Anti-sloshing device and control method for oil-water separators on offshore platforms

Abstract

This invention discloses an anti-sloshing device and its control method for an oil-water separator tank on an offshore platform, belonging to the field of offshore oil and gas development equipment. The device includes a tank body, a condition monitoring component (DVL flow meter and wave height meter), symmetrically arranged liftable wave generators, and a control unit. Based on the monitored fluid direction and wave height data, the control unit drives the wave generator on the same side as the flow direction to generate reverse waves with opposite propagation directions and matching wave heights, actively counteracting sloshing. This invention dynamically suppresses liquid sloshing through a closed-loop control system of "monitoring-analysis-reverse wave generation," significantly improving separation stability and efficiency while reducing structural load.

Description

Technical Field

[0001] This invention relates to the field of offshore oil and gas development equipment technology, specifically to an anti-sway device and control method for an oil-water separator tank used on an offshore platform. Background Technology

[0002] When offshore platforms are engaged in oil and gas production, their oil-water separators (mostly horizontal) play a crucial role in separating crude oil from water in the produced fluid through gravity settling. However, under the influence of environmental loads such as waves and sea winds, the platform will experience continuous, multi-degree-of-freedom swaying, which will be transmitted to the separator, causing the liquid inside the tank to slosh violently.

[0003] Liquid sloshing has many adverse effects: First, it disrupts the relatively static environment required for oil-water separation, interfering with the coalescence and sedimentation of oil droplets, resulting in an unclear oil-water interface and reduced separation efficiency; second, the sloshing liquid generates periodic impact loads on the tank wall, which can easily lead to tank structure fatigue and shorten the service life of the equipment in the long run; third, it may induce resonance, posing a threat to the overall safety of the platform.

[0004] Currently, common solutions involve installing passive buffer structures such as fixed baffles inside the tank. However, these structures can only reduce sloshing energy to a certain extent and cannot be dynamically adjusted according to the real-time sloshing status of the platform, resulting in limited suppression effects, especially under harsh sea conditions. Therefore, there is an urgent need for a technical solution that can actively and intelligently suppress liquid sloshing inside the separation tank. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing passive anti-sloshing technologies and provide an anti-sloshing device and control method for oil-water separators on offshore platforms. This device can monitor the sloshing state of the liquid inside the tank in real time and actively generate reverse waves to counteract it, thereby effectively suppressing liquid surface fluctuations, improving oil-water separation efficiency and equipment operation safety.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, an anti-sway device for an oil-water separator tank on an offshore platform includes:

[0008] Tank body, used to hold the oil-water mixture to be separated;

[0009] A condition monitoring component, installed in the inner cavity of the tank, is used to monitor the sloshing state of the liquid inside the tank in real time. It includes a DVL flow meter and a wave height meter.

[0010] The active anti-sway component includes liftable wave-generating plates symmetrically arranged on both sides of the inner cavity of the tank. The liftable wave-generating plates can be raised and lowered along the height direction of the tank and reciprocate to generate waves.

[0011] The control unit is connected to the status monitoring component and the active anti-sloshing component respectively, and is used to control the movement of the liftable wave-generating plate on the same side as the current fluid flow direction according to the flow direction and wave height data collected by the status monitoring component, so as to generate a reverse wave opposite to the propagation direction of the liquid surface sloshing wave.

[0012] Furthermore, the control unit is configured to: receive fluid flow direction data measured by the DVL flow meter to determine the propagation direction of the swaying wave; receive wave height data measured by the wave height meter; control the liftable wave-generating plate on the same side as the swaying wave propagation direction to descend to a set depth, and perform reciprocating motion with an amplitude and frequency matching the wave height.

[0013] Furthermore, the DVL flow meter and the wave height meter are arranged adjacent to each other in the middle region of the tank's internal cavity.

[0014] Furthermore, the distance between the DVL flow meter and the wave height meter does not exceed 0.5m.

[0015] Furthermore, the liftable wave-generating plate is driven to rise and fall by a hydraulic lifting mechanism located outside the tank, and the gap between the plate and the inner wall of the tank is no greater than 5mm.

[0016] Furthermore, the tank is a horizontal separation tank, and a wave-damping beach is provided at the bottom of its inner cavity.

[0017] Secondly, an anti-sway control method based on the aforementioned device includes the following steps:

[0018] S1: The flow direction data and liquid surface wave height data of the fluid in the tank are collected in real time through the status monitoring component;

[0019] S2: The control unit determines the propagation direction of the current liquid surface sloshing wave based on the flow direction data;

[0020] S3: The control unit controls the start of the liftable wave-generating plate on the same side as the propagation direction, and generates a control command based on the wave height data to drive the wave-generating plate to reciprocate in the vertical direction to generate a reverse wave that is opposite to the propagation direction of the swaying wave and matches the wave height.

[0021] S4: The reverse wave and the swaying wave meet inside the tank and cancel each other out, causing the liquid surface to stabilize.

[0022] Furthermore, in step S3, the specific process of generating control commands includes: calculating the target wave height of the reverse wave to be generated based on the wave height data, and determining the vertical reciprocating motion amplitude and frequency of the liftable wave-generating plate accordingly.

[0023] The advantages of this invention over the prior art are:

[0024] Active and precise suppression: This invention breaks through the traditional passive buffering approach and creatively proposes a closed-loop control strategy of "real-time monitoring - intelligent decision-making - active wave generation". By sensing the sway characteristics in real time through sensors, the control unit drives the wave-generating plate to generate waves that are precisely opposite in direction and of equal amplitude (or modulated amplitude) for active interference cancellation. The sway suppression effect is far superior to that of a fixed structure, and can significantly improve the stability of the oil-water separation interface.

[0025] Strong dynamic adaptability: The device can automatically adjust wave-generating parameters (such as wave-generating plate position and motion amplitude and frequency) according to the real-time changes in platform sway (manifested as changes in fluid direction and wave height), realize dynamic optimization control, adapt to different sea conditions from calm to severe, and have good working condition robustness.

[0026] High structural integration and easy modification: The core monitoring and execution components can be directly integrated into the existing horizontal separation tank without large-scale modifications to the main tank structure. The symmetrically arranged liftable wave-generating plates, combined with the same-side response logic, make rational use of space and achieve high execution efficiency, making them particularly suitable for space-constrained applications on offshore platforms.

[0027] Significant overall benefits: By effectively suppressing liquid sloshing, not only is the oil-water separation efficiency and product quality improved, but the load of liquid impact on the tank structure is also greatly reduced, which helps to extend the service life of the equipment, reduce maintenance costs, and improve the overall safety and economy of offshore platform operations. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments or the prior art will be introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the anti-sway device for the oil-water separator tank on the offshore platform according to the present invention.

[0030] Attached reference numerals: 1-Tank body; 2-DVL flow meter; 3-Wave height meter; 4-Liftable wave generator; 5-Break damper; 6-Inlet; 7-Outlet. Detailed Implementation

[0031] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limiting purposes, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details.

[0032] like Figure 1 As shown, the anti-sway device for an oil-water separator tank on an offshore platform according to a preferred embodiment of the present invention is mainly applied to the horizontal oil-water separator tank of an offshore oil and gas production platform.

[0033] The tank 1 is a conventional horizontal cylindrical pressure vessel with an inlet 6 and an outlet 7 at both ends. The tank 1 typically contains wave-damping beaches 5 to assist in smooth flow and initial energy dissipation; the device of this invention is compatible with these beaches and can work in conjunction with them.

[0034] The condition monitoring components are installed inside the tank 1. The DVL flow meter 2 is preferably fixedly installed at the midpoint of the tank 1's length. The acoustic transducer array of the DVL flow meter 2 faces the axial direction of the tank, enabling high-precision measurement of the axial flow direction of the fluid at that location (e.g., defining the outlet side as the positive direction) and instantaneous velocity. The wave height meter 3 is also installed in the mid-area of ​​the tank, preferably adjacent to the DVL flow meter 2, with the distance between the DVL flow meter and the wave height meter not exceeding 0.5m, to monitor the liquid level fluctuations in the same representative area and output wave height data in real time. The DVL flow meter 2 and the wave height meter 3 together constitute a real-time sensing system for the liquid sloshing state (wave propagation direction and energy intensity).

[0035] The core of the active anti-sway assembly consists of two sets of liftable wave-generating plates 4. These are symmetrically installed at the end regions of the tank 1's inner cavity near the inlet and outlet. The surface of each wave-generating plate 4 is approximately parallel to the tank's axis. The liftable wave-generating plates 4 are connected to a hydraulic lifting mechanism (not shown in the figure, but may include a hydraulic cylinder, guide rails, etc.) located outside the tank 1 via a sealing shaft penetrating the tank wall, thereby enabling the plates to reciprocate vertically along the tank. To ensure wave-generating efficiency and reduce energy leakage, the assembly gap between the side of the liftable wave-generating plate 4 and the inner wall of the tank 1 is strictly controlled, typically not exceeding 5mm.

[0036] The control unit (not shown in the figure) can be integrated into the platform's central control system or a separate local control cabinet. It establishes a communication connection via signal cables with the DVL flow meter 2, wave height meter 3, and the drive mechanisms (lifting mechanisms) of the two sets of liftable wave-generating plates 4. The control unit contains a built-in processor, memory, and control algorithm program.

[0037] The working principle and control method of the device of the present invention are as follows:

[0038] Data acquisition (corresponding to method step S1): When the platform shakes, causing the liquid inside the tank to slosh, the DVL flow meter 2 continuously measures the axial flow direction (e.g., if the stable flow direction is measured as "positive," i.e., flowing towards the outlet) and velocity of the fluid in the middle of the tank, and the wave height meter 3 continuously measures the wave height of the liquid surface at that point (e.g., if the wave height H is measured to be 0.3 meters). This data is transmitted to the control unit in real time.

[0039] State determination (corresponding to method step S2): The control unit receives and processes the data. According to the principles of fluid mechanics, the macroscopic directional flow of the fluid indicates the propagation direction of the main sloshing energy (i.e., the dominant sloshing wave). Therefore, the control unit determines that there is currently a sloshing wave propagating towards the discharge port side, and its intensity is quantified by the wave height H.

[0040] Decision and Execution (corresponding to method step S3): Based on the above judgment, the control unit activates the anti-sway strategy. It only sends commands to the liftable wavemaker 4 located on the discharge port side (i.e., the side with the current fluid flow direction). Based on the measured wave height H, the control unit calculates, through a built-in control algorithm model, such as empirical formulas based on wave theory or a pre-calibrated data mapping table, the vertical reciprocating motion amplitude A and frequency f required to generate a reverse wave with a wave height "matching" H, such as equal to H or a certain proportion of H. Then, it drives the liftable wavemaker 4 to perform vertical reciprocating motion with this amplitude A and frequency f.

[0041] Cancellation and Stabilization (corresponding to step S4): The driven, liftable wave generator 4 generates a wave propagating towards the inlet side in the liquid, which is a reverse wave propagating in the exact opposite direction to the original sloshing wave. This reverse wave propagates towards the center of the tank and meets the original sloshing wave from the other side in the central region of the tank. By controlling the wave generation parameters, the two waves are made to be nearly out of phase when they meet, resulting in destructive interference, and their wave energy cancels each other out. As a result, the amplitude of liquid surface fluctuations in most areas of the tank is significantly reduced, restoring stability or leaving only tiny ripples, thus creating a stable fluid environment for oil-water separation.

[0042] Continuous Adaptation: The above process is a continuous loop. The control unit constantly monitors new flow rate and wave height data. Once a change in flow direction (such as flowing towards the feed inlet) or a change in wave height is detected, the control unit will immediately recalculate and may switch to start the wave generator on the other side, or adjust the motion parameters of the current wave generator to achieve dynamic tracking and real-time cancellation of the sloshing state.

[0043] The algorithm in the control unit can be a classic PID control, a more advanced adaptive control, or a fuzzy control algorithm to cope with the nonlinearity and time-varying nature of the system.

[0044] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0045] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An anti-sway device for an oil-water separator tank on an offshore platform, characterized in that, include: Tank (1) is used to hold the oil-water mixture to be separated; A status monitoring component is installed in the inner cavity of the tank (1) to monitor the sloshing state of the liquid in the tank (1) in real time. It includes a DVL flow meter (2) and a wave height meter (3). The active anti-sway component includes a liftable wave-generating plate (4) symmetrically arranged on both sides of the inner cavity of the tank (1). The liftable wave-generating plate (4) can move up and down along the height direction of the tank and reciprocate to generate waves. The control unit is connected to the status monitoring component and the active anti-sway component respectively, and is used to control the action of the liftable wave plate (4) on the same side as the current fluid flow direction according to the flow direction and wave height data collected by the status monitoring component, so as to generate a reverse wave opposite to the propagation direction of the liquid surface sway wave.

2. The anti-sway device for the oil-water separator tank on an offshore platform according to claim 1, characterized in that, The control unit is configured to: receive fluid flow direction data measured by the DVL flow meter (2) and determine the propagation direction of the swaying wave; receive wave height data measured by the wave height meter (3); control the liftable wave plate (4) on the same side as the swaying wave propagation direction to descend to a set depth and reciprocate with an amplitude and frequency matching the wave height.

3. The anti-sway device for the oil-water separator tank on an offshore platform according to claim 1 or 2, characterized in that, The DVL flow meter (2) and the wave height meter (3) are arranged adjacent to each other in the middle region of the inner cavity of the tank (1).

4. The anti-sway device for the oil-water separator tank on an offshore platform according to claim 3, characterized in that, The distance between the DVL flow meter (2) and the wave height meter (3) shall not exceed 0.5m.

5. The anti-sway device for the oil-water separator tank on an offshore platform according to claim 1, characterized in that, The liftable wave-generating plate (4) is driven to rise and fall by a hydraulic lifting mechanism located outside the tank (1), and the gap between the plate of the liftable wave-generating plate (4) and the inner wall of the tank (1) is no greater than 5mm.

6. The anti-sway device for the oil-water separator tank on an offshore platform according to claim 1, characterized in that, The tank (1) is a horizontal separation tank, and a wave-dissipating beach (5) is provided at the bottom of its inner cavity.

7. A method for preventing swaying based on the device according to any one of claims 1-6, characterized in that, Includes the following steps: S1: The flow direction data and liquid surface wave height data of the fluid in the tank are collected in real time through the status monitoring component; S2: The control unit determines the propagation direction of the current liquid surface sloshing wave based on the flow direction data; S3: The control unit controls the start of the liftable wave-generating plate (4) on the same side as the propagation direction, and generates a control command according to the wave height data to drive the wave-generating plate (4) to perform reciprocating motion in the vertical direction, so as to generate a reverse wave that is opposite to the propagation direction of the swaying wave and matches the wave height. S4: The reverse wave and the swaying wave meet inside the tank and cancel each other out, causing the liquid surface to stabilize.

8. The anti-sway control method according to claim 7, characterized in that, In step S3, the specific process of generating control commands includes: calculating the target wave height of the reverse wave to be generated based on the wave height data, and determining the vertical reciprocating motion amplitude and frequency of the liftable wave plate (4) accordingly.

Images