An air lubrication system for energy saving of VLCC

Abstract

The application relates to an air lubrication system for energy saving of a VLCC, belonging to the technical field of ship energy saving. The system comprises an air compressor unit, a control unit, a valve control unit, a bubble generator, a compressed air pipe, a Y-type shunt and a hydraulic valve, etc. The air compressor unit (1) is arranged in a compressor room (11), and the outlet of the air compressor unit (1) is connected with a compressed air pipe (5) provided with a hydraulic master valve (9). The system is arranged according to the principles of meeting the specifications, facilitating arrangement, saving pipe materials, uniform bubble spraying and high ship bottom coverage, etc. The system can ensure that a continuous and uniform air film is steadily generated between the bottom of the ship and the water body under different running conditions of the ship, energy consumption is reduced, sailing efficiency is improved, the system has wide application prospects and economic benefits, and further technical reserves are provided for the application of the novel energy saving technology.

Description

Technical Field

[0001] This utility model relates to an air lubrication drag reduction system for VLCC energy saving, which belongs to the technical field of marine energy saving. Background Technology

[0002] With the International Maritime Organization (IMO) continuously raising its requirements for energy conservation and emission reduction, reducing ship energy consumption has become a development trend in the shipbuilding industry. Currently, the energy-saving potential of conventional designs is gradually diminishing, necessitating the search for new and effective solutions to improve ship design energy efficiency. Air lubrication drag reduction technology, as a novel energy-saving technology, uses a bubble generator to produce micron-sized bubbles near the outer surface of the ship's bottom, forming a thin gas-liquid two-phase mixture. This reduces the fluid density and viscosity near the outer surface of the bottom plate and alters the flow structure within the turbulent boundary layer, effectively reducing ship resistance. Furthermore, its net energy-saving effect is significant, it greatly contributes to reducing EEDI (Extended Energy Efficiency Index), requires minimal modification to the ship type, and is cost-effective, thus gradually gaining attention both domestically and internationally. However, current data on the operation of air lubrication drag reduction is limited, and the ship types already applied are incomplete, with a lack of relevant layout design information. To address this issue, this utility model, based on the VLCC (Very Large Crude Carrier) ship type, presents an overall layout of the air lubrication drag reduction system, providing data sources and technical reserves for the future application of this novel energy-saving technology. Utility Model Content

[0003] To address the problems existing in the prior art, this utility model provides an air lubrication drag reduction system for improving the energy-saving effect of VLCCs. It mainly solves the problems of equipment layout and space utilization, as well as cost and equipment maintenance. By rationally arranging system equipment such as air supply devices, pipelines, and bubble generating devices, it makes full use of the limited space inside the ship, while taking into account the mutual influence and collaborative work between equipment. It improves the energy-saving effect of the ship without affecting other normal functions and operations.

[0004] The technical solution adopted in this utility model is as follows: an air lubrication drag reduction system for VLCC energy saving, wherein an air compressor unit is installed in the compressor room, and the outlet of the air compressor unit is connected to a compressed air pipe equipped with a hydraulic master valve. The compressed air pipe passes through the compressor room, the empty compartment, and the upper deck in sequence to enter the ballast tank. The compressed air pipe is divided into multiple groups of air lubrication drag reduction mechanisms through a Y-type diverter fitting. In the air lubrication drag reduction mechanism, the venting branch pipe is connected to the bubble generator, and a branch pipe hydraulic valve is installed on the venting branch pipe; the bubble generator is located at the bottom of the ship.

[0005] Furthermore, the air compressor unit comprises 11 air compressors, which are symmetrically distributed relative to the ship.

[0006] Furthermore, the system also includes a valve control unit and a control unit located in the cab. The control unit is electrically connected to the air compressor unit, and the valve control unit is electrically connected to the hydraulic main valve and the branch hydraulic valve.

[0007] Furthermore, the number of bubble generators is 22, evenly distributed within the bow 1 / 3 area, and symmetrically distributed on the port and starboard sides.

[0008] The beneficial effects of this invention are as follows: This invention is the first to propose an overall arrangement of an air lubrication drag reduction system based on VLCC hull type. This invention can reduce the sailing resistance of ships and reduce energy consumption. This invention fills the gap in the current overall arrangement scheme of bubble drag reduction systems for VLCC hull type, and can provide a technical foundation for the subsequent application of this bubble drag reduction system in VLCC hull type.

[0009] This invention studies the overall arrangement of a bubble drag reduction system based on VLCC hull design. By supplying microbubbles to the outer surface of the hull bottom, a thin layer of gas-liquid two-phase mixture is formed, reducing the resistance between the hull bottom and the water flow, thereby improving the energy-saving effect of the VLCC. Compared with traditional arrangements, this invention employs an optimized air supply pipeline layout, a specially designed bubble generator, and intelligent system control functions. It can adjust the air supply pressure and flow rate in real time according to the ship's navigation status and draft, ensuring optimal drag reduction performance. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an air-lubricated drag-reducing system for energy saving in VLCCs.

[0011] In the diagram: 1. Air compressor unit, 2. Control unit, 3. Valve control unit, 4. Bubble generator, 5. Compressed air pipe, 6. Y-type splitter pipe, 7. Branch hydraulic valve, 8. Release branch pipe, 9. Hydraulic main valve, 10. Cabin, 11. Air compressor room, 12. Empty compartment, 13. Upper deck, 14. Ballast tank. Detailed Implementation

[0012] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention, but are not limited thereto, unless otherwise stated.

[0013] The specific embodiments of this utility model are described in detail below with reference to the technical solution: This utility model discloses an air lubrication drag reduction system layout design for improving the energy-saving effect of VLCC, including an air compressor unit 1, a control unit 2, a valve control unit 3, a bubble generator 4, a compressed air pipe 5, a Y-type diverter pipe 6, a branch hydraulic valve 7, a venting branch pipe 8, and a hydraulic main valve 9.

[0014] The air compressor unit 1 is the air source device, providing the required pressure and flow rate of air for the air lubrication and drag reduction system; the control unit 2 has monitoring and control functions, used to monitor the performance parameters of the ship and the air lubrication system, control the key components of the air compressor unit, and ensure the effective operation of the entire system; the valve control unit 3 is used to remotely control the opening and closing of hydraulic valves; the bubble generator 4 is a device for generating drag-reducing bubbles that cover the bottom of the ship; the compressed air pipe 5 is used to deliver air from the air compressor unit to the bubble generator; the Y-type splitter pipe 6 is used to divide the main release pipe into multiple branch pipes; the opening and closing of the branch pipe hydraulic valve 7 controls the flow direction of compressed air, the release branch pipe 8 is connected to the bubble generator 4, and the branch pipe hydraulic valve 7 is installed on it; the hydraulic master valve 9 controls the on and off of compressed air in the compressed air pipe 5. Example 1

[0015] An air lubrication and drag reduction system for energy saving in VLCCs includes an air compressor unit 1 installed in a compressor room 11. The air compressor unit 1 comprises 11 air compressors, which are symmetrically distributed relative to the ship's interior.

[0016] The outlet of the air compressor unit 1 is connected to a compressed air pipe 5 equipped with a hydraulic master valve 9. The compressed air pipe 5 passes sequentially through the compressor chamber 11, the empty compartment 12, and the upper deck 13 before entering the ballast tank 14. The compressed air pipe 5 is divided into multiple groups of air lubrication and drag reduction mechanisms by a Y-shaped branch pipe fitting 6. In the air lubrication and drag reduction mechanism, the release branch pipe 8 is connected to the bubble generator 4, and a branch pipe hydraulic valve 7 is installed on the release branch pipe 8. The bubble generator 4 is located at the bottom of the ship. There are 22 bubble generators 4, evenly distributed in the bow 1 / 3 area, and symmetrically distributed on the port and starboard sides.

[0017] The system also includes a valve control unit 3 and a control unit 2 located in the driver's cab 10. The control unit 2 is electrically connected to the air compressor unit 1, and the valve control unit 3 is electrically connected to the main hydraulic valve 9 and the branch hydraulic valve 7. This layout comprehensively considers compliance with regulations, ease of layout, cost control, and improved layout effectiveness.

[0018] During ship navigation, the air compressor unit 1 is started, the control valve control unit 3 opens the corresponding hydraulic valve 7, and the compressed air is diverted through the compressed air pipe 5 to the release branch pipe and reaches the symmetrical bubble generator 4 arranged at the bottom of the ship to generate small bubbles with a diameter of micrometers. This forms a thin gas-liquid two-phase mixed flow on the outer surface of the ship bottom, reducing the fluid density and viscosity near the outer surface of the ship bottom and changing the flow structure within the turbulent boundary layer, so as to reduce the ship's navigation resistance. To minimize the impact on the ship's original structure and equipment ventilation, the original empty compartment at the bow was converted into an empty compartment plus an air compressor room. The air compressor room is used only to install the air source air compressors for the air lubrication and drag reduction system. The 11 air compressors are roughly symmetrical about the midships to ensure temperature balance and proper ventilation equipment placement. Control units and valve control units are located in the bridge for remote control by the crew. The number and location of bubble generators are closely related to the ship type. After discussion, it was determined that there are 22 of them, evenly distributed in about 1 / 3 of the bow area, symmetrically on both sides, without affecting the original bottom structure, and facilitating pipeline laying. To reduce the impact of pipelines penetrating the anti-collision bulkhead on the hull structure, compressed air pipes run from the air compressor room to the empty compartment, then to the upper deck, and, where feasible, as close as possible to the bubble generators to the ballast tanks, ensuring a stable supply of air to the bubble generators at the bottom of the ship. The arrangement of hydraulic valves is determined according to the pipeline routing requirements.

[0019] This invention proposes for the first time an integrated layout of an air lubrication drag reduction system for VLCC hull types. It can reduce the ship's sailing resistance and energy consumption. It fills the gap in current integrated layout schemes for bubble drag reduction systems in VLCC hull types and provides a technical foundation for the application of this bubble drag reduction system in subsequent VLCC hull types.

[0020] This invention studies the overall arrangement of a bubble drag reduction system based on VLCC hull design. By supplying microbubbles to the outer surface of the hull bottom, a thin layer of gas-liquid two-phase mixture is formed, reducing the resistance between the hull bottom and the water flow, thereby improving the energy-saving effect of the VLCC. Compared with traditional arrangements, this invention employs an optimized air supply pipeline layout, a specially designed bubble generator, and intelligent system control functions. Regarding the air lubrication drag reduction system, various layout schemes were discussed. Based on spatial feasibility, pipeline delivery efficiency, and internal pressure drop requirements, the length limit of the gas delivery pipeline was determined. Considering aesthetics and ease of maintenance, layout schemes for the gas source, pipelines, and bubble generator were proposed. Furthermore, by comparing the impact on the original hull structure, the complexity of the overall system installation, and the cost of various schemes, the layout scheme with minimal impact on the hull structure, simple modification, and lower cost was selected, optimized, and finally determined.

[0021] A bubble generator is a device used to generate ultrafine bubbles, mainly composed of a gas mixing chamber, compressed air pipeline connectors, and a flying wing. It is installed in the forward area of ​​the hull through an opening. When the ship moves forward, driving air passes through the mixing chamber of the bubble generator into the water. Applying the Kelvin-Helmholtz instability (KHI) physics phenomenon, ultrafine bubbles are generated and immediately released. These microbubbles remain in the water for a long time, forming a microbubble cloud, reducing the direct contact area between the hull and the water, thereby reducing the ship's drag.

[0022] When changes occur in the ship's navigation status, draft, etc., the valve control panel, which is linked in real time with the ship's draft speed meter, automatically adjusts the valve opening based on changes in electrical signals and records flow data through flow meters on the pipeline. The air compressor controller, also linked to the valve control panel, adjusts the air compressor outlet pressure and displays and records it digitally. In other words, based on the ship's navigation status and draft, the valve control panel and air compressor controller in the wheelhouse adjust and control the air supply pressure and flow in the pipeline in real time to ensure optimal drag reduction.

[0023] The above embodiments are only used to illustrate the present utility model. Any equivalent transformations and improvements made on the basis of the technical solution of the present utility model shall not be excluded from the protection scope of the present utility model.

Claims

1. An air-lubricated drag-reducing system for energy saving in VLCCs, characterized in that, The air compressor unit (1) is installed in the compressor room (11). The outlet of the air compressor unit (1) is connected to the compressed air pipe (5) with the hydraulic main valve (9). The compressed air pipe (5) passes through the compressor room (11), the empty compartment (12), and the upper deck (13) in sequence and enters the ballast tank (14). The compressed air pipe (5) is divided into multiple groups of air lubrication drag reduction mechanisms through the Y-type diverter fitting (6). In the air lubrication drag reduction mechanism, the gas release branch pipe (8) is connected to the bubble generator (4), and a branch pipe hydraulic valve (7) is installed on the gas release branch pipe (8); the bubble generator (4) is installed at the bottom of the ship.

2. The air lubrication drag reduction system for VLCC energy saving according to claim 1, characterized in that: The air compressor unit (1) includes 11 air compressors, which are symmetrically distributed in relation to the ship.

3. The air lubrication drag reduction system for VLCC energy saving according to claim 1, characterized in that: The system also includes a valve control unit (3) and a control unit (2) located in the cab (10). The control unit (2) is electrically connected to the air compressor unit (1), and the valve control unit (3) is electrically connected to the hydraulic main valve (9) and the branch hydraulic valve (7).

4. The air lubrication drag reduction system for VLCC energy saving according to claim 1, characterized in that: The number of bubble generators (4) is 22, which are evenly distributed in the 1 / 3 area of ​​the bow and symmetrically distributed on the port and starboard sides.

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