Foam Lubrication System

Abstract

To provide a foam lubrication system that effectively utilizes water used on ships and achieves more efficient energy savings by reducing friction. [Solution] This is a foam lubrication system that pressurizes secondary cooling water for ship engines and supplies it from the nozzle of an eductor 12, and sprays the aerated cooling water sucked in by the Bernoulli effect along the bottom surface of the ship's bottom. Instead of secondary cooling water, liquids that can be reused on ships, such as ballast water and general service water, can be used. Pressurized water supplied from a ship 10 is sprayed from the eductor's diffuser from the ship's bottom on the bow side toward the stern, forming an air lubrication layer between the ship's bottom and the water. Unlike a blower that requires so-called driving force, an eductor can spray aerated pressurized water using the supplied pressurized water. It is useful as an energy-saving or CO2-reducing technology.

Description

[Technical field]

[0001] This invention relates to a foam lubrication system, more specifically to a foam (air) lubrication system for ships that uses the water inside the ship to spray pressurized water containing air from the bottom of the ship, forming an air lubrication layer between the surface of the bottom of the ship and the seawater. [Background technology]

[0002] Conventional marine air lubrication systems are known from the following patent documents: This is a friction resistance reduction device for an air-lubricated ship that reduces the friction resistance between the hull and the surrounding water by spraying air around the hull. High-pressure air is supplied to the ejector body, which draws in low-pressure air, and the high-pressure and low-pressure air are sprayed from the ejector body to generate air bubbles around the hull. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-193642 A DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] However, this frictional resistance reduction device for an air-lubricated ship sucks in low-pressure air when the ejector discharges high-pressure air, and then simultaneously discharges the high-pressure air and the low-pressure air from the bottom of the ship. As a result, the air is sprayed into seawater, which tends to have insufficient affinity with seawater. For example, the shear force of seawater does not act sufficiently on the sprayed air, and a certain air lubrication layer cannot necessarily be formed between the bottom of the ship and the water.

[0005] As a result of extensive research, the inventor discovered that all of the above-mentioned problems could be solved by supplying the water present on the ship as pressurized water to the eductor, mixing the pressurized water with air, and spraying it out, thereby forming an air lubrication layer and making effective use of, for example, the secondary cooling water of the engine, and thus completing this invention.

[0006] In other words, the purpose of this invention is to effectively form an air lubrication layer by spraying pressurized water containing bubbles using water used or present on the ship, thereby making effective use of the water used on the ship and general service water, and to construct an efficient foam lubrication system. [Means for solving the problem]

[0007] The invention described in claim 1 is a foam lubrication system in which pressurized water supplied from a ship is supplied to an eductor installed on the bottom of the ship on the bow side, and when it is discharged from the nozzle, air is sucked in from the outside due to the Venturi effect, and water containing bubbles is discharged from the diffuser from the bottom of the ship on the bow side toward the stern, thereby forming an air lubrication layer containing air bubbles between the bottom of the ship and the water. Here, the eductor supplies a high-speed fluid from a supply port formed in its housing body, draws in air at low pressure in the nozzle by the Venturi effect, and ejects the fluid mixed with the air from the diffuser at a medium speed from the discharge port. The fluid supplied in this case is a liquid, but the concept also includes steam (gas). In addition, the pressurized water supplied from the ship includes water that has been used on the ship, such as secondary engine cooling water, ballast water, and general service water, which is pumped to the bow side and supplied to the eductor. Note that these types of water can also be switched and supplied.

[0008] The invention described in claim 2 is a foam lubrication system described in claim 1, wherein the pressurized water includes any of secondary cooling water for the ship's engine, ballast water for the ship, and general service water. The secondary engine cooling water includes seawater supplied to a heat exchanger (such as a plate cooler) that circulates the cooling water for the diesel engine. In the case of an electric motor-driven ship that does not have an engine, the ballast water or utility water is supplied as pressurized water to the eductor. This eductor is a device (a concept that includes the above-mentioned ejector) that uses a high-pressure fluid rather than a mechanical drive such as a pump to suck in low-pressure air and eject it at medium pressure.

[0009] As described above, by forming a certain air lubrication layer between the ship's bottom shell and seawater, friction caused by seawater during navigation can be reduced. In this case, by utilizing water that is not effectively used by the ship, it is possible to reduce costs for the equipment. Effect of the Invention

[0010] According to the inventions described in claims 1 and 2, the water used on the ship and general service water can be reused, and this water can be effectively used to form an air lubrication layer. This contributes to reducing carbon dioxide (CO2) emissions and contributes to reducing the operating costs of the ship. Furthermore, since no blower or the like is used for this air blowing, the above effects can be further enhanced. This device can be applied to ships equipped with diesel engines, ships driven by electric motors, hybrid ships, etc. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a foam lubrication system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing a schematic diagram of an eductor portion according to the first embodiment of the present invention. [Diagram 3] FIG. 2 is a cross-sectional view showing an eductor portion according to the first embodiment of the present invention. [Figure 4] FIG. 1 is a longitudinal cross-sectional view showing a schematic view of a foam lubrication system according to a second embodiment of the present invention. [Diagram 5]FIG. 11 is a schematic diagram showing a ship's hull cut in half in a foam lubrication system according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0013] 1 to 3 are schematic diagrams for explaining the general configuration of a foam (air) lubrication system according to a first embodiment of the present invention. In this embodiment, secondary cooling water for a main engine (diesel engine) 11 arranged on the stern side of a ship 10 is supplied via piping 13 to a pair of eductors 12 arranged on the bottom of the ship on the bow side. The secondary cooling water is seawater taken in from a seawater intake (sea chest) 14 and supplied to a cooling water heat exchanger (plate cooler) 15 for engine cooling water. Reference numeral 16 denotes a cooling seawater pump. A part of this seawater (secondary cooling water) is pressurized from the cooling seawater pump 16 and also from the cooling water heat exchanger 15 and fed to the pair of eductors 12 via the above-mentioned piping 13. Seawater taken in from another seawater intake 14B is similarly supplied as pressurized water by a bilge pump 17 also used for firefighting and a utility water pump 18 also used for firefighting through piping 13 to a pair of left and right eductors 12 on the bow side. The secondary cooling water is discharged from the eductors 12 through a discharge port 21 on the bottom of the vessel toward the stern.

[0014] Here, the configuration of the eductor 12 will be described with reference to FIGS. As shown in Fig. 3, the basic eductor structure is such that an inlet 23 for the secondary cooling water (pressurized water) and its passage, a tapered nozzle 24 at the end of the passage, and a discharge port 25 communicating with the discharge port 21 are arranged coaxially in an eductor main body (body) 22. The pressurized water flowing in from the inlet 23 is narrowed by the nozzle 24 to a high speed, and flows into a diffuser 27 through a gap 26 around the nozzle. At this time, air is sucked in from an air suction port 28 provided to open into the gap 26 of the body 22 by the Venturi effect, and the secondary cooling water containing air is sprayed out from the discharge port 25 of the diffuser 27 at a predetermined speed (slower than the nozzle discharge speed).

[0015] FIG. 2 shows an example in which three eductors 12 (12A, 12B, 12C) are provided for each single vessel bottom discharge port 21. Secondary cooling water is supplied to each eductor 12 (12A, 12B, 12C), and three-way air introduction pipes 31 (31A, 31B, 31C) that open into the gaps of each eductor (12A, 12B, 12C) are connected in communication with each other. The discharge ports of the three eductors (12A, 12B, 12C) eject aerated pressurized water from the vessel bottom discharge port 21 along the outer plate of the vessel bottom, that is, in parallel with the flat vessel bottom toward the stern. That is, the aerated ejected water is ejected from each pair of left and right eductors 12 so as to be diffused in three directions (six directions in total) that branch out in a horizontal plane. Thus, a layer of air of a specified thickness and width, i.e., an air lubrication layer, is formed by the aerated water jetted from the bottom of the ship on the bow side. In this case, the water jetted from each eductor (12A, 12B, 12C) can be controlled in time, thereby controlling the amount of air jetted and the thickness of the air lubrication layer generated between the ship's bottom shell and the seawater. For example, a large amount of air is required in accordance with the ship's speed, i.e., when the ship is traveling at high speed, and a smaller amount of air is required at slow speeds. This reduces the frictional resistance of seawater. This control can be achieved by known means such as opening and closing valves.

[0016] FIG. 4 shows a second embodiment in which ballast water is used as the pressurized water. The eductor (ejector) 12 in this embodiment 2 is disposed on the ship bottom (deep tank) on the bow side, as in the above embodiment 1. Ballast water is supplied to the eductor 12 by a pump, and external air supplied from the air vent pipe head to the air introduction pipe 31 is supplied to the space around the nozzle of the eductor 12 and ejected at a predetermined speed from the discharge port 25 along the outer bottom shell of the ship at a predetermined speed. In other words, an air lubrication layer containing air bubbles is formed. Note that ballast water can be supplied from multiple ballast tanks. The other configurations are almost the same as those in the first embodiment.

[0017] Example 3 is presented for FIG. As shown in this figure, the eductor, which is located on the bow side, for example in the thruster room or deep tank, is configured to receive pressurized water at a predetermined pressure from a firefighting combined bilge water pump and / or a firefighting combined utility water pump, and to supply pressurized water containing air between the bottom shell and seawater by sucking air into the nozzle. The pressurized water is supplied to the eductor from the left and right pump water lines. Since the water ejected from the eductor contains air, an air lubrication layer is formed on the bottom of the ship in the same manner as described above, thereby reducing the frictional resistance of seawater. The eductor and other components of the device are the same as those in the above embodiment.

[0018] Thus, the present invention is a system for providing an air lubrication layer between a generally flat basin of a vessel's hull and water flowing beneath the basin while the vessel is moving across the water. The system introduces air into a basin outlet recess such that the water level within the recess is maintained substantially flush with the exterior surface of the basin. As the vessel moves forward across the water, the air within the recess mixes with the water at the air-water interface such that the air exits the recess to form an air-water mixture that forms a lubrication layer along a portion of the basin downstream of the recess. In this case, the air space injected reduces friction between the hull and the surrounding water, which reduces resistance and therefore requires less fuel, reducing costs and CO2 emissions. In addition, the direction of the water current containing bubbles can be freely controlled, making this system fully adaptable to slender vessels. This device is even more effective when installed as a permanent facility on a module carrier. Module carriers have a wide deck area in both length and width to accommodate large structures, and have a shallow draft and a large flat area on the bottom of the ship. Therefore, the bottom of the ship is easily covered with air bubbles, and air lubrication is expected to have a significant energy-saving effect. [Industrial Applicability]

[0019] This invention is useful as a technology relating to a foam lubrication system for ships or a friction reduction device using the same. [Explanation of symbols]

[0020] 12 (12A, 12B, 12C) Eductor, 15 Plate cooler, 21 Bottom discharge port; 23 secondary cooling water inlet, 24 nozzles, 27 Diffuser, 28 Air intake.

Claims

1. A foam lubrication system in which pressurized water supplied from a ship is supplied to an eductor installed on the bottom of the ship on the bow side and discharged from a nozzle, which draws in air from the outside due to the Venturi effect, and then blows aerated water out of the diffuser from the bottom of the ship on the bow side toward the stern, creating an air lubrication layer containing air bubbles between the bottom of the ship and the water.

2. The foam lubrication system of claim 1 , wherein the pressurized water includes any one of secondary cooling water for a ship's engine, ballast water for the ship, and utility water.

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