A hull condition monitoring and assessment system suitable for FPSO

Abstract

The present invention relates to a hull condition monitoring and assessment system suitable for FPSO, belonging to the technical field of FPSO, comprising a monitoring system for collecting real-time structural strain and a real-time assessment system for assessing the safety of the FPSO, wherein the monitoring system comprises a stress sensor, a fiber optic acceleration sensor and a fiber optic Bragg grating demodulator; the real-time assessment system comprises a total longitudinal strength assessment module and a fatigue strength assessment module. The present invention obtains the total longitudinal bending stress of the hull structure and the fatigue strength stress of key structures during the offshore operation of the FPSO through the hull monitoring system, establishes a graded assessment standard for the total longitudinal safety of the hull structure through the real-time assessment system, and provides safety assessment results of the hull structure, such as the total longitudinal bending stress of the hull structure and the fatigue life of the key structures, in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of FPSO, and in particular relates to a hull condition monitoring and evaluation system suitable for FPSO. Background Art

[0002] Floating production storage and offloading vessels (FPSO) are key facilities for offshore oil development, mainly used for the extraction, processing, storage and transportation of offshore oil, natural gas and other energy sources.

[0003] Currently, FPSO structural safety status assessments primarily rely on loading instruments. The basic principle is that the weight and center of gravity of the main tanks can be calculated based on the liquid level data and liquid cargo density of the main tanks. Combined with the light ship weight distribution and ship statics principles, the hydrostatic bending moment and hydrostatic shear force under the current loading state can be calculated. The criterion for judging the longitudinal strength of the hull is whether the hydrostatic bending moment and hydrostatic shear force curves are below the allowable envelope calculated according to classification society regulations. However, in reality, the hull is subjected to dynamic wave loads in real time, and existing loading instrument systems cannot reflect the wave load component of the hull structural response in real time.

[0004] Therefore, there is an urgent need in the existing technology to obtain the structural response caused by wave loads in real time and propose a real-time assessment technology solution for the total longitudinal strength of the hull structure and the fatigue strength of key nodes. Summary of the Invention

[0005] The problem to be solved by the present invention is to provide a hull condition monitoring and evaluation system suitable for FPSO.

[0006] To solve the above technical problems, the present invention adopts a technical solution: a hull condition monitoring and evaluation system suitable for FPSO, including a monitoring system for collecting real-time structural strain and a real-time evaluation system for evaluating the safety of FPSO.

[0007] The monitoring system comprises:

[0008] Stress sensors, including a total longitudinal strength stress sensor for monitoring the total longitudinal strength and a fatigue strength stress sensor for monitoring the fatigue strength of the node;

[0009] Fiber optic acceleration sensor, used to collect real-time acceleration information of the hull;

[0010] Fiber Bragg grating (FBG) demodulators, including a total longitudinal strength fiber Bragg grating (TLSI) demodulator and a fatigue strength fiber Bragg grating (FGBG) demodulator. The TLSI fiber Bragg grating (FGBG) demodulator is used to demodulate optical signals collected by the TLSI stress sensor and the fiber optic acceleration sensor; the fatigue strength fiber Bragg grating (FGBG) demodulator is used to demodulate optical signals collected by the fatigue strength stress sensor.

[0011] The real-time evaluation system includes a total longitudinal strength evaluation module and a fatigue strength evaluation module. The total longitudinal strength evaluation module includes a connected total longitudinal strength processing module and a total longitudinal bending stress histogram display module. The total longitudinal strength processing module is connected to a total longitudinal strength fiber Bragg grating demodulator.

[0012] The fatigue strength evaluation module includes a fatigue strength processing module and a fatigue life histogram display module connected to each other. The fatigue strength processing module is connected to a fatigue strength fiber Bragg grating demodulator.

[0013] Furthermore, several cross-sectional positions are selected amidships of the hull, and the total longitudinal strength stress sensors are distributed on both sides of the several cross-sectional positions, and the total longitudinal strength stress sensors of each cross-sectional position are symmetrically arranged; the fatigue strength stress sensors are installed on the surfaces of the adjacent structures of the nodes; the fiber optic acceleration sensors are respectively installed at the bow and stern; and the fiber optic Bragg grating demodulator is installed in the control room.

[0014] Furthermore, the total longitudinal strength processing module is also connected to a liquid level monitoring system.

[0015] Furthermore, the total longitudinal strength processing module receives and processes the data demodulated by the total longitudinal strength fiber Bragg grating demodulator to obtain the total longitudinal bending stress value of each cross section. The total longitudinal bending stress bar graph display module is used to display a bar graph of the total longitudinal bending stress of each cross section and display the total longitudinal bending stress value of the corresponding cross section on the right side of the bar graph.

[0016] Furthermore, the hierarchical assessment standards for overall longitudinal safety are:

[0017] When the total longitudinal bending stress value is less than 42Mpa, the bar graph is green, indicating that it is very safe;

[0018] When the total longitudinal bending stress value is between 43 and 84 MPa, the bar graph is yellow, indicating safety;

[0019] When the total longitudinal bending stress value is between 85 and 126 MPa, the bar graph is red, indicating danger;

[0020] When the total longitudinal bending stress value is between 127 and 168 MPa, it is dark red, indicating that it is very dangerous;

[0021] When the total longitudinal bending stress value is between 169 and 210 MPa, the bar graph shows dark red stripes, indicating extreme danger;

[0022] When the total longitudinal bending stress value is greater than 211 MPa, the bar graph will show flashing dark red stripes, and the real-time assessment system will issue an alarm message, indicating that the critical value of damage has been reached.

[0023] Furthermore, the fatigue strength processing module receives and processes the data demodulated by the fatigue strength fiber Bragg grating demodulator to obtain fatigue strength data of the structure around the node. Based on the fatigue strength data, the structural fatigue life is obtained based on Miner's linear cumulative damage theory. The fatigue life histogram display module is used to display a histogram of the fatigue life of the structure around the node.

[0024] The specific effects of the present invention are as follows:

[0025] The present invention obtains the total longitudinal bending stress of the hull structure and the fatigue strength stress of key structures during FPSO operations at sea through the hull monitoring system. At the same time, through the real-time evaluation system, a graded evaluation standard for the total longitudinal safety of the hull structure is established, and the safety evaluation results of the hull structure, such as the total longitudinal bending stress of the hull structure and the fatigue life of key structures, are given in real time.

[0026] The present invention can formulate a reasonable production scale based on the longitudinal strength assessment results, can intuitively recognize the remaining fatigue life of the current key hull structures, and provide a reference for the formulation of operation plans in different marine environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be described in detail below with reference to the accompanying drawings and in combination with examples, and the advantages and implementation modes of the present invention will become more apparent. The contents shown in the accompanying drawings are only used to illustrate the present invention and do not constitute any limitation to the present invention. In the accompanying drawings:

[0028] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0029] like Figure 1 As shown, the present invention is a hull condition monitoring and evaluation system suitable for FPSO, including a monitoring system for collecting real-time structural strain and a real-time evaluation system for evaluating the safety of FPSO.

[0030] The monitoring system includes:

[0031] Stress sensors are used to collect real-time strain of the hull structure; the stress sensors include a total longitudinal strength stress sensor for monitoring the total longitudinal strength and a fatigue strength stress sensor for monitoring the fatigue strength of the nodes;

[0032] Fiber optic acceleration sensor, used to collect real-time acceleration information of the hull;

[0033] Fiber Bragg grating (FBG) demodulators, including total longitudinal strength fiber Bragg grating (FBG) demodulators and fatigue strength fiber Bragg grating (FBG) demodulators. The total longitudinal strength fiber Bragg grating (FBG) demodulator is used to demodulate the optical signals collected by the total longitudinal strength stress sensor and the optical fiber acceleration sensor; the fatigue strength fiber Bragg grating (FBG) demodulator is used to demodulate the optical signals collected by the fatigue strength stress sensor.

[0034] Fiber optic main cable, used for transmission of optical signals throughout the ship;

[0035] Fiber optic splice box, used for splicing optical cables and allocating channels of grating interrogator;

[0036] Router, used for network signal connection and transmission;

[0037] Cabin power supply, used for power supply;

[0038] Monitoring host (virtual computer) used to install, operate and maintain the system;

[0039] Air switch, used for circuit protection.

[0040] In this embodiment, all longitudinal stress sensors are installed on the upper surface of the hull's upper deck. Specifically, five transverse sections were selected amidships, with sensors distributed on both sides of each section. Four longitudinal stress sensors were placed in each section (two on the port and two on the starboard sides), for a total of 20 sensors. Fatigue stress sensors were all installed on the structural surfaces adjacent to the hydraulic tong base, for a total of 30 sensors. Fiber optic acceleration sensors were installed at both the bow and stern, with one at the bow for the single-point cabin and one at the stern for the terminal building, for a total of two. Two fiber optic Bragg grating interrogators (one for longitudinal strength and one for fatigue strength) were installed in the control room. One monitoring host was also installed in the control room.

[0041] The total longitudinal intensity fiber Bragg grating demodulator is located in the control room. Four dual-core optical cables are pulled from the control room, passing through the port and starboard sides, and then back to the control room.

[0042] The fatigue strength fiber Bragg grating demodulator is located in the control room. An 8-core optical cable is pulled through the entire ship to the single-point cabin. Each core is branched in the single-point cabin, and each core can be connected in parallel with 4 to 6 fatigue strength stress sensors.

[0043] The real-time evaluation system includes a total longitudinal strength evaluation module and a fatigue strength evaluation module. The total longitudinal strength evaluation module includes a connected total longitudinal strength processing module and a total longitudinal bending stress bar graph display module. The total longitudinal strength processing module is connected to a total longitudinal strength fiber grating demodulator. The total longitudinal strength processing module is also connected to a liquid level monitoring system, which is existing technology.

[0044] The total longitudinal strength processing module receives and processes the data demodulated by the total longitudinal strength fiber Bragg grating demodulator to obtain the total longitudinal bending stress value of each cross section. The total longitudinal bending stress bar graph display module is used to display a bar graph of the total longitudinal bending stress of each cross section and display the total longitudinal bending stress value of the corresponding cross section on the right side of the bar graph. Since the critical value of the total longitudinal bending stress value is 211 MPa, when the total longitudinal bending stress value is less than 211 MPa, the specific data will be displayed. When the total longitudinal bending stress value is greater than 211 MPa, the specific value will no longer be displayed, and “>211 MPa” will be directly displayed to indicate that the value has exceeded the critical value.

[0045] Each bar chart uses different colors to represent the stress level of each cross section according to the different values ​​of the total longitudinal bending stress, and establishes a graded assessment standard for the total longitudinal safety:

[0046] When the total longitudinal bending stress value is less than 42Mpa, the bar graph is green, indicating that it is very safe;

[0047] When the total longitudinal bending stress value is between 43 and 84 MPa, the bar graph is yellow, indicating safety;

[0048] When the total longitudinal bending stress value is between 85 and 126 MPa, the bar graph is red, indicating danger;

[0049] When the total longitudinal bending stress value is between 127 and 168 MPa, it is dark red, indicating that it is very dangerous;

[0050] When the total longitudinal bending stress value is between 169 and 210 MPa, the bar graph shows dark red stripes, indicating extreme danger;

[0051] When the total longitudinal bending stress value is greater than 211 MPa, the bar graph will show flashing dark red stripes, and the real-time assessment system will issue an alarm message, indicating that the critical value of damage has been reached.

[0052] The longitudinal strength assessment module also processes and displays longitudinal bending moment curves. These curves, against a hull side view, provide detailed information about the bending moments at each critical section. For example, the points on the red curve represent the maximum and minimum longitudinal bending moment ranges for a section, while the green curve represents the actual measured longitudinal bending moment data for that section.

[0053] The fatigue strength assessment module (in this embodiment, the fatigue strength assessment module of the hydraulic tong base) includes a connected fatigue strength processing module and a fatigue life bar graph display module. The fatigue strength processing module is connected to the fatigue strength fiber Bragg grating demodulator.

[0054] The fatigue strength processing module receives and processes the data demodulated by the fatigue strength fiber Bragg grating demodulator to obtain the fatigue strength data of the structure around the hydraulic tong base. Based on the fatigue strength data, the structural fatigue life is obtained based on Miner's linear cumulative damage theory. The fatigue life bar graph display module is used to display a bar graph of the fatigue life of the structure around the hydraulic tong base.

[0055] The method for calculating the total longitudinal bending stress value by the total longitudinal strength processing module is: real-time reading of the liquid level information of the hull liquid tank in the liquid level monitoring system, calculating the various static parameters of the hull, and obtaining the buoyancy distribution and weight distribution of each station on the hull; calculating the hydrostatic bending moment of each station based on the buoyancy distribution and weight distribution, and then calculating the hydrostatic bending stress at the total longitudinal strength stress sensor based on the section modulus of the cross section; the hydrostatic bending stress is superimposed on the wave bending stress obtained by the corresponding total longitudinal strength stress sensor to obtain the total longitudinal bending stress at the total longitudinal strength stress sensor.

[0056] The fatigue strength processing module calculates fatigue life as follows: On the FPSO hull structure, the hydraulic calipers securely connect the buoys to the hull. Due to stress concentration in this area, it primarily bears the force of the anchor chain mooring, the weight of the buoys and turntable, the weight of the slip rings, and the reaction force of the preload. Furthermore, fatigue failure is prone to occur under cyclic wave loads. Therefore, quadratic polynomial interpolation is used to calculate the hotspot stress value (the hotspot stress value is obtained from the fatigue strength stress sensor), and then the structural fatigue life is calculated based on Miner's linear cumulative damage theory.

[0057] The present invention can realize FPSO structural status monitoring (using satellite communication technology to transmit system data to the FPSO land-based intelligent control center in real time) and safety assessment in scenarios such as liquid cargo loading (formulating a reasonable liquid cargo loading strategy based on the evaluation results), high winds and waves (forming a reasonable production scale based on the evaluation results of the total longitudinal strength of the ship under high winds and waves), helicopter take-off and landing (the movement information of the helicopter deck can be displayed intuitively and in real time), daily status of free rotation of the hull (the current cumulative damage degree and remaining fatigue life of the foundation can be intuitively recognized, providing a reference for the formulation of operation plans in different marine environments), and remote interactive display.

[0058] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A hull condition monitoring and assessment system suitable for FPSO, characterized by: Including a monitoring system for collecting real-time structural strain and a real-time assessment system for evaluating FPSO safety, The monitoring system comprises: Stress sensors, including a total longitudinal strength stress sensor for monitoring the total longitudinal strength and a fatigue strength stress sensor for monitoring the fatigue strength of the node; Fiber optic acceleration sensor, used to collect real-time acceleration information of the hull; Fiber Bragg grating (FBG) demodulators, including a total longitudinal strength fiber Bragg grating (TLSI) demodulator and a fatigue strength fiber Bragg grating (FGBG) demodulator. The TLSI fiber Bragg grating (FGBG) demodulator is used to demodulate optical signals collected by the TLSI stress sensor and the fiber optic acceleration sensor; the fatigue strength fiber Bragg grating (FGBG) demodulator is used to demodulate optical signals collected by the fatigue strength stress sensor. The real-time assessment system includes a total longitudinal strength assessment module and a fatigue strength assessment module. The total longitudinal strength assessment module includes a connected total longitudinal strength processing module and a total longitudinal bending stress histogram display module. The total longitudinal strength processing module is connected to a total longitudinal strength fiber Bragg grating demodulator. The fatigue strength assessment module includes a connected fatigue strength processing module and a fatigue life histogram display module. The fatigue strength processing module is connected to the fatigue strength fiber Bragg grating demodulator. The total longitudinal strength processing module is also connected to the liquid level monitoring system; The method for calculating the total longitudinal bending stress value by the total longitudinal strength processing module is as follows: reading the liquid level information of the hull liquid tank in the liquid level monitoring system in real time, calculating various static parameters of the hull, and obtaining the buoyancy distribution and weight distribution of each station of the hull; calculating the hydrostatic bending moment of each station based on the buoyancy distribution and weight distribution, and then calculating the hydrostatic bending stress at the total longitudinal strength stress sensor based on the section modulus of the cross section; superimposing the hydrostatic bending stress with the wave bending stress obtained by the corresponding total longitudinal strength stress sensor to obtain the total longitudinal bending stress at the total longitudinal strength stress sensor; The fatigue strength processing module receives and processes the data demodulated by the fatigue strength fiber Bragg grating demodulator to obtain fatigue strength data of the structure around the node. Based on the fatigue strength data, the fatigue life of the structure is obtained based on Miner's linear cumulative damage theory. The fatigue life histogram display module is used to display a histogram of the fatigue life of the structure around the node. The fatigue strength processing module calculates fatigue life by using quadratic polynomial interpolation to calculate hot spot stress values, which are obtained through fatigue strength stress sensors, and then calculates structural fatigue life based on Miner's linear cumulative damage theory.

2. The hull condition monitoring and assessment system for FPSO according to claim 1, characterized in that: Several cross-sectional positions are selected amidships of the hull, and the longitudinal strength stress sensors are distributed on both sides of the several cross-sectional positions, with the longitudinal strength stress sensors of each cross-sectional position being symmetrically arranged; the fatigue strength stress sensors are installed on the surfaces of the adjacent structures of the nodes; the fiber optic acceleration sensors are respectively installed at the bow and stern; and the fiber optic Bragg grating demodulator is installed in the control room.

3. The hull condition monitoring and assessment system for FPSO according to claim 1 is characterized in that: The total longitudinal strength processing module receives and processes the data demodulated by the total longitudinal strength fiber Bragg grating demodulator to obtain the total longitudinal bending stress value of each cross section. The total longitudinal bending stress bar graph display module is used to display a bar graph of the total longitudinal bending stress of each cross section and display the total longitudinal bending stress value of the corresponding cross section on the right side of the bar graph.

4. The hull condition monitoring and assessment system for FPSO according to claim 3 is characterized in that: The hierarchical assessment standards for overall longitudinal safety are: When the total longitudinal bending stress value is less than 42Mpa, the bar graph is green, indicating that it is very safe; When the total longitudinal bending stress value is between 43 and 84 MPa, the bar graph is yellow, indicating safety; When the total longitudinal bending stress value is between 85 and 126 MPa, the bar graph is red, indicating danger; When the total longitudinal bending stress value is between 127 and 168 MPa, it is dark red, indicating that it is very dangerous; When the total longitudinal bending stress value is between 169 and 210 MPa, the bar graph shows dark red stripes, indicating extreme danger; When the total longitudinal bending stress value is greater than 211 MPa, the bar graph will show flashing dark red stripes, and the real-time assessment system will issue an alarm message, indicating that the critical value of damage has been reached.

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