JPH11310188A - Device for reducing friction resistance of ship - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the closure of an air spitting part due to the clinging of marine animals and vegetables. SOLUTION: A compressor 11 is connected via an air feed pipe 12 to an air blow-off device 3 placed on a bottom plate 2. The air feed pipe 12 is provided with an ejector 17. A chloride gas generator 18, in which an anode 29 and a cathode 30 connected to a dc power supply 28 are provided within an electrolytic vessel 22, is installed on a hull 1. A water feed pipe 23 having a seawater pump 24 and an overflow pipe 26 are connected to the electrolytic vessel 22 to change seawater 20. The section 22a of the electrolytic vessel 22 in which the anode 29 is present is connected to the ejector 17 via a chloride gas pipe 21. Chloride gas 19 generated by the electrolysis of the seawater 20 is mixed into pressurized air 14 fed to the air blow-off device 3 from the compressor 11, and is spit out of the air blow-off device 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reducing frictional resistance of a ship for reducing frictional resistance acting on a hull surface during navigation, and more particularly to an air blower for generating microbubbles. The present invention relates to a device for reducing frictional resistance of a ship which can suppress the accumulation of marine organisms.

[0002]

2. Description of the Related Art During the navigation of a ship, a boundary layer of seawater is formed around the hull due to the viscosity of seawater as a fluid. In this boundary layer, the flow velocity of the seawater is zero and the hull surface is zero. It tends to change drastically as the distance from the surface increases, and seawater frictional resistance acts on the surface of the hull, which is one of the major factors of hull resistance.

[0003] Therefore, in recent years, studies have been made to improve the propulsion performance by reducing the frictional resistance acting on the surface of the hull, and as one of the measures, micro-bubbles (micro-bubbles) are generated from the hull surface. And blow the microbubbles into the boundary layer of the submerged part (submerged part) of the hull to cover the submerged surface of the hull with the microbubbles, thereby reducing the frictional resistance acting on the hull surface. Research on the microbubble propulsion method is ongoing.

As one means for realizing the microbubble propulsion method, as shown in FIG. 3 (a) and (b), an example of the outline thereof is shown in FIG. An air reservoir 4 is formed by attaching a perforated plate 6 having blowout ports (pores) 7 at a required pitch by bolts 8 to form an air blowout portion 4 and surrounding the air blowout portion 4. A number of air blowers 3 which are constructed by attaching water-tight 9 to the inside of the bottom shell 2 are arranged at required positions on the bow bottom 1a of the hull 1 and each of the air blowers 3 The electric motor 10 installed on the deck
A compressor 11 as an air supply device driven by a compressor is connected via an air supply pipe 12 provided with a shut-off valve 13, and the compressed air 14 generated by the compressor 11 is blown out by an air blower. 3, a frictional resistance reducing device is proposed in which the pressurized air 14 is blown out into the water from the air blowing portion 4 of the air blowing device 3 to cover the bottom surface of the hull 1 with the generated microbubbles. Have been. Reference numeral 15 denotes an intake pipe provided with an intake port 16 at the tip for guiding air to the compressor 11.

[0005]

However, since the air blowing portion 4 of the air blowing device 3 is installed at the bottom of the ship, that is, at the submerged portion of the hull 1, when the ship is anchored at a port, etc. Since the pressurized air 14 is not blown out from the air blowout unit 4, seawater may enter the air blower 3 from the air blowout port 7, and marine organisms such as shellfish and algae may be blown out by the air blower. It is conceivable that the air blowing portion 4 adheres to and accumulates on the inner surface of the inside 3 and closes the air blowing portion 4. Therefore, a problem arises in that marine organisms attached to the air blower 3 must be periodically scraped and removed.

Therefore, the present invention provides a state in which marine organisms are repelled by blowing chlorine gas into the air blower without scraping marine organisms attached to the air blower. The purpose is to suppress the adhesion and accumulation and prevent the air blowing portion from being closed.

It is conceivable that a chlorine gas cylinder is mounted on a ship in advance and the chlorine gas is led to the air blower 3, but in this case, a large number of chlorine gas cylinders must be mounted.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an air blower for blowing out pressurized air at a required position on a hull outer panel, and an air blower for surrounding the air blower. A large number of air blowers each including an air reservoir casing attached to the inside of the hull outer panel are provided, and an air feeder is connected to the air blowers via an air feed pipe provided with a shutoff valve. In a device for reducing frictional resistance of a ship in which micro-bubbles are generated by blowing pressurized air generated by a feeder into water through an air blower, the above-mentioned air-supply pipe is provided at an intermediate position. A mixer for mixing chlorine gas into compressed air is provided, and a chlorine gas generator for electrolyzing seawater to generate chlorine gas is connected to the mixer.

[0009] Chlorine gas generated by electrolysis of seawater in a chlorine gas generator is led to a mixer,
In the mixer, it is mixed with the pressurized air generated by the air supply device and supplied to the air blower. Therefore, chlorine is contained in the pressurized air led to the air blower, and this chlorine causes marine organisms to adhere, grow and grow inside the air blower and in the air blowout portion.
The extension can be prevented in advance.

Further, a chlorine concentration sensor for measuring the chlorine concentration in the pressurized air guided to the air blower is provided in the air supply pipe located downstream of the mixer, and the chlorine concentration sensor measures the chlorine concentration. Concentration of chlorine gas guided to the air blower by providing a control device for controlling the electrolysis of seawater in the chlorine gas generator to stop when the chlorine concentration exceeds the set value Can be controlled, the chlorine concentration in the pressurized air is controlled so as not to exceed a predetermined value, excess chlorine reacts with moisture to produce a liquid having oxidizing power, It is possible to reduce a possibility of adversely affecting the hull such as corrosion.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the apparatus for reducing frictional resistance of a ship according to the present invention. As shown in FIGS. 3 (a) and 3 (b), a required position of a bow bottom 1a of a hull 1 is shown. An air blowing section 4 and an air reservoir casing 9
And a compressor 11 driven by a motor 10 is connected to each air blower 3 via an air supply pipe 12 to reduce the frictional resistance of a ship. An ejector 17 as a mixer for mixing chlorine gas 19 into the pressurized air 14 guided to the air blower 3 is provided at an intermediate position of the air supply pipe 12.
Further, a chlorine gas generator 18 for electrolyzing seawater 20 to generate chlorine gas 19 is connected via a chlorine gas pipe 21.

The chlorine gas generator 18 is provided with a seawater pump 24 on the lower part of one side of a box-shaped electrolysis tank 22 in which two sections 22a and 22b are divided so that only the lower part communicates. An upper end of a water supply pipe 23 having a lower end connected to an intake 25 provided at the bottom of the ship is connected, and an overflow pipe 26 communicating with a drain 27 provided at the bottom of the ship is connected to the upper part of the other side of the electrolysis tank 22. Then, a certain amount of seawater 20 is stored in the electrolysis tank 22, and the seawater 20 in the electrolysis tank 22 is sequentially replaced by driving the seawater pump 24. Two electrodes, an anode 29 and a cathode 30, are provided in each of the divided sections 22a and 22b, and a DC power supply 28 is connected between the electrodes. The chlorine gas pipe 21 is connected to the upper end of the anode 29 side section 22a of the electrolysis tank 22, and the generated chlorine gas 19 is guided to the ejector 17. It is like that. The hydrogen gas 31 generated at the cathode 30 during the electrolysis of the seawater 20 is supplied to the cathode 3
The air is purged to the atmosphere through a purge pipe 32 connected to the upper end of the 0-side section 22b.

Further, the motor 10 for driving the compressor 11, the DC power supply 28 of the chlorine gas generator 18, and the seawater pump 24 of the water supply pipe 23 are started and stopped synchronously. The other components are the same as those shown in FIG. 3, and the same components are denoted by the same reference numerals.

When the compressor 11 is driven by the drive of the electric motor 10 during the navigation of the ship, the compressor 11
The pressurized air 14 generated by the air blower 4 is guided to each air blower 3 through the air supply pipe 12,
Blows out into the water to generate microbubbles. At this time, since the DC power supply 28 of the chlorine gas generator 18 is started in synchronization with the driving of the electric motor 10, the seawater 20 is electrolyzed in the electrolysis tank 22, and the anode 29 side Chlorine gas 19 is generated in the section 22a. The generated chlorine gas 19 is supplied to the ejector 17 provided in the air supply pipe 12 by the pressurized air 14.
The pressurized air 1 guided to the ejector 17 through the chlorine gas pipe 21 by the suction force generated when the air passes through the air blower 3 in the ejector 17
4 will be mixed. At this time, since the seawater pump 24 is also driven in synchronization with the drive of the electric motor 10, the seawater 20 in the electrolysis tank 22 is sequentially replaced, so that the chlorine ion in the seawater 20 in the electrolysis tank 22 is changed. Since the concentration can be maintained at a high level, the chlorine gas 19 having a high concentration can be continuously generated.

Therefore, the compressed air 14 containing chlorine having a high concentration is always supplied from the air blowing section 4 of the air blowing device 3.
The marine organisms that enter the air blower 3 together with the seawater through the air blower 4 at the time of berth due to the chlorine are blown out by the chlorine.
Can be prevented from adhering, growing, and extending to the inside of the inside or the air blowing portion 4. Therefore, no marine organisms accumulate in the air blower 3 and the air blower 3
Can be maintenance-free without the need for marine organism scraping work requiring a great deal of labor.
Further, since the chlorine gas 19 which is mixed with the pressurized air 14 and guided to the air blowing device 3 is obtained by returning seawater to seawater, there is no concern about environmental pollution.

FIG. 2 shows another embodiment of the present invention. In the same construction as shown in FIG. 1, an air blower 3 is provided at a position downstream of the ejector 17 of the air supply pipe 12. A chlorine concentration sensor 33 for measuring the concentration of chlorine in the pressurized air 14 guided to the compressor, and the value of the chlorine concentration in the pressurized air 14 measured by the chlorine concentration sensor 33 becomes higher than a predetermined set value. At this time, the DC power supply 28 and the seawater pump 24 of the chlorine gas generator 18 are stopped, and thereafter, when the value of the chlorine concentration falls below a predetermined set value, the DC power supply 28 and the seawater pump 24 are activated again. Control device 34 is provided. In addition, the same components as those in FIG. 1 are denoted by the same reference numerals.

According to the present embodiment, the air blower 3
The chlorine concentration in the pressurized air 14 guided to the air can be suppressed to a predetermined value or less, and the excess chlorine reacts with moisture to become a liquid having an oxidizing power, and adversely affects the hull 1 such as corrosion. It is possible to suppress the possibility of occurrence.

It should be noted that the present invention is not limited to only the above embodiment, and that the electrolysis tank 22 of the chlorine gas generator 18 may have any shape.
Further, if the seawater 20 can be forcibly discharged, it may be disposed at an arbitrary position.
If it is a submerged part, it may be arranged on the ship side etc. other than the ship bottom. Further, as a mixer other than the ejector 17,
It is preferable that the chlorine gas 19 is forcibly mixed into the pressurized air 14, and the activation and stop of the electric motor 10, the DC power supply 28, and the seawater pump 24 are desirably synchronized. Of course, various modifications can be made without departing from the spirit of the present invention.

[0020]

As described above, according to the present invention, the following excellent effects are exhibited. (1) At a required position on the hull outer panel, there are provided a number of air blowers each including an air blowing section for blowing pressurized air and an air reservoir casing attached to the inside of the hull outer panel so as to surround the air blowing section. The air blower is connected to an air blower via an air blower equipped with a shut-off valve, and the pressurized air generated by the air blower is blown into water through the air blower. In the apparatus for reducing frictional resistance of a marine vessel in which micro bubbles are generated by performing the mixing, a mixer for mixing chlorine gas into the pressurized air is provided at an intermediate position of the air supply pipe; The vessel is connected to a chlorine gas generator for electrolyzing seawater to generate chlorine gas, so the chlorine gas generated by seawater electrolysis is mixed into the pressurized air. By being able to blow out from the air blower, it is possible to prevent marine organisms from adhering, growing and extending inside the air blower and the air blowout portion, and to prevent the air blowout portion from being blocked.
Therefore, the air blower can be made maintenance-free and does not require a scraping operation for removing marine organisms. (2) Since chlorine gas can be produced indefinitely by electrolysis of seawater, the cost of producing chlorine gas is low, and chlorine gas obtained from seawater is returned to seawater. No risk of contamination. (3) A chlorine concentration sensor for measuring the chlorine concentration in the pressurized air guided to the air blower is provided on the air supply pipe located downstream of the mixer, and the chlorine concentration measured by the chlorine concentration sensor is provided. The control unit for controlling to stop the electrolysis of seawater in the chlorine gas generator when exceeds the set value, the chlorine concentration in the pressurized air is less than a predetermined value The excess chlorine gas reacts with the moisture to produce an oxidizing liquid,
The possibility of adverse effects such as corrosion on the hull can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional side view showing an embodiment of a frictional resistance reducing device for a ship according to the present invention.

FIG. 2 is a schematic sectional side view showing another embodiment of the present invention.

FIG. 3 shows an example of a device for reducing frictional resistance of a ship that has been proposed so far, in which (a) is a schematic cut-away side view,
(B) is an enlarged cut side view of the air blowing device.

[Explanation of symbols]

 2 Ship bottom shell (hull shell) 3 Air blower 4 Air blower 9 Air reservoir casing 11 Compressor (air feeder) 12 Air feed pipe 13 Shut off valve 14 Pressurized air 17 Ejector (Mixer) 18 Chlorine gas Generator 19 Chlorine gas 20 Seawater 21 Chlorine gas pipe 33 Chlorine concentration sensor 34 Controller

Claims (2)

[Claims] 1. An air blower comprising: an air blower for blowing pressurized air at a required position on a hull outer panel; and an air reservoir casing attached to the inside of the hull outer panel so as to surround the air blower. Are connected to the air blower through an air feed pipe equipped with a shut-off valve, and pressurized air generated by the air blower is submerged through the air blower. In the frictional resistance reduction device of a ship which is configured to generate micro bubbles by blowing out, a mixer for mixing chlorine gas into the pressurized air is provided at an intermediate position of the air supply pipe, and An apparatus for reducing frictional resistance of a ship, comprising a structure in which a chlorine gas generator for generating chlorine gas by electrolyzing seawater is connected to the mixer. 2. A chlorine concentration sensor for measuring a chlorine concentration in pressurized air guided to an air blower is provided in an air supply pipe located downstream of the mixer, and the chlorine concentration sensor measures the chlorine concentration. 2. The ship frictional resistance reducing device according to claim 1, further comprising a control device for controlling so as to stop the electrolysis of seawater in the chlorine gas generator when the chlorine concentration exceeds a set value.