JP2011011699A - Microscopic bubble generator in hull - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microscopic bubble generator in a hull, which thickly forms microscopic bubbles, generated from a diffuser pipe, on a submerged surface of the hull, thereby reducing fluid friction resistance to save energy during operation of a ship.SOLUTION: The microscopic bubble generator in the hull 71, which discharges bubbles to the submerged surface 71c of the hull from a number of discharge ports arranged in the submerged surface to reduce the friction resistance of the hull, is equipped with: a multistage Roots blower 3 in which a pair of three-lobe Roots rotors stored in a blower casing is freely rotatably disposed by a drive motor 30, an outlet pipe 35 connected on the side of a discharge port thereof, and a diffuser pipe unit 45 connected to the distal end of a branch pipe 38 branched from the outlet pipe 35 via a header 37. The microscopic bubble generator supplies the diffuser pipe unit 45 with air sucked from outside as the Roots blower 3 runs, thereby generating a large amount of microscopic bubbles from a diffuser pipe body to thickly form the microscopic bubbles on the submerged surface 71c of the hull 71.

Description

  The present invention relates to a fine bubble generating device in a hull that reduces the frictional resistance of the hull by discharging bubbles from a number of diffuser tubes arranged on the submerged surface of the hull to the submerged surface.

  In order to reduce the fluid frictional resistance of the hull during navigation of the ship, the following patent document etc. proposes a technique for forming fine air bubbles (micro bubbles) on the submerged surface of the hull to form an air film / air layer. ing. In general, fine bubbles often disappear at a distance of several meters from the discharge port provided on the hull surface, and as the bubbles move gradually toward the stern side, the bubbles gradually increase while repeating coalescence. Detachment becomes faster and the effect of reducing fluid frictional resistance is reduced.

  In Patent Document 1, for the purpose of reducing the fluid frictional resistance of a ship or the like, a plurality of nozzles are arranged at predetermined intervals on the submerged surface of the hull, and the nozzles are arranged along the surface of the film body having fine irregularities. A method of supplying air is disclosed.

  In Patent Document 2, a jet outlet for jetting pressurized gas into the water is arranged on the submerged surface of the hull, and the inner wall of the jet outlet and the submerged surface are gently connected to the downstream position of the jet outlet. A microbubble generator having a surface is disclosed.

  In Patent Document 3, a negative pressure forming portion provided on a submerged surface of a hull, a shallow concave portion and a deep concave portion arranged at the front and rear of the negative pressure forming portion, and a passage for supplying pressurized air to the deep concave portion at the rear A frictional resistance reduction ship provided with is disclosed.

  However, in the method in which only pressurized air or pressurized gas (gas generated by combustion) as described in the above-mentioned document is ejected from the discharge port arranged on the submerged surface of the hull, bubbles are easily separated from the hull. Friction resistance is hard to decrease. For this reason, in order to supply a large amount of air, it is necessary to install a large compressor, and there is a problem that the equipment cost becomes high and it is difficult to save energy.

Japanese Patent No. 2890340 JP-A-9-150785 Japanese Patent Laid-Open No. 2002-2582

  An object of the present invention is to provide a fine bubble generating device in a hull that reduces the fluid frictional resistance by forming fine bubbles generated from a diffuser tube thickly on the submerged surface of the hull, thereby saving energy during ship operation. It is in.

In order to achieve the above object, an invention according to claim 1 is provided in a hull that reduces the frictional resistance of the hull by discharging bubbles to the submerged surface from a number of discharge ports arranged on the submerged surface of the hull. A microbubble generator,
A single-stage or multi-stage roots blower in which a pair of three-leaf root rotors housed in a blower casing provided with a suction port and a discharge port are rotatably provided by a drive motor, and a discharge pipe connected to the discharge port side; A diffuser pipe connected to the tip of the discharge pipe forming the discharge port,
A large amount of fine bubbles are generated from the diffuser by supplying air sucked from the outside by the operation of the Roots blower, and the fine bubbles are formed thickly on the submerged surface of the hull. It is characterized by.

  In order to achieve the same object, the invention described in claim 2 is the apparatus for generating fine bubbles in a hull according to claim 1, wherein a header is interposed in the discharge pipe, and a branch pipe connected to the header An air diffusion tube is provided at the tip.

  In order to achieve the same object, the invention described in claim 3 is the microbubble generator for a hull according to claim 1 or 2, wherein the space between the tip of the discharge pipe or the branch pipe and the diffuser pipe This is characterized in that a nozzle with a check valve is provided.

(Invention of Claim 1)
This fine bubble generating device in the hull generates a large amount of fine bubbles from the diffuser pipe by supplying air sucked from the outside by the operation of the roots blower, and the fine bubbles are thickened on the submerged surface of the hull. The formation reduces the frictional resistance of the hull and contributes to energy saving during ship operation.

(Invention of Claim 2)
Since the fine bubble generating device in the hull is provided so as to be branched and connected from the header interposed on the discharge side of the Roots blower to the discharge port, it is easy to perform maintenance and inspection work on the piping.

(Invention of Claim 3)
Since the fine bubble generating device in this hull has a nozzle with a check valve provided between the tip of the discharge pipe or the branch pipe and the diffuser pipe, the generation of fine bubbles is promoted. Furthermore, when the operation of the Roots blower is stopped, it is possible to prevent seawater or river water outside the ship from flowing back to the branch pipe side by the nozzle with a check valve.

External view of a ship to which the device of the present invention is applied Same vertical section of the ship Roots blower vertical side view Roots blower vertical front view Explanatory drawing of diffuser unit Enlarged view of nozzle part with check valve Explanatory drawing of the diffuser unit of another aspect Schematic diagram explaining the action of the diffuser

  The best mode of the present invention will be described below with reference to the drawings.

The fine bubble generating device B in the hull according to the present invention emits bubbles from a number of air diffuser units 45 arranged on the submerged surface 71c of the hull 71 of the ship 70 such as a tanker shown in FIG. 1 to the submerged surface 71c. Thus, the frictional resistance of the hull 71 is reduced, and the multistage roots blower 3 and various pipes related to the apparatus B are arranged in the hull 71 (FIG. 2).
Below, the fine bubble generator B in the hull which concerns on this invention is demonstrated in detail.

  As shown in FIG. 2, the machine base 1 of the microbubble generator B in the hull is arranged on a floor member 72 provided in the hull 71, and the multistage roots blower 3, the drive motor 30, Is installed.

  As shown in FIG. 3, the multistage roots blower 3 has two three-leaf root rotors 15 arranged vertically in a blower casing 4 provided with a suction port 5 and a discharge port 6. As shown in FIG. 4, the rotor shafts 16, 16 of the three-leaf root rotor 15 are rotatably provided by bearings 9, 11 attached to housings 8, 10 fixed to open ends on both sides of the blower casing 4, respectively. Yes. Timing gears 18 and 18 are fixed to one end 16a of each rotor shaft 16 so that the timing gears 18 and 18 are engaged with each other. A gear cover 19 is attached to the housing 10 so as to cover the timing gears 18 and 18. A pulley 20 is attached to the other end 16 b protruding from the housing 8 of the lower rotor shaft 16.

  A silencer 22 is attached to the suction port 5 via a suction pipe 21. A discharge pipe 24 to which a safety valve 25 for releasing the pressure air to the outside at the time of a sudden pressure increase is attached to the discharge port 6. Further, the pulley 20 is provided to be rotationally driven by the drive motor device 30 via the transmission belt 31.

  In this embodiment, the drive motor device 30 is configured independently of the multi-stage roots blower 3, but an integrated structure in which the drive motor device is directly connected can also be employed.

  As a result, the two three-lobe root rotors 15 and 15 are rotated at the same speed in opposite directions while maintaining a slight gap by the operation of the drive motor device 30, so that the air sucked from the silencer 22 is blown into the blower casing 4. The multi-stage Roots blower 3 is configured to be compressed in step S4 and discharged from the discharge port 6 to the discharge pipe 24.

  The discharge pipe 35 connected to the discharge pipe 24 is provided with an opening / closing valve 36 and a header 37. A large number of branch pipes 38 branched from the header 37 are connected to an on-off valve 39 and a check valve 40, respectively. An air diffuser unit 45 serving as an air diffuser is connected to the distal end portion 38 a forming the discharge port of the branch pipe 38 via a connection tube 42.

  As shown in FIG. 5, the cover-shaped holder 46 of the air diffuser unit 45 is fixed by welding its peripheral edge 46a so as to close a rectangular hole 71d opened at an appropriate location in the hull 71 from the inside. ing. And the after-mentioned diffuser tube main body 50 of the diffuser tube unit 45 is provided in the location retracted inward from the submerged surface 71c. Reference numeral 48 denotes a nozzle with a check valve attached so as to be kept airtight in a hole 46c formed in the side 46b of the holder 46.

  As shown in FIG. 6, the nozzle 48 with a check valve has a wall portion 49b formed at a substantially intermediate position in a cylindrical nozzle body 49 having a flange 49a at one end, and a valve provided at the center of the wall portion 49b. A valve chamber 51 is provided so as to communicate with the hole 50. Reference numeral 50 a denotes a valve seat formed in the valve hole 50. In the valve chamber 51, a rubber spherical valve 54 is movably inserted, and a stopper 52 is provided to prevent the spherical valve 54 from jumping out. A screw 49 c is formed on the outer periphery of the other end of the nozzle body 49. One end of the connection pipe 42 is inserted and fixed in the inlet hole 50 b communicating with the valve hole 50.

  The check valve 40 is provided, for example, to prevent the seawater or river water outside the ship from flowing back to the branch pipe side when the operation of the roots blower 3 is stopped. When the check valve-equipped nozzle 48 is used, the check valve 40 can be omitted because it has the same function as the check valve 40.

  Reference numeral 56 denotes a connecting member attached to one end of the diffuser tube body 55 having a predetermined length. The connecting member 56 is provided with a screw hole 57 for screwing into the screw 49 c of the nozzle 48 with check valve and a through hole 58 communicating with the screw hole 57. Reference numeral 60 denotes a stainless steel rod fixed to the central portion of the connecting member 56. On the other hand, a lid member 62 and a stainless-steel fixing piece 63 having a spring action are inserted into the tip of the rod 60 protruding from the diffuser tube main body 55, and the nut 64 is screwed to the rod 60 to attach the lid member 62. It is fixed.

  The diffuser tube body 55 is cylindrical and has a large number of small holes formed around it, or has a porous structure, and the material is preferably ceramic. The size of the diffuser tube main body 55 is an outer diameter of 50 to 100 mm and a length of 500 to 1000 mm. The amount of air discharged from one air diffuser is 200 to 500 liters per minute.

  The diffuser unit 45 uses one diffuser tube main body 55, but a diffuser tube unit 65 of the type using two diffuser tube main bodies 55 shown in FIG. 7 can also be adopted. Since the air diffuser unit 65 is configured in accordance with the air diffuser unit 45, the same reference numerals are used for the same components and the description is omitted.

  The nozzle 48 with a check valve is attached so that airtightness is maintained in a hole 46e formed in the top 46d of the holder 46. Reference numeral 66 denotes a T-shaped joint for connecting the nozzle 48 with a check valve and the two connecting members 56 by screwing a screw and a screw hole.

  As described above, the air sucked from the silencer 22 by the operation of the multi-stage roots blower 3 is supplied from the header 37 through the respective branch pipes 38 to the diffuser pipe unit 45, thereby generating a large amount of air generated from the diffuser pipe main body 55. A fine bubble generating device B in a hull according to the present invention that forms fine bubbles thickly on the submerged surface 71c of the hull 71 is configured.

  As shown in FIG. 8, according to the fine bubble generating device B in the hull according to the present invention, a large amount of fine bubbles k discharged from the diffuser tube main body 55 are formed thick on the submerged surface 71c of the hull 71, and the fine The frictional resistance of the hull is reduced by the bubbles k, and energy can be saved when the ship is in operation.

  In the above embodiment, the roots blower is described as the multi-stage roots blower 3. However, in consideration of pressure loss of the branch pipe 38 and the diffuser pipe unit 45, it is desirable to select and use one-stage or multi-stage roots blower. . Specifically, it is a standard to apply a one-stage blower when the draft is 0.5 to 3 m, a two-stage blower when the draft is 8 to 13 m, and a three-stage blower when the draft is 8 to 13 m. .

B: Microbubble generator 3 in a hull according to the present invention 3 ... multi-stage roots blower 4 ... blower casing 15 ... three leaf root rotor 35 ... discharge pipe 37 ... header 38 ... branch Tubes 45, 65 ... Diffuser units (diffuser tubes)
48 ... Nozzle with check valve 70 ... Ship 71 ... Hull 71c ... Submerged surface

Claims (3)

A device for generating fine bubbles in a hull that reduces the frictional resistance of the hull by discharging bubbles from a number of discharge ports arranged on the submerged surface of the hull to the submerged surface,
A single-stage or multi-stage roots blower in which a pair of three-leaf root rotors housed in a blower casing provided with a suction port and a discharge port are rotatably provided by a drive motor, and a discharge pipe connected to the discharge port side; A diffuser pipe connected to the tip of the discharge pipe forming the discharge port,
A large amount of fine bubbles are generated from the air diffuser by supplying the air sucked from the outside by the operation of the roots blower to the air diffuser, and the fine bubbles are formed thick on the submerged surface of the hull. A device for generating fine bubbles in a hull characterized by the above.   The apparatus for generating fine bubbles in a hull according to claim 1, wherein a header is provided in the discharge pipe, and a diffuser pipe is provided at a tip of a branch pipe connected to the header.   The fine bubble generating device for a hull according to claim 1 or 2, wherein a nozzle with a check valve is provided between a distal end portion of the discharge pipe or the branch pipe and the diffuser pipe.

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