Working method of a self-cleaning device for ballast water pipes of a tropical research vessel

Abstract

The application discloses a self-cleaning device for a ballast water pipeline of a tropical scientific research ship, which is composed of a ballast water pipeline, a double-rod fixing device, a spin blocker, a screw rod and a rotary scraper, the double-rod fixing device is used for fixing and welding the screw rod on the inner wall of the ballast water pipeline, the rotary scraper is fixed on the screw rod through thread engagement and is limited by the spin blockers on both sides, a silicon nitride ceramic shaft seal is arranged at the through interface of the screw rod and the double-rod fixing device, the main body of the rotary scraper is made of a metal alloy base body and is coated with an Al2O3-TiO2 coating on the surface, and the working principle of the self-cleaning device for the ballast water pipeline of the tropical scientific research ship is also disclosed. According to the special requirements of the working area of the tropical scientific research ship, the rotary scraper is driven by the flow energy of the ballast water, the biological membrane is efficiently and quickly removed through fluid centrifugal peeling and shearing peeling, the pollution of chemical cleaning to sensitive ecology such as coral reefs is avoided, and the pipeline blockage risk and maintenance cost are reduced.

Description

Technical Field

[0001] This invention relates to a pipeline cleaning device, and more particularly to a method for operating a self-cleaning device for ballast water pipelines on a tropical research vessel. Background Technology

[0002] During current ballast water pipeline transportation, dissolved organic matter such as proteins and polysaccharides in the ballast water adsorbs and forms a biofilm. Subsequently, bacteria and algae attach through electrostatic interactions, secreting EPS (extracellular polymeric substances) to form a slime layer. With the addition of protozoa and algal spores, the biofilm thickens, eventually leading to the attachment of barnacle larvae and the formation of a hardened calcified layer. Biofouling poses a significant threat to ballast water pipelines, including decreased flow and efficiency, accelerated pipeline corrosion, soaring maintenance costs, and increased risk of system failure.

[0003] The existing mainstream treatment methods all have shortcomings: chemical cleaning technology accelerates pipe pitting corrosion by using reinforcing agents such as sodium hypochlorite, which shortens the pipe life by 40% and generates carcinogenic halogenated hydrocarbons, which seriously damages the coral reef ecosystem. In addition, each cleaning requires a 48-hour shutdown. Traditional mechanical scraping cleaning blades need to maintain a gap of more than 2mm between the blade and the pipe wall to prevent jamming, which makes it impossible to remove the biofilm layer. The rotary shaft seal uses a rubber shaft seal, which is prone to aging and leakage at temperatures above 30°C. Furthermore, it relies too much on external motor drive, resulting in high energy consumption, which is not suitable for the limited power reserves of research vessels.

[0004] Therefore, a great deal of research is still needed on how to clean the inside of the ballast water pipes of tropical research vessels in an environmentally friendly and efficient manner. Summary of the Invention

[0005] Purpose of the invention: This invention addresses the three core pain points of high biological activity, environmental sensitivity, and low flow rate operation in ballast water pipelines of tropical research vessels. It provides a turbine-type self-cleaning device and design method, which can make up for the shortcomings of existing treatment methods in terms of environmental protection, cleaning efficiency, and energy consumption.

[0006] Technical solution: A self-cleaning device for ballast water pipelines of tropical research vessels, comprising a ballast water pipeline, a double-rod fixing device arranged at one end near the length direction of the ballast water pipeline along the direction of water flow in the ballast water pipeline, a screw inserted into a rotary bearing located in the gap of the double-rod fixing device along the direction of water flow in the ballast water pipeline, a rotary scraper arranged on the side of the screw near the double-rod fixing device, a silicon nitride ceramic shaft seal provided on the contact side between the screw passing through the rotary bearing of the double-rod fixing device and the rotary bearing, and the head of the screw passing through the silicon nitride ceramic shaft seal being exposed and forming a regularly shaped end face.

[0007] By designing a rotating scraper located at the end of the ballast water pipeline, the high-frequency shear force of the Karman vortex street formed can act on the entire ballast water pipeline wall behind that end.

[0008] By employing silicon nitride ceramic shaft seals, compared to traditional rubber seals, this invention utilizes the micro-convex end face topology to maintain a stable 0.02 mm-level air film isolation layer, completely blocking the ballast water permeation path, resulting in a leakage rate of 0, which meets environmental protection requirements. Ultimately, while ensuring permanent maintenance-free sealing performance, it achieves zero-leakage operation of the transmission system throughout its entire life cycle.

[0009] The blades of the rotating scraper need to meet the requirement that the fluid flow direction forms a non-orthogonal impact with the rotation axis of the rotating scraper at an angle of 22°±1°.

[0010] The screw is a screw with a double-ended trapezoidal thread.

[0011] The screw passes through the head of the double-rod fixing device with a regular-shaped end, taking a hexagonal end as an example, which allows for positioning and installation with the mounting side to prevent displacement. At the same time, when the research vessel is docked, a backup drive device can be connected to drive the screw to continue working.

[0012] Furthermore, a pair of anti-rotation devices are provided on both sides of the rotating scraper on the screw to prevent the rotating scraper from axially displacing on the screw.

[0013] To prevent the rotating scraper from axially displacing on the screw, which could cause part of the ballast water pipe wall to fall outside the formation range of the Karman vortex street.

[0014] Furthermore, the rotary scraper is a rotary scraper made of metal alloy material.

[0015] Furthermore, the surface of the rotating scraper is coated with an Al2O3-TiO2 coating.

[0016] The rotating scraper body is made of a metal alloy substrate, which provides structural rigidity to withstand the continuous impact of high-velocity fluid. The Al2O3-TiO2 coating attached to the substrate surface disturbs the flow field distribution in the near-wall region through its micro-nano-scale geometry, inducing a periodic Karman vortex street phenomenon at the scraper edge. The resulting high-frequency shear force field effectively decomposes the bio-adhesive layer on the pipe wall. In addition, the composite structure of the metal alloy substrate and the ceramic coating reduces the risk of erosion while maintaining the geometric stability of the scraper edge, avoiding the gap loss phenomenon caused by wear in traditional cleaning devices, and ensuring the long-term operational reliability and continuous optimization of the pipeline self-cleaning system's delivery efficiency.

[0017] Furthermore, there is a gap of 0.1~0.3mm between the edge of the rotating scraper blade and the wall of the ballast water pipe.

[0018] To prevent damage to the blades caused by friction between the blades and microbial residues or other obstructions due to excessively small gaps at the blade edges, the high-speed rotation of the scraper under fluid drive generates centrifugal stripping action, causing the deposits attached to the pipe wall to be stripped off by radial acceleration, thus avoiding tropical biological residues. Furthermore, this precise gap creates high-intensity shear turbulence within the fluid boundary layer, breaking down the stubborn adhesive layer on the pipe wall through fluid shear stripping action.

[0019] Furthermore, the screw and the double-rod fixing device are connected by a Ni80Cr20 transition layer welded by electron beam welding, and the weld throat thickness is not less than 1 / 2 of the shaft diameter.

[0020] Ensure fatigue fracture resistance under extreme conditions of strong water flow impact in tropical seas.

[0021] Furthermore, the double-rod fixing device and the rotating scraper wall near the double-rod fixing device side are metallurgically bonded by laser self-fusion welding.

[0022] Significantly improves the interfacial bonding strength under alternating stress.

[0023] Furthermore, the double-rod fixing device consists of a pair of fixing rods, with the two fixing rods arranged in parallel and the ends of the fixing rods welded to the wall of the ballast water pipeline.

[0024] Furthermore, the double-bar fixing device is installed near the inlet of the ballast water pipeline.

[0025] This allows the resulting Karman vortex street to act on the entire ballast water pipeline.

[0026] Working principle of a self-cleaning device for ballast water pipelines on tropical research vessels:

[0027] When the research vessel is traveling at low speed in the tropics to carry out scientific research operations, the water flows into the ballast water pipe and drives the rotating scraper to rotate. When the rotating scraper rotates under the drive of the fluid, the centrifugal stripping effect generated by its rotation causes the sediment attached to the pipe wall to be stripped off the pipe wall by radial acceleration, thus avoiding the residue of tropical organisms.

[0028] Simultaneously, driven by the rotating scraper, the flow velocity of the water in the ballast water pipe increases. According to the Reynolds number calculation formula of the Karman vortex street: ,in, For fluid density, For flow rate, The feature size of the obstacle. Due to the fluid dynamic viscosity, the characteristics of tropical water bodies make... >40, symmetrical vortices begin to periodically detach, forming a regular Karman vortex street. The Karman vortex street generates high-frequency shear force on the ballast water pipeline wall, causing the tropical biological residues attached to the ballast water pipeline to detach.

[0029] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0030] This invention, based on the fluid flow patterns of ballast water within ballast water pipelines, primarily designs a turbine-type self-cleaning device for ballast water pipelines. The helical surface curvature of the rotating scraper is determined through fluid simulation optimization. This design perfectly aligns with the requirement that starting torque can be generated even under low-velocity ballast water (≥0.5 m / s). Specifically, the helical surface of the rotating scraper is driven by the kinetic energy of the ballast water fluid to generate rotational torque. The fluid flow direction forms a non-orthogonal impact with the scraper's rotation axis at a 22°±1° angle. Through the continuous guiding effect of the helical surface, the normal impact force of the fluid is converted into a tangential rotational force, enabling the rotating scraper to achieve a 360° uniform rotation around the screw. The rotational torque is transmitted to the screw via the trapezoidal thread structure inside the scraper, and finally, the axial load is distributed to the inner wall of the pipeline through a dual-axis fixing device. The entire process is driven by the kinetic energy of the ballast water itself.

[0031] This invention achieves efficient cleaning by controlling the dynamic gap of the blade edge of the rotating scraper to maintain a dynamic gap of 0.1~0.3mm between the blade edge and the inner wall of the ballast water pipe. This dynamic gap is achieved through a dual mechanism of centrifugal peeling and shear peeling.

[0032] The connection interface between the screw and the dual-shaft fixing device designed in this invention forms a nickel-based alloy transition layer through electron beam welding. The weld throat thickness is optimized to be no less than 1 / 2 of the shaft diameter, ensuring fatigue fracture resistance under extreme conditions of strong water flow in tropical seas. Simultaneously, the assembly interface between the screw and the scraper rotary damper is achieved through laser self-fusion welding to achieve metallurgical bonding, significantly improving the interface bonding strength under alternating stress. Furthermore, a silicon nitride ceramic shaft seal component is installed on the part of the screw that penetrates the dual-shaft fixing device. This non-contact dynamic sealing structure utilizes the micro-convex end face topology to maintain a stable 0.02 mm-level gas film isolation layer, completely blocking the ballast water permeation path, resulting in a leakage rate of 0, which meets environmental protection requirements. Ultimately, while ensuring permanent maintenance-free sealing performance, it achieves zero-leakage operation throughout the entire life cycle of the transmission system.

[0033] Furthermore, the present invention features a pre-exposed, regularly shaped end face of the screw. When the ballast water flow velocity is below 0.3 m / s or when self-cleaning is not possible while the research vessel is moored, the output shaft of the auxiliary drive motor can be mechanically coupled to the end face of the screw head via a coupling, using the motor torque to force the three-bladed scraper to rotate. The hexagonal prism structure of the screw head is precisely machined to a geometry with a coaxiality error ≤0.02 mm, ensuring that the motor drive torque is efficiently converted into the tangential rotational force of the scraper through the double-ended trapezoidal thread, maintaining a dual cleaning mechanism of centrifugal peeling and fluid shearing. Simultaneously, the rotational speed of the auxiliary drive motor is controlled to be synchronized with the scraper rotational speed (120±10 rpm) under the design flow velocity of 0.5 m / s, avoiding coating peeling or gap loss due to overspeed rotation. This design extends the self-cleaning function under special conditions through mechanical energy compensation, completely eliminating the risk of pipeline blockage caused by insufficient flow velocity, and ensuring the operational reliability of the ballast water delivery system under all operating conditions. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the turbine-type self-cleaning device for ballast water pipelines according to the present invention.

[0035] Figure 2 A schematic diagram of the turbine-type self-cleaning device for ballast water pipelines of the present invention, viewed from another direction;

[0036] Figure 3 This is a schematic diagram of the double-rod fixing device of the present invention;

[0037] Figure 4 This is a schematic diagram of the screw of the present invention;

[0038] Figure 5 This is a schematic diagram of the three-blade rotating scraper of the present invention;

[0039] Figure 6 This is a schematic diagram of the connection interface between the screw and the double-rod fixing device of the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0041] Example

[0042] As shown in Figures 1 to 5, the implementation process of the turbine-type self-cleaning device for ballast water pipelines of tropical research vessels provided in the embodiments of the present invention is as follows:

[0043] Device installation and positioning: In view of the special environment of the tropical research vessel operation area (water temperature 30~32℃, high biological activity), the self-cleaning device is hoisted and positioned inside the ballast water pipeline in the key transportation section (such as the pipeline section near the sampling port and drainage port) that is associated with sensitive ecological areas such as coral reefs.

[0044] By installing double-rod fixing devices 2 welded to the inner wall of the ballast water pipeline 1 on both sides, the screw 3 can be installed along the length of the ballast water pipeline 1. Considering the accelerated corrosion effect of tropical high-temperature seawater on metals, the connection interface between the screw 3 and the double-rod fixing device 2 is formed by electron beam welding to form a Ni80Cr20 transition layer 8. This transition layer can significantly improve the resistance to intergranular corrosion in a high-salt seawater environment of 30~32℃. At the same time, it is ensured that the weld throat thickness is not less than 1 / 2 of the shaft diameter to withstand the alternating load under the impact of strong water flow in tropical seas and avoid device failure due to corrosion fatigue.

[0045] Rotary scraper 5 assembly: A three-bladed rotary scraper 5 suitable for tropical high-biological-activity environments is assembled on the screw 3.

[0046] The specific operation includes: precisely engaging the internal thread structure of the rotating scraper 5 with the double-ended trapezoidal thread on the rotating shaft to ensure that there are no gaps on the engagement surface (to prevent tropical algae spores and protozoa from hiding).

[0047] Subsequently, an Al2O3-TiO2 coating is completely coated onto the surface of the rotating scraper 5 using an atmospheric plasma spraying process. This coating maintains a stable micro-nano roughness (Ra=0.8μm) at a water temperature of 30-32℃, enhancing the removal effect on rapidly growing tropical biofilms through boundary layer perturbation. Special attention must be paid during assembly, using a laser micrometer to calibrate the dynamic gap between the scraper blade edge and the pipe wall, ensuring it is strictly maintained within the range of 0.1~0.3mm. This gap design precisely removes early-stage attachment organisms common in tropical waters, such as barnacle larvae and calcified algae, preventing them from rapidly forming a hard calcified layer that clogs the pipe.

[0048] Sealing system integration: At the dynamic sealing interface of the rotating bearing 4 through the double rod fixing device 2, a silicon nitride ceramic shaft seal 6 adapted to the requirements of tropical environmentally sensitive areas is installed.

[0049] The micro-convex end face topology and precise fit of the silicon nitride ceramic shaft seal 6 can stably form an air film isolation layer of approximately 0.02 mm in a seawater environment of 30~32℃, achieving zero-leakage operation and completely preventing biological pollutants carried by ballast water from permeating to the outside of the pipeline, thus avoiding secondary pollution to sensitive ecological areas such as coral reefs. Meanwhile, a laser self-fusion welding process is used at the assembly interface between the scraper rotary damper 7 and the screw 3 to form a metallurgical bond, improving the structural reliability under alternating stress in the high humidity and high salt spray environment of tropical seas.

[0050] System Function Verification: The ballast water system of the tropical research vessel was activated. When the water flow velocity reached the typical low flow velocity (0.5 m / s) for tropical operations, it was verified whether the three-bladed rotating scraper 5 was driven by fluid kinetic energy to rotate. It was observed whether the rotating scraper 5 continuously converted the normal impact force into tangential rotational force through a helical surface (the fluid flow direction and the rotation axis form an angle of 22°±1°), achieving a 360° uniform rotation (suitable for low flow velocity conditions on tropical research vessels). Simultaneously, the following key performance characteristics were tested for tropical environmental features:

[0051] Centrifugal stripping effect: It was confirmed that the rotating scraper 5 generates a centrifugal acceleration of more than 2000g, which can forcibly strip shellfish larvae and calcareous algae deposits with a diameter of ≤5mm, which are common in tropical seas, from the tube wall, and prevent them from rapidly developing into calcified layers at a suitable temperature of 30-32℃.

[0052] Shearing and peeling effect: Observe the gap area using high-speed photography to see if dv / dy≥10 is formed. 5 s -1 The shear layer has a shear stress τ≥50Pa, which can effectively decompose EPS biofilms secreted by tropical algae and bacteria (the EPS layer is thicker and more viscous in tropical high biological activity environments).

[0053] Sealing performance: Check whether the six silicon nitride ceramic shaft seals achieve zero leakage to ensure that ballast water will not carry biological pollutants and leak into the environmentally sensitive areas where the research vessel is operating;

[0054] Torque transmission: The trapezoidal thread structure inside the rotating scraper 5 is confirmed to effectively transmit the rotational torque to the screw 3, and the axial load is distributed to the pipe wall through the double rod fixing device 2, ensuring the structural stability during long-term operation of the tropical research vessel.

[0055] Backup drive system activation: When the tropical research vessel is anchored in a coral reef area (flow velocity continuously below 0.3 m / s for more than 30 minutes), or when the ballast water flow velocity decreases due to sampling operations (as determined by flow sensor monitoring), a backup drive scheme adapted to the research vessel's power reserve characteristics will be implemented:

[0056] The output shaft of the auxiliary drive motor (not shown) is connected to the screw head at the end of the threaded shaft 3 via a flexible coupling (not shown). The screw head is a hexagonal prism structure with a width across sides of 24mm and a coaxiality error with the shaft ≤0.02mm.

[0057] The motor controller is activated to increase the speed to 120±10rpm in a stepped speed-up mode (simulating a flow rate of 0.5m / s to match the cleaning needs under low flow rates in the tropics), and the motor power is adapted to the limited power reserves of the research vessel.

[0058] Real-time monitoring of scraper torque changes; when the reading exceeds... Automatic overload protection is triggered at certain times (to prevent equipment jamming caused by stubborn tropical biofilms);

[0059] Once the research vessel leaves the mooring area and the water flow speed returns to 0.5 m / s, it automatically switches back to hydraulic drive mode and disconnects the motor to reduce energy consumption.

[0060] Field tests have verified that the device described in this embodiment can achieve a pipeline cleanliness rate of 99.7% under zero secondary pollution conditions in the tropical research vessel operating environment (30-32℃, high biological activity, environmentally sensitive), without requiring downtime maintenance. It is suitable for stable operation on tropical research vessels under long-term, low-flow-rate conditions, effectively reducing the risk of research operation interruptions caused by biological blockage.

[0061] Karman vortex street verification: When the research vessel is traveling at 0.5 m / s in the tropics for scientific research operations, the corresponding water flow velocity relative to the hull is 0.5 m / s. The water flows into the ballast water pipe 1 and drives the rotating scraper 5 to rotate. When the rotating scraper 5 rotates under the fluid drive, the centrifugal stripping effect generated by its rotation causes the sediments attached to the pipe wall to be stripped off the pipe wall by radial acceleration, thus avoiding the residue of tropical organisms.

[0062] Simultaneously, driven by the rotating scraper 5, the flow velocity of the water in the ballast water pipe increases, according to the Reynolds number calculation formula of the Karman vortex street: ,in, For fluid density, For flow rate, The feature size of the obstacle. For the fluid dynamic viscosity, taking the western Pacific Ocean as an example, with a fluid density of 1025 kg / m³, a flow velocity of 0.5 m / s, and an obstacle characteristic size of 0.3 m, the corresponding fluid dynamic viscosity in the western Pacific Ocean is 1 × 10⁻⁶. -3 Pa·s, The calculated value is 153750. At this point, 40 <Re<3×10 5 Symmetrical vortices begin to periodically detach, forming a regular Karman vortex street. The Karman vortex street generates high-frequency shear force on the wall of ballast water pipe 5, causing the tropical biological residues attached to ballast water pipe 1 to detach.

Claims

1. A method for operating a self-cleaning device for ballast water pipelines on a tropical research vessel, characterized in that: The self-cleaning device includes a ballast water pipe (1), a double rod fixing device (2) is set near one end of the ballast water pipe (1) along the direction of water flow perpendicular to the ballast water pipe (1), a screw (3) is inserted into a rotary bearing (4) located in the gap of the double rod fixing device (2) along the direction of water flow in the ballast water pipe (1), a rotary scraper (5) is set on the side of the screw (3) near the double rod fixing device (2), a silicon nitride ceramic shaft seal (6) is set on the contact side of the screw (3) passing through the rotary bearing (4) of the double rod fixing device (2), and the head of the screw (3) passing through the silicon nitride ceramic shaft seal (6) is exposed and forms a regular shaped end face; There is a gap of 0.1~0.3mm between the blade edge of the rotating scraper (5) and the pipe wall of the ballast water pipe (1); When the research vessel is traveling at low speed in the tropics to carry out scientific research operations, the water flows into the ballast water pipe (1) and drives the rotating scraper (5) to rotate. When the rotating scraper (5) rotates under the fluid drive, the centrifugal stripping effect generated by its rotation causes the sediments attached to the pipe wall to be stripped off the pipe wall by radial acceleration, thus avoiding the residue of tropical organisms. Simultaneously, driven by the rotating scraper, the flow velocity of the water in the ballast water pipe (1) increases, according to the Reynolds number calculation formula of the Karman vortex street: ,in, For fluid density, For flow rate, The feature size of the obstacle. Due to the fluid dynamic viscosity, the characteristics of tropical water bodies make... >40, the symmetrical vortex begins to periodically and alternately fall off, forming a regular Karman vortex street. The Karman vortex street forms a high-frequency shear force on the ballast water pipe wall, causing the tropical biological residues attached to the ballast water pipe (1) to fall off.

2. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 1, characterized in that: A pair of rotary dampers (7) are provided on both sides of the rotating scraper (5) on the screw (3) to prevent the rotating scraper (5) from axially displacing on the screw (3).

3. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 1, characterized in that: The rotary scraper (5) is a rotary scraper (5) made of metal alloy material.

4. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 3, characterized in that: The surface of the rotating scraper (5) is coated with an Al2O3-TiO2 coating.

5. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 1, characterized in that: The screw (3) and the double rod fixing device (2) are connected by a Ni80Cr20 transition layer (8) welded by electron beam, and the weld throat thickness is not less than 1 / 2 of the shaft diameter.

6. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 5, characterized in that: The double rod fixing device (2) and the rotating scraper (5) are joined by laser self-fusion welding to form a metallurgical bond on the wall of the rotary stopper (7) on the side of the double rod fixing device (2).

7. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 1, characterized in that: The double-rod fixing device (2) consists of a pair of fixing rods, with the two fixing rods arranged in parallel. The ends of the fixing rods are welded to the wall of the ballast water pipe (1).

8. The working method of the self-cleaning device for ballast water pipelines of a tropical research vessel according to claim 1, characterized in that: The double-rod fixing device (2) is installed near the inlet of the ballast water pipe (1).

Images