Flexible reinforcement structure for an internal turret FPSO mooring system

Abstract

The present application relates to a kind of inner rotating tower FPSO mooring system flexible reinforcing structure, moon pool cylinder upper part and lower part adopt horizontal ring rib support, moon pool cylinder middle part is rigidly welded with support bulkhead, support deck;Moon pool cylinder is welded with main bearing base, and vertical force, a part of horizontal force, bending moment, torque load is transferred to moon pool cylinder;Lower sliding ring base is connected with moon pool cylinder by welding, sliding block is set outside lower sliding ring and transfers horizontal force.The present application avoids structure hard point by using flexible design in the position of main bearing base and lower sliding ring base, ensures structural coordinated deformation and then ensures to reduce the influence on sliding ring movement.By flexible design, the reinforcing structure under deck is reduced, and the alignment structure is also reduced.The structure weight is reduced, the structure form is simplified, the defects in construction process are avoided to the greatest extent, the strength fatigue characteristics are improved, and the construction difficulty is reduced.

Description

Technical Field

[0001] This invention relates to a flexible reinforcement structure for an FPSO internal turret mooring system, and particularly to a design for a flexible reinforcement structure for an FPSO internal turret under harsh sea conditions, belonging to the field of marine engineering design and manufacturing technology. Background Technology

[0002] Floating Production Storage and Offloading (FPSO) systems are high-end marine engineering equipment that integrates oil and gas production, storage, and export. The internal turret single-point mooring system boasts advantages such as strong adaptability to extreme sea states and minimal restrictions on the number of access channels, making it the crown jewel of single-point mooring systems. Located at the bow, the FPSO's internal turret system bears both the loads from the hull beams and the mooring loads transmitted from the mooring system, making it one of the most critical locations in the structural design of an internal turret FPSO.

[0003] The conditions in each offshore oil field are complex, and the FPSOs used are of different sizes and configurations, with a high degree of customization for individual point systems.

[0004] Conventional internal turret FPSO single-point systems aim to minimize the impact of overall hull deformation on the single-point system. To reduce this impact, the critical interface is located at the hull neutral axis. Simultaneously, during the design phase, efforts are made to strengthen local structures to ensure sufficient stiffness and thus reduce structural deformation.

[0005] However, conventional rigid designs often involve a large number of local components to ensure sufficient local stiffness. This not only brings construction difficulties, but also increases the number of fatigue hotspots due to the large number of structural components near critical areas. Furthermore, since there are often abrupt changes in stiffness between the hull and single-point systems, the local stress concentration is more severe, which increases the probability of cracks.

[0006] In conventional rigid design structures, the strength and fatigue hazard points are often near the single-point system hazard. Once fatigue cracks appear, they will lead to oil and gas leaks, which may cause huge economic losses. Therefore, the reliability and maintainability of their design and construction must be given utmost attention. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a flexible reinforcement structure for an internal turret FPSO mooring system. This structure is simple to construct, safe and reliable, and saves weight.

[0008] To achieve the above objectives, the technical solution of the present invention is: a flexible reinforcement structure for an inner turret FPSO mooring system, comprising: a moon pool cylinder, a main bearing base, and a sliding ring; the upper and lower parts of the moon pool cylinder are supported by horizontal ring ribs, and the middle part of the moon pool cylinder is rigidly welded to the support bulkhead and the support deck; the moon pool cylinder is welded to the main bearing base to transfer vertical force, a portion of horizontal force, bending moment, and torque load to the moon pool cylinder; the sliding ring base is connected to the moon pool cylinder by welding, and a slider is provided on the outer side of the sliding ring to transfer horizontal force.

[0009] Furthermore, the moon pool cylinder transfers the load to the hull through the platform structure and supporting bulkheads, and the connection between the transverse and longitudinal supporting bulkheads and the moon pool cylinder is only in the middle part of the moon pool cylinder; vertical ribs are set in the middle part of the moon pool cylinder to increase the moon pool cylinder's ability to resist yielding and buckling.

[0010] Furthermore, the transverse and longitudinal support bulkheads in the middle section of the moon pool cylinder are arranged radially toward the center, or parallel to the center surface.

[0011] Furthermore, the transverse and longitudinal support bulkheads are locally thickened at the upper and lower parts of the middle of the lunar pool cylinder, and the roots of the thickened plates are designed with Ω holes to release stress.

[0012] Furthermore, horizontal ribs are provided above and below the base of the sliding ring, with the horizontal ribs being a certain distance away from the base of the sliding ring to avoid affecting the coordinated deformation of the sliding ring.

[0013] Furthermore, the upper part of the moon pool cylinder and the main bearing base are not connected to the main deck to avoid deformation of the main deck affecting the operation of the main bearing.

[0014] Furthermore, a cofferdam structure is installed on the main deck to prevent water from the deck from affecting the main bearing.

[0015] Furthermore, the lower part of the moon pool cylinder's sliding ring base adopts a soft-toe structure at the upper and lower positions to avoid local stress concentration.

[0016] Furthermore, the thickness of the middle plate of the moon pool cylinder is 25-70mm, the thickness of the upper plate of the moon pool cylinder is 40-100mm, and the thickness of the lower plate of the moon pool cylinder is 50-120mm.

[0017] Furthermore, the thickness of the support bulkhead is 15–60 mm.

[0018] The beneficial effects of this invention are:

[0019] This invention transmits horizontal force through a slider located on the outer side of the slip ring, and transmits vertical force, bending moment, and torque through the main bearing base. The flexible design of the main bearing base and slip ring base positions avoids structural hard points and prevents structural deformation from affecting the movement of the slip ring.

[0020] The main bearing base is not welded to the main deck to prevent deformation of the entire ship from affecting the deformation of the main bearing base, which in turn affects the deformation of the main bearing and thus affects its rotation.

[0021] The flexible design reduces the number of sub-deck reinforcement structures and alignment structures. This lowers the structural weight, simplifies the structural form, minimizes construction defects, improves strength and fatigue characteristics, and reduces construction difficulty.

[0022] This invention reduces the difficulty of integrating the hull and mooring system, lowers the requirements for construction precision, and increases the reliability of the reinforced structure and mooring system.

[0023] This invention incorporates a deck cofferdam to prevent waves on the deck from affecting the cabin's water ingress and thus impacting stability.

[0024] This invention is a flexible reinforcement structure for an internal turret FPSO mooring system that features high structural utilization efficiency, low construction difficulty, low integration difficulty, and high reliability. Attached Figure Description

[0025] Figure 1 This is a longitudinal section view of the flexible reinforcement structure of the inner turret FPSO mooring system;

[0026] Figure 2 A cross-sectional plan view of the upper layer of the moon pool cylinder, which is part of the flexible reinforcement structure of the inner turret FPSO mooring system.

[0027] Figure 3 A cross-sectional view of the middle layer of the moon pool cylinder, which is part of the flexible reinforcement structure of the inner turret FPSO mooring system.

[0028] Figure 4 This is a cross-sectional plan view of the lower layer of the moon pool cylinder, which is part of the flexible reinforcement structure of the inner turret FPSO mooring system. Detailed Implementation

[0029] 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, and 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.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the present invention.

[0032] Please see Figures 1 to 4As shown in the figure, an embodiment of the present invention illustrates a flexible reinforcement structure for an internal turret FPSO mooring system, which includes a main bearing base 1, a moon pool cylinder 2, horizontal ring reinforcement 3, a deck cofferdam 4, a main deck 5, a platform structure 6, a supporting bulkhead 7, a glide slope ring base ring reinforcement 8, a glide slope ring base 9, a soft toe connection structure 10, and a moon pool cylinder vertical reinforcement 11.

[0033] Specifically, the moon pool cylinder 2 is welded to the main bearing base 1, transferring vertical force, a portion of horizontal force, bending moment, torque, and other loads to the moon pool structure. The sliding ring base 9 is welded to the moon pool cylinder 2, and the sliding ring transmits horizontal force through the slider.

[0034] Furthermore, the moon pool cylinder 2 transfers the load to the hull through the platform structure 6 and the support bulkhead 7, and the connection between the transverse and longitudinal support bulkhead 7 and the moon pool cylinder 2 exists only in the middle part of the moon pool cylinder 2.

[0035] Furthermore, the upper part of the moon pool cylinder 2 adopts a horizontal ring rib to avoid welding with the main bearing base 1.

[0036] Furthermore, horizontal ring ribs are also provided above and below the lower sliding ring base 9. The horizontal ring ribs are a certain distance away from the lower sliding ring base 9 to avoid affecting the coordinated deformation of the lower sliding ring.

[0037] Furthermore, the transverse and longitudinal support bulkheads 7 in the middle part of the moon pool cylinder 2 can be arranged radially toward the center or parallel to the center surface.

[0038] Furthermore, the transverse and longitudinal support bulkhead 7 adopts a locally thickened plate form at the upper and lower middle positions of the moon pool cylinder 1, and the root of the thickened plate adopts an Ω hole form to release stress.

[0039] Furthermore, the lower part of the moon pool cylinder 2 adopts a soft toe connection structure 10 at the connection position between the platform structures 6 to avoid local hard spots.

[0040] Furthermore, the main bearing base 1 is not welded to the main deck 5, and a deck cofferdam 4 is installed on the main deck 5 to reduce the amount of deck water entering the lower compartments.

[0041] Furthermore, vertical ribs 11 are provided in the middle part of the moon pool cylinder 2 to increase the moon pool cylinder 2's resistance to yielding and buckling.

[0042] Furthermore, the moon pool cylinder 2 and the strong reinforcing components are welded with full penetration weld.

[0043] Furthermore, the thickness of the upper plate of the moon pool cylinder 2 is 40-100mm.

[0044] Furthermore, the thickness of the lower plate of the moon pool cylinder 2 is 50-120mm.

[0045] Furthermore, the thickness of the supporting bulkhead plate 7 is 15-60mm.

[0046] Furthermore, a single-point sliding ring is provided at the lower part of the moon pool cylinder 2, and the sliding ring is directly welded to the moon pool cylinder 2.

[0047] Furthermore, the upper part of the moon pool cylinder 2 is welded and aligned with the main bearing support structure of the mooring system, and the local hull transition elbow plate at the sliding ring position is not welded to the moon pool cylinder 2.

[0048] Furthermore, the inner turret FPSO mooring system features a flexible reinforced structure, with key welds using C-type grinding to enhance the overall fatigue resistance of the supports.

[0049] Furthermore, the flexible reinforcement structure of the inner turret FPSO mooring system can be optimized by using optimization algorithms to improve the local plate thickness configuration, ensuring a good match between reinforcement strength and fatigue.

[0050] In a preferred embodiment of the present invention, the positions of the soft toe, platform, and bulkhead can be adjusted as needed; the diameter of the cylinder can be adjusted according to the actual location of the ship's equipment. The flexible design can reduce the level of local stress concentration, reduce stress, improve the fatigue resistance of key structures, reduce the shipowner's operating risks and costs, and improve operating efficiency.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the implementation method and protection scope of the present invention. Those skilled in the art should realize that all solutions obtained by equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A flexible reinforcement structure for an internal turret FPSO mooring system, characterized in that, include: The moon pool cylinder, main bearing base, and sliding ring are structurally integrated. The upper and lower parts of the moon pool cylinder are supported by horizontal ring ribs, and the middle part of the moon pool cylinder is rigidly welded to the support bulkhead and support deck. The moon pool cylinder is welded to the main bearing base to transfer vertical force, a portion of horizontal force, bending moment, and torque load to the moon pool cylinder. The sliding ring base is connected to the moon pool cylinder by welding, and a slider is installed on the outside of the sliding ring to transfer horizontal force. The moon pool cylinder transfers load to the hull through the platform structure and support bulkhead. The connection between the transverse and longitudinal support bulkheads and the moon pool cylinder is only in the middle part of the moon pool cylinder. Vertical ribs are installed in the middle part of the moon pool cylinder to increase its resistance to yielding and buckling. The upper part of the moon pool cylinder and the main bearing base are not connected to the main deck to avoid the main deck deformation affecting the operation of the main bearing. The sliding ring base at the bottom of the moon pool cylinder adopts a soft toe structure at the upper and lower positions to avoid local stress concentration.

2. The flexible reinforcement structure for the internal turret FPSO mooring system according to claim 1, characterized in that: The transverse and longitudinal support bulkheads in the middle section of the moon pool cylinder are arranged radially toward the center, or parallel to the center surface.

3. The flexible reinforcement structure for the inner turret FPSO mooring system according to claim 1, characterized in that: The transverse and longitudinal support bulkheads are locally thickened at the upper and lower parts of the middle of the moon pool cylinder, and the roots of the thickened plates are designed with Ω holes to release stress.

4. The flexible reinforcement structure for the inner turret FPSO mooring system according to claim 1, characterized in that: Horizontal ribs are set above and below the base of the sliding ring, and the horizontal ribs are set at a certain distance from the base of the sliding ring to avoid affecting the coordinated deformation of the sliding ring.

5. The flexible reinforcement structure for the inner turret FPSO mooring system according to claim 1, characterized in that: A cofferdam structure is installed on the main deck to prevent water from the deck from affecting the main bearing.

6. The flexible reinforcement structure for the inner turret FPSO mooring system according to claim 1, characterized in that: The thickness of the middle plate of the moon pool cylinder is 25~70mm, the thickness of the upper plate of the moon pool cylinder is 40~100mm, and the thickness of the lower plate of the moon pool cylinder is 50~120mm.

7. The flexible reinforcement structure for the inner turret FPSO mooring system according to claim 1, characterized in that: The thickness of the support bulkhead is 15~60mm.

Images