Free landing method for FSRU lifeboat

Abstract

According to the FSRU lifeboat free landing method, a lifeboat frame is fixed to the stern part of a boat, the lifeboat frame is obliquely arranged, a landing guide rail obliquely and downwards extends along the tail part of the lifeboat frame, and the tail part of the landing guide rail extends into water; the landing guide rail is composed of a straight-section guide rail and a curved-section guide rail, rollers are laid on the surface of the straight-section guide rail, the top end point of the curved-section guide rail is tangent to the straight-section guide rail, and the bottom end point of the curved-section guide rail forms an included angle of 3 degrees with the horizontal plane. Truss type supporting frames are fixed to the lower surfaces of the landing guide rails and continuously arranged in the direction of the landing guide rails, and one ends of the supporting frames are fixed to the FSRU stern transom plate. When the lifeboat is released, the lifeboat slides downwards at an angle beta along the lifeboat frame, in the process of sliding, the lifeboat is changed from beta to alpha and then gradually changed to 3 degrees, and finally the lifeboat is released into water in the direction with an included angle of 3 degrees with the horizontal direction, so that free falling is safe falling of the lifeboat in a limited water depth sea area of a wharf, and collision with the seabed is avoided; and casualties are prevented.

Description

Technical Field

[0001] The invention belongs to the field of offshore FSRU design and construction, and in particular relates to a FSRU lifeboat free-falling method. Background Art

[0002] Compared with onshore LNG receiving and gasification terminals, floating LNG receiving and gasification terminals (FSRU) are favored by more and more countries and regions due to their advantages such as short construction period, low investment and environmental protection. Orders have shown explosive growth in recent years.

[0003] FSRU needs to take into account both navigation and dock mooring conditions, which increases the difficulty of its life-saving design, especially the lifeboat design.

[0004] Lifeboats are divided into gravity lifeboats and free-fall lifeboats.

[0005] Under navigation conditions, whether it is a gravity lifeboat or a free-fall lifeboat, FSRU must [1] The design and arrangement of lifeboats can meet the normal use of lifeboats under navigation conditions. [1] SOLAS, International Convention for the Safety of Life at Sea. [S], IMO.2014. However, when the FSRU is moored at the dock for LNG reception, gasification and natural gas export, both the gravity lifeboat and the free-fall lifeboat cannot be used normally for the following reasons: For gravity-type lifeboats, it is difficult to leave the FSRU area after being lowered due to the distribution of mooring lines and the narrow distance between the ship and the shore. For free-fall lifeboats, the water depth at the dock is required to be no less than twice the length of the lifeboat. The water depth at most docks cannot meet the requirement, making it impossible to safely lower the lifeboat. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a free-falling method for a FSRU lifeboat, and the technical solution adopted is: A FSRU lifeboat free-falling method, a lifeboat rack is fixed at the ship's hull, the lifeboat rack is tilted, the lifeboat is fixed on the lifeboat rack, a landing guide rail extends obliquely downward along the tail of the lifeboat rack, and the tail of the landing guide rail extends into the water.

[0007] The landing rail consists of a straight rail and a curved rail. The straight rail is connected to the lifeboat rack. There is a gap Lgap between the straight rail and the lifeboat rack, 5mm≤Lgap≤20mm. Rollers are laid on the surface of the straight rail. The top end of the curved rail is tangent to the straight rail, and the bottom end of the curved rail forms an angle of 3° with the horizontal plane.

[0008] The vertical distance Hz between the top endpoint Pzt and the bottom endpoint Pzb of the straight section guide rail satisfies: Hz=H-Hqa.

[0009] Wherein, H is the distance from the top end point Pzt of the straight section guide rail to the sea surface.

[0010] Hqa is the distance from the top end point of the curved guide rail to the sea surface.

[0011] A truss-type support frame is fixed on the lower surface of the landing rail. The support frame is continuously arranged along the direction of the landing rail, and one end of the support frame is fixed to the FSRU stern cover plate.

[0012] When releasing the lifeboat, the lifeboat slides downward along its lifeboat frame at an angle of β; when it slides to the straight section of the guide rail, the lowering direction of the lifeboat remains unchanged (α=β). When it slides to the curved section of the guide rail, the lowering direction of the lifeboat gradually changes from the initial β to 3°. Finally, the lifeboat is released into the water at an angle of 3° to the horizontal direction, completing the free fall, which is the safe landing of the lifeboat in the limited water depth area of ​​the dock.

[0013] The above-mentioned FSRU lifeboat free fall method further includes that from the top end point of the curved section guide rail to the bottom end point of the curved section guide rail, the curved section guide rail is a part of the fastest curve, and satisfies the following formula: x = k(θ-sinθ); y=k(1-cosθ); is the scale coefficient, which is determined according to the length of the free-fall lifeboat, 20m≤k≤25m.

[0014] θ is the curvature of any point on the curved guide rail.

[0015] In the above-mentioned FSRU lifeboat free-fall method, further, the distance Hqb from the top end point of the curved section guide rail to the sea surface satisfies: Hqb≥Df, where Df is the full load draft of the free-fall lifeboat.

[0016] In the above-mentioned FSRU lifeboat free-fall method, further, the inclination angle α between the straight section guide rail and the horizontal plane is the same as the inclination angle β between the lifeboat rack and the horizontal direction.

[0017] In the above-mentioned FSRU lifeboat free-fall method, further, the vertical distance Hz between the top end point and the bottom end point of the straight section guide rail satisfies: Hz=H-Hqa.

[0018] Among them, H is the distance from the top end point of the straight section guide rail to the sea surface, and Hqa is the distance from the top end point of the curved section guide rail to the sea surface.

[0019] In the above-mentioned FSRU lifeboat free-falling method, further, the bottom end point of the straight section guide rail and the top end point of the curved section guide rail are connected as one by welding.

[0020] In the above-mentioned FSRU lifeboat free-fall method, further, the distance Hqa from the top end point of the curved section guide rail to the sea surface satisfies: Hqa≥0.2k.

[0021] In the above-mentioned FSRU lifeboat free-fall method, further, the support frame is connected to the tail sealing plate of the FSRU by bolts.

[0022] When the method of the present invention is not used, since the free-fall lifeboat itself has a high gravitational potential energy, it relies on the gravitational potential energy to freely fall to the sea surface, and the gravitational potential energy is converted into kinetic energy, so that the free-fall lifeboat has a certain initial velocity when entering the water, so that the free-fall lifeboat will enter the seawater for a certain distance under the action of the initial velocity, and the distance is usually about 2 times the length of the free-fall lifeboat. This lowering method will not cause danger when the FSRU is sailing, but when the FSRU is moored at the dock for LNG receiving and gasification operations, since the dock water depth is usually about ten meters, and the length of the free-fall lifeboat is usually not less than 20 meters, the free-fall lowering method will cause the free-fall lifeboat to collide with the seabed, causing casualties.

[0023] The free-fall lifeboat guide rail lowering method disclosed in the present invention uses a guide rail tooling to gradually change the lowering direction of the free-fall lifeboat from the original β to close to 3° during the lowering process, so that the initial velocity direction when it lands on the water surface is also changed from the original β to about 3°. Therefore, when the lifeboat falls into the water, it will move in the horizontal direction under the action of the initial velocity, and no longer enter the sea water, thereby avoiding the possibility of the free-fall lifeboat hitting the bottom and ensuring the safe escape of personnel. At the same time, since the curved section guide rail is a part of the fastest curve, it is ensured that the lifeboat is lowered in the curved section guide rail part in the shortest time, shortening the escape time.

[0024] The present invention solves the problem that the lifeboat cannot be used during the mooring stage of the FSRU, and ensures the safety and timeliness of the escape of the staff on the FSRU. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a side view structural schematic diagram of the present invention; Figure 2 It is a schematic diagram of the side view structure of the straight section guide rail; Figure 3 1. It is a schematic diagram of the side view structure of the curved section guide rail; Figure 4 It is a schematic diagram of the free-fall lifeboat and davit at the stern of the FSRU when the guide rail tooling of the present invention is not installed; Figure 5 It is a schematic diagram of a lifeboat landing on a straight section of the guide rail after the guide rail tooling of the present invention is installed; Figure 6 It is a schematic diagram of a lifeboat landing on a curved section guide rail after the guide rail tooling of the present invention is installed; Wherein: 1-straight guide rail, 2-curved guide rail, 3-support frame, A-hull, B-free-fall lifeboat, C-lifeboat rack, α-inclination angle of the straight guide rail to the horizontal direction, β-inclination angle of the lifeboat rack to the horizontal direction, Pzt-top endpoint of the straight guide rail, Lgap-gap length between the top endpoint Pzt of the straight guide rail and the lifeboat rack, Pzb-bottom endpoint of the straight guide rail, Hz-distance between the top endpoint Pzt of the straight guide rail and the bottom endpoint Pzb, H-distance from the top endpoint Pzt of the straight guide rail to the sea surface, Hqa-distance from the top endpoint of the curved guide rail to the sea surface, Pqt-top endpoint of the curved guide rail, Pqb-bottom endpoint of the curved guide rail, k-scale coefficient, θ-curvature at any point on the curved guide rail, Hqb-distance from the top endpoint Pqb of the curved guide rail to the sea surface, Df-full load draft of the free-fall lifeboat. DETAILED DESCRIPTION

[0026] The present invention will be further described in conjunction with the accompanying drawings.

[0027] Embodiment 1: The invention discloses a FSRU lifeboat free-falling method, which is applied to the dock landing operation of the FSRU free-falling lifeboat.

[0028] The guide rail tooling is used to assist the landing. The guide rail tooling includes a straight section guide rail, a curved section guide rail and a guide rail support structure, such as Figure 1 shown.

[0029] The straight section guide rail is a straight line, which is the continuation of the lifeboat rack track and plays a transition role from the lifeboat rack to the curved section guide rail. Figure 2 shown.

[0030] The top of the curved rail section is connected to the straight rail section, and the bottom extends to the sea, which plays the role of safely lowering the free-fall lifeboat into the sea. Figure 3 shown.

[0031] When the FSRU is moored at the dock and enters the operational state, its free-fall lifeboat Figure 4 shown.

[0032] Take a certain type of 160-person free-fall lifeboat as an example. The boat is 16.1 meters long, has a full-load draft of 2 meters, and the lifeboat davit inclination angle β=35°. It is used on a certain type of FSRU.

[0033] The 160-person lifeboat is a large lifeboat, so Lgap is selected as 20mm to determine the position of the top endpoint Pzt of the straight segment guide rail.

[0034] The maximum freeboard of the FSRU when moored at the dock is 10.4m. Combined with the position of Pzt, H=13m is determined.

[0035] The 160-person lifeboat is a large lifeboat, so the k value is 25, the Hqa value is 5m, and the Hqb value is 2m.

[0036] Hz = H-Hqa = 8m. α = β = 35°, so the length of the straight section guide rail is 13.948m.

[0037] From the top endpoint Pqt of the curved guideway to the bottom endpoint Pqb of the curved guideway, the guideway satisfies the following formula: x = 25 (θ - sinθ); y=25(1-cosθ); Hqb is not less than the full-load draft of the lifeboat, that is, Hqb ≥ 2m, and Hqb = 2m is taken here. Pqt coincides with Pzb, and the distance from Pqb to the sea surface is Hqb = 2m.

[0038] When a major accident occurs in an FSRU and the crew members need to escape by lifeboat: 1. Open the lifeboat release device, and the lifeboat slides downward along its own davit track at an angle of β; 2. When the lifeboat slides to the straight section of the guide rail, the lowering direction of the lifeboat remains unchanged (α=β). Figure 5 As shown; 3. When sliding to the curved section guide rail, the lowering direction of the lifeboat gradually changes from the initial α to 3°. Figure 6 shown.

[0039] Finally, the lifeboat was released into the water at an angle of 3° to the horizontal direction, completing the free fall, which was a safe landing of the lifeboat in the limited water depth area of ​​the dock.

Claims

1. A FSRU lifeboat free fall method, characterized in that: A lifeboat rack is fixed at the ship's rear, the lifeboat rack is tilted, the lifeboat is fixed on the lifeboat rack, a landing guide rail extends obliquely downward along the tail of the lifeboat rack, and the tail of the landing guide rail extends into the water; The landing rail is composed of a straight rail and a curved rail. The straight rail is connected to the lifeboat rack. There is a gap Lgap between the straight rail and the lifeboat rack, 5mm≤Lgap≤20mm. Rollers are laid on the surface of the straight rail. The top end of the curved rail is tangent to the straight rail, and the bottom end of the curved rail forms an angle of 3° with the horizontal plane. The vertical distance Hz between the top endpoint Pzt and the bottom endpoint Pzb of the straight section guide rail satisfies: Hz=H-Hqa; Wherein, H is the distance from the top end point Pzt of the straight section guide rail to the sea surface; Hqa is the distance from the top end point of the curved section guide rail to the sea surface; A truss-type support frame is fixed on the lower surface of the landing rail. The support frame is continuously arranged along the direction of the landing rail, and one end of the support frame is fixed to the FSRU stern cover plate; When releasing the lifeboat, the lifeboat slides downward along its lifeboat frame at an angle of β; when it slides to the straight section of the guide rail, the lowering direction of the lifeboat remains unchanged. When it slides to the curved section of the guide rail, the lowering direction of the lifeboat gradually changes from the initial β to 3°. Finally, the lifeboat is released into the water at an angle of 3° to the horizontal direction, completing the free fall, which is the safe landing of the lifeboat in the limited water depth area of ​​the dock.

2. A FSRU lifeboat free fall method according to claim 1, characterized in that: From the top end point of the curved rail to the bottom end point of the curved rail, the curved rail is part of the brachistochrone curve and satisfies the following formula: x = k(θ-sinθ); y=k(1-cosθ); is the scale factor, which is determined according to the length of the free-fall lifeboat, 20m≤k≤25m; θ is the curvature of any point on the curved guide rail.

3. A FSRU lifeboat free fall method according to claim 1, characterized in that: The distance Hqb from the top end point of the curved guide rail to the sea surface satisfies: Hqb ≥ Df, where Df is the full load draft of the free-fall lifeboat.

4. A FSRU lifeboat free fall method according to claim 1, characterized in that: The inclination angle α between the straight section guide rail and the horizontal plane is the same as the inclination angle β between the lifeboat rack and the horizontal direction.

5. The FSRU lifeboat free fall method according to claim 1, characterized in that: The vertical distance Hz between the top end point and the bottom end point of the straight section guide rail satisfies: Hz = H-Hqa; Among them, H is the distance from the top end point of the straight section guide rail to the sea surface, and Hqa is the distance from the top end point of the curved section guide rail to the sea surface.

6. A FSRU lifeboat free fall method according to claim 1, characterized in that: The bottom end point of the straight section guide rail and the top end point of the curved section guide rail are connected as one body by welding.

7. A FSRU lifeboat free fall method according to claim 1, characterized in that: The distance Hqa from the top end point of the curved section guide rail to the sea surface satisfies: Hqa ≥ 0.2k.

8. The FSRU lifeboat free fall method according to claim 1, characterized in that: The support frame is connected to the tail plate of the FSRU by bolts.

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