightening or loosening the mooring cable 9.

[0039] The spherical joint is covered with a rubber sheath 8, which is detachably connected to the spherical joint and can be replaced regularly.

[0040] An operation method using a temporary mooring positioning device for FLNG tail transportation operation adopts the following technical solution:

[0041] Step 1: During the external transmission operation, the LNG carrier gradually approaches from the stern of the FLNG, the electric anchor windlass 5 gradually releases the recovery cable 6, the contact mechanism 7 gradually sinks into the water, and the buoy gradually approaches the bow of the LNG carrier under the action of waves and currents;

[0042] Step 2: The LNG carrier recovers the buoy, connects the recovery cable 6 to the mooring cable 9 and the deck windlass 10 on the LNG carrier, and the deck windlass 10 tightens the mooring cable 9, so that the LNG carrier moves further toward the tail of the FLNG until the contact mechanism 7 engages with the groove on the outer side of the bow of the LNG carrier;

[0043] Step 3: FLNG starts to export. During this process, the relative movement between the two hulls generates an inward squeezing or outward stretching force on the buoy 4, causing the buoy 4 to produce a heaving movement;

[0044] Step 4: After the external transmission operation is completed, the deck windlass 10 on the LNG carrier gradually loosens the mooring rope 9, so that the contact mechanism 7 is separated from the groove on the outer side of the bow of the LNG carrier and gradually moves away from the LNG carrier, until the mooring rope 9 is basically no longer subjected to a large tensile force, and then the mooring rope 9 on the LNG carrier is disconnected from the deck windlass 10;

[0045] Step 5: The electric anchor windlass 5 gradually tightens the recovery cable 6 until the contact mechanism 7 contacts the buoy 4, and the LNG transport ship sails away, completing the export operation.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An operating method of a temporary mooring positioning device for FLNG tail transportation operation, characterized in that: The buoy (4) comprises a buoy (4), wherein connecting beams (2) are respectively hingedly connected on both sides of the buoy (4), wherein one end of the connecting beam (2) on one side away from the buoy (4) is hingedly connected to the FLNG, and the other end of the connecting beam (2) on the other side away from the buoy (4) is hingedly connected to a contact mechanism (7), an electric anchor windlass (5) is fixedly arranged on the buoy (4), the electric anchor windlass (5) and the contact mechanism (7) are connected to each other via a recovery cable (6), and a floating ball is arranged on the end of the recovery cable (6) away from the electric anchor windlass (5); The method of action also includes the following steps: Step 1: During the export operation, the LNG carrier gradually approaches from the stern of the FLNG, the electric anchor windlass (5) gradually releases the recovery cable (6), the contact mechanism (7) gradually sinks into the water, and the buoy gradually approaches the bow of the LNG carrier under the action of waves and currents; Step 2: The LNG carrier recovers the buoy, connects the recovery cable (6) to the mooring cable and deck windlass (10) on the LNG carrier, and the deck windlass (10) tightens the mooring cable (9) so that the LNG carrier moves closer to the stern of the FLNG until the contact mechanism (7) engages with the groove on the outer side of the bow of the LNG carrier; Step 3: The FLNG starts to be transported out. During the process, the relative movement between the two hulls generates an inward squeezing or outward stretching force on the buoy (4), causing the buoy (4) to produce a heaving movement; Step 4: After the external transmission operation is completed, the deck windlass (10) on the LNG carrier gradually loosens the mooring rope (9), so that the contact mechanism (7) is separated from the groove on the outer side of the bow of the LNG carrier and gradually moves away from the LNG carrier, until the mooring rope (9) is basically no longer subjected to a large tensile force, and then the mooring rope (9) on the LNG carrier is disconnected from the deck windlass (10); Step 5: The electric anchor windlass (5) gradually tightens the recovery cable (6) until the contact mechanism (7) contacts the buoy (4), and the LNG carrier sails away, completing the export operation.

2. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 1 is characterized in that: A ballast tank is provided in the buoy (4), and the restoring stiffness is adjusted by adjusting the ballast amount in the ballast tank.

3. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 1 is characterized in that: A ballast weight (3) is provided at the bottom of the buoy (4).

4. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 1, characterized in that: The contact mechanism (7) comprises an articulated joint (1).

5. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 4 is characterized in that: A spherical joint is provided at the end of the articulated joint (1), and during external transport, the spherical joint engages with a groove on the outer side of the bow of the LNG transport ship.

6. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 5, characterized in that: A mooring cable (9) is provided at the end of the spherical joint, and the mooring cable (9) is connected to a deck anchor machine (10) at the bow of the LNG transport ship during external transmission.

7. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 5, characterized in that: The spherical joint is sleeved with a rubber sheath (8).

8. The method for operating a temporary mooring positioning device for FLNG tail transportation operation according to claim 7, characterized in that: The rubber sheath (8) is detachably connected to the ball joint.

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