Fine Bubble Generator And Water Treatment Device

Abstract

In a fine bubble generator having a structure in which a columnar portion protrudes from an orifice of a tubular member, the presence of the columnar portion inhibits a flow of a fluid, so that a flow rate of the fluid that generates fine bubbles is limited. In addition, foreign matter may be sandwiched between the columnar portions. It takes time and effort to manufacture the columnar portions. Furthermore, when the columnar portion is supported in a cantilever state, it is difficult to ensure mechanical rigidity and also to ensure durability.

A fine bubble generator includes: an inlet portion that gradually reduces in diameter from an inlet of a tubular body; an orifice continuous to the inlet portion; and an enlarged-diameter portion continuous to the orifice, and the inlet portion, the orifice and the enlarged-diameter portion are sequentially formed. A boundary between the orifice and the enlarged-diameter portion is a radially elevation surface, and a diameter of the enlarged-diameter portion is 3 to 10 times a diameter of the orifice. A concave portion is preferably formed in an outlet peripheral wall.

Claims

1-6. (canceled)

7. A fine bubble generator comprising: an inlet portion that gradually reduces in diameter from an inlet of a tubular body; an orifice continuous to the inlet portion; and an enlarged-diameter portion continuous to the orifice, the inlet portion, the orifice and the enlarged-diameter portion being sequentially formed, wherein an outlet peripheral wall of the orifice is a radial elevation surface, and the enlarged-diameter portion is opened only at an outlet on an extension of a center line of the orifice, wherein a concave portion is formed in the outlet peripheral wall.

8. The fine bubble generator according to claim 7, wherein a second concave portion or convex portion continuous or intermittent in a circumferential direction is formed in an inner peripheral surface of the enlarged-diameter portion.

9. The fine bubble generator according to claim 7, wherein the outlet peripheral wall is formed in a direction perpendicular (±20 degrees) to an axis of the orifice

10-16. (canceled)

17. The fine bubble generator according to claim 7, wherein the concave portion is evenly distributed in a circumferential direction and a radial direction about a center of the orifice in the outlet peripheral wall of the orifice.

18. The fine bubble generator according to claim 7, wherein a diameter of the enlarged-diameter portion is 3 to 10 times a diameter of the orifice.

19. A water treatment device comprising: the fine bubble generator according to claim 7; and a water supply unit that supplies water to the fine bubble generator.

20. The water treatment device according to claim 19, further comprising a fine bubble remover that removes the fine bubbles generated by the fine bubble generator.

21. A water treatment method comprising steps of: preparing the fine bubble generator according to claim 7; and supplying water to the inlet portion.

22. The water treatment method according to claim 21, wherein fine bubbles contained in water discharged from an outlet side of the orifice are removed.

23. A method for manufacturing fine bubble water, comprising steps of: preparing water; and treating the water with the fine bubble generator according to claim 7.

24. A method for manufacturing water, comprising steps of: preparing the fine bubble water manufactured according to claim 23; and removing some or all of fine bubbles from the fine bubble water.

25-26. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0065] FIG. 1 is a cross-sectional view of a fine bubble generator according to an embodiment of the present invention.

[0066] FIG. 2 is a front view of the fine bubble generator as viewed from an outlet side.

[0067] FIG. 3 is a chart illustrating measurement results of the generator of FIG. 1.

[0068] FIG. 4 illustrates simulation results of the generator.

[0069] FIG. 5 is a cross-sectional view of a fine bubble generator according to another embodiment.

[0070] FIG. 6 is a chart illustrating measurement results of the generator of FIG. 5.

[0071] FIG. 7 is a cross-sectional view of a fine bubble generator according to another embodiment.

[0072] FIG. 8 is a chart illustrating measurement results of the generator of FIG. 7.

[0073] FIG. 9 is a cross-sectional view of a fine bubble generator according to another embodiment.

[0074] FIG. 10 is a chart illustrating measurement results of the generator of FIG. 9.

[0075] FIG. 11 is a chart summarizing the results of FIGS. 3, 6, 8, and 10 on the same scale.

DESCRIPTION OF EMBODIMENT

[0076] FIG. 1 is a cross-sectional view illustrating a structure of a fine bubble generator 1 according to an embodiment of the present invention.

[0077] The fine bubble generator (hereinafter, sometimes simply referred to as a “generator”) 1 includes an inlet portion 10, an orifice 15, an enlarged-diameter portion 20, and concave portions 40 in a tubular casing 3.

[0078] The tubular housing 3 is composed of three pieces 4, 5 and 6, and a fitting hole 7 is formed in one end side (right side in the figure) of the first piece. This fitting hole 7 has a flat bottom surface (peripheral wall 8 of an opening of the orifice 15). The second and third pieces 5 and 6 penetrate into the fitting hole 7 without a gap.

[0079] At the other end (left side in the figure) of the first piece 4, the inlet portion 10 is conically formed and connected to the orifice 15. The orifice 15 is a through hole having the same radius and opens in the fitting hole 7. The orifice 15 and the inlet portion 10 align their center lines with a center line of the first piece 4.

[0080] In the first piece 4, the first concave portions 40 are formed in a bottom surface of the fitting hole 7, that is, in the peripheral wall 8 of the outlet of the orifice 15.

[0081] As illustrated in FIG. 2, the first concave portions 40 radially open at intervals of 90 degrees in the circumferential direction about a center of the orifice 15 in the peripheral wall 8.

[0082] In this example, the openings of the concave portions 40 each have a rectangular shape (oval coin shape) with rounded corners. The opening is formed in parallel with the orifice 15 while maintaining the shape of the opening.

[0083] The second piece 5 is a disk-shaped member fitted into the fitting hole 7, and a first enlarged-diameter portion 21 continuous to the orifice 15 is formed. A diameter of the first enlarged-diameter portion 21 is sequentially enlarged after passing through a central portion of the second piece 5 to form a second concave portion 23.

[0084] In this example, the second concave portion 23 is continuously formed in the circumferential direction of the inner peripheral surface of the second piece 5, but may be intermittent.

[0085] The disk-shaped third piece 6 is fitted into the fitting hole 7 so as to overlap the second piece 5. A second enlarged-diameter portion 25 is formed on the third piece 6, and is combined with the first enlarged-diameter portion 21 of the second piece 5 to constitute the enlarged-diameter portion 20 as the fine bubble generator 1.

[0086] In this example, the first enlarged-diameter portion 21 and the second enlarged-diameter portion 25 have the same diameter, but the diameter of the second enlarged-diameter portion 25 may be larger than that of the first enlarged-diameter portion 21.

[0087] All of the three pieces 4, 5, and 6 constituting the tubular casing 3 can be formed of synthetic resin. Of course, it can also be formed of metal or ceramics.

[0088] In the above description, all the first concave portions 40 are exposed to the first enlarged-diameter portion 21.

[0089] The first concave portions 40 may be radially expanded in the peripheral wall 8 such that, when the second piece 5 is fitted, they are partially covered with the second piece 5.

[0090] The first concave portions 40 are preferably formed radially about the center of the outlet of the orifice 15, and the formation directions are not limited to the four directions illustrated in FIG. 2. The first concave portions 40 can be arbitrarily formed in a range of, for example, 3 to 12 directions. It is preferable that each of the first concave portions 40 is evenly distributed in the circumferential direction and the radial direction when viewed from the center of the outlet of the orifice 15.

[0091] As a fine bubble generator of the example, a fine bubble generator having the following specification was prepared. The tubular casing 3 is made of ABS resin.

[0092] Tubular casing 3: diameter of 12.0 mm and length of 10 mm

[0093] Opening diameter of inlet portion: 8.0 mm

[0094] Opening angle of inclined surface of inlet portion: 90 degrees

[0095] Diameter of orifice 15: 0.9 mm

[0096] Length of orifice 15: 1.0 mm

[0097] Vertical width of first concave portion 40: 0.7 mm

[0098] Width of first concave portion 40: 0.4 mm

[0099] Depth of first concave portion 40: 0.5 mm

[0100] Distance between orifice 15 and first concave portion 40: 0.1 mm

[0101] Diameters of enlarged-diameter portions 21 and 25: 0.3 mm

[0102] Inclination angle of second concave portion 23: 90 degrees

[0103] Width of second concave portion 23: 0.75 mm

[0104] Fitting hole 7: diameter of 10 mm and depth of 4.0 mm

[0105] Thicknesses of second and third pieces: 2.0 mm

[0106] Tap water was introduced into the inlet side of the fine bubble generator 1 configured as described above at a pressure of 2.0 MPs, water discharged from the enlarged-diameter portion 20 side was collected, and the particle size distribution of fine bubbles contained therein was measured using SALD-7500H manufactured by Shimadzu Corporation.

[0107] The results are illustrated in FIG. 3.

[0108] The average particle size is 93 nm, and the number of nano-order fine bubbles per ml is more than 370 million. There were few micro-order fine bubbles.

[0109] A simulation of water stream in this example is illustrated in FIG. 4. In FIG. 4, the flow rate is indicated by color tones of an arrow. The lighter the color of the arrow, the faster the flow rate.

[0110] The pressure in the enlarged-diameter portion was 31.7 kPa, whereas the pressure in the first concave portion was 2.1 kPa and the pressure in the second concave portion was 2.9 kPa.

[0111] Next, the same test was performed on a sample (see FIG. 5) in which the second concave portion was omitted in the specification of FIG. 1.

[0112] The results are illustrated in FIG. 6.

[0113] The average particle size was 109 nm, and the number of nano-order fine bubbles per ml was about 130 million.

[0114] Next, the same test was performed on a sample in which the first concave portion was omitted in the specification of FIG. 5 (see FIG. 7).

[0115] The results are illustrated in FIG. 8.

[0116] The average particle size was 136 nm, and the number of nano-order fine bubbles per ml was about 77 million.

[0117] Next, the same test was performed on a sample in which the second concave portion was omitted in the specification of FIG. 7 (see FIG. 9).

[0118] The results are illustrated in FIG. 10.

[0119] The average particle size was 158 nm, and the number of nano-order fine bubbles per ml was about 48 million.

[0120] From the above results, many nano-order fine bubbles were generated even in a case where the first concave portion or the second concave portion was omitted.

[0121] FIG. 11 summarizes the results of FIGS. 3, 6, 8, and 10 on the same scale.

[0122] From the results of FIG. 11, it can be seen that providing the first concave portion and the second concave portion further reduces the particle size of the fine bubbles generated. It can be seen that the first concave portion and the second concave portion coexist, so that the particle size of the fine bubbles generated is remarkably reduced, and as a result, the number of fine bubbles generated is remarkably increased.

[0123] From the above, the present inventor has obtained the following finding.

[0124] A fine bubble generator including: an inlet portion that gradually reduces in diameter from an inlet of a tubular body; an orifice continuous to the inlet portion; and an enlarged-diameter portion continuous to the orifice,

[0125] the inlet portion, the orifice and the enlarged-diameter portion being sequentially formed, wherein

[0126] a boundary between the orifice and the enlarged-diameter portion is a radial elevation surface,

[0127] a diameter of the enlarged-diameter portion is 3 to 10 times a diameter of the orifice, and

[0128] the enlarged-diameter portion is released only at an outlet thereof.

[0129] In the above description, the boundary between the orifice and the enlarged-diameter portion corresponds to the outlet peripheral wall of the orifice. The outlet peripheral wall is preferably in a direction perpendicular to the axis of the orifice, but may have an inclination of ±20 degrees or ±10 degrees from the perpendicular. Here, the enlarged-diameter portion side is defined as “+” and the inlet portion side is defined as “−” about the outlet of the orifice.

[0130] When the inclination of the outlet peripheral wall exceeds +20 degrees, the bubbles formed due to the cavity effect are insufficiently stirred and mixed. On the other hand, when the inclination of the outlet peripheral wall exceeds −20 degrees, the water stream discharged from the orifice is drawn toward the inclined outlet peripheral wall side, so that a sufficient flow rate cannot be secured, and thus the pressure reduction becomes insufficient.

[0131] When the diameter of the enlarged-diameter portion is less than three times the diameter of the orifice, the pressure reduction becomes insufficient. On the other hand, when the diameter of the enlarged-diameter portion exceeds 10 times the diameter of the orifice, the water stream discharged from the outlet of the orifice is excessively dispersed to inhibit the water stream. Therefore, a sufficient flow rate cannot be secured, and the pressure reduction becomes insufficient.

[0132] The enlarged-diameter portion preferably has a uniform inner diameter as illustrated in the drawings, but may have an inverted funnel shape within the above range.

[0133] The enlarged-diameter portion is released only at its outlet. In other words, no air or other gas is injected from the outside into the peripheral wall of the enlarged-diameter portion. When the enlarged-diameter portion communicates with an external environment other than the outlet thereof, the reduced pressure environment in the enlarged-diameter portion may be disturbed, which is not preferable.

[0134] The second concave portion is formed at a position where the water stream discharged from the outlet of the orifice can be efficiently stirred. The second concave portion can be arbitrarily designed according to the flow rate, the diameter ratio between the orifice and the enlarged-diameter portion, the shape of the enlarged-diameter portion, and the like. According to the present inventors' study, it is preferable that the diameter of the second concave portion should be formed in a range of 0.5 to 1.5 times the diameter of the enlarged-diameter portion from the outlet of the orifice toward the downstream side in the axial direction of the orifice.

[0135] Hereinafter, the following matters will be disclosed.

[0136] (1)

[0137] A fine bubble generator including: an inlet portion that gradually reduces in diameter from an inlet of a tubular body; an orifice continuous to the inlet portion; and an enlarged-diameter portion continuous to the orifice,

[0138] the inlet portion, the orifice and the enlarged-diameter portion being sequentially formed, wherein

[0139] a radial elevation surface as a boundary between the orifice and the enlarged-diameter portion is formed with a first concave portion evenly distributed in a circumferential direction and a radial direction about a center of the orifice, and

[0140] an inner peripheral surface of the enlarged-diameter portion is formed with a second concave portion or a convex portion continuous or intermittent in the circumferential direction.

[0141] (2)

[0142] A water treatment device including:

[0143] a water stream compression unit having a peripheral wall which uniformly compresses a water stream; and

[0144] a water stream release unit formed downstream of the water stream compression unit and having a larger diameter than that of the water stream compression unit, wherein

[0145] a first concave portion recessed in a direction opposite to the water stream is formed in the water stream release unit, and

[0146] a pressure in the first concave portion is smaller than a pressure of the water stream released from the water stream compression unit to the water stream release unit.

[0147] (3)

[0148] The water treatment device according to (2), in which the pressure in the first concave portion is 1/10 to 1/100 of the pressure at a center of the water stream release unit.

[0149] (4)

[0150] The water treatment device according to (2), in which a second concave portion is formed in a circumferential direction on an inner peripheral surface of the water stream release unit, and a pressure in the second concave portion is larger than the pressure in the first concave portion and smaller than a pressure at the center of the water stream release unit.

[0151] (5)

[0152] The water treatment device according to (2), in which a concave portion continuous or intermittent in the circumferential direction or a convex portion continuous or intermittent in the circumferential direction is formed in the inner peripheral surface of the water stream release unit, and stirs the water stream released from the water stream compression unit.

[0153] (6)

[0154] The water treatment device according to any one of claims (2) to (5), further including a device that removes fine bubbles from the water stream released from the water stream release unit.

[0155] The present invention is not limited to the description of the embodiments of the invention. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive them without departing from the recitation of the claims.

DESCRIPTION OF REFERENCE NUMERALS

[0156] 1, 101, 201, 301 Fine bubble generator [0157] 8 Peripheral wall of outlet of orifice [0158] 10 Inlet portion [0159] 15 Orifice [0160] 20 Enlarged-diameter portion [0161] 23 Second concave portion [0162] 40 First concave portion