JPH0258972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gas-liquid contact device, and more particularly to a gas-liquid contact device having a porous rotating drum, which improves the degree of dispersion of air bubbles.

[Prior Art] A gas-liquid device in which a porous drum is provided in a tank body so as to be submerged in water, and gas is supplied under pressure into the drum and the drum is rotated to eject air bubbles into the liquid from the circumferential surface of the drum. Contact devices are known (for example, Japanese Patent Publications No. 52-21991 and No. 52-22953).

Such a gas-liquid contact system using a porous cylindrical drum includes a vertical type in which the drum is installed so that its axial direction is substantially vertical, and a horizontal type in which the drum is installed horizontally. The former vertical type (for example, the above-mentioned Japanese Patent Publication No. 52-21991) has a simpler drum pivot mechanism than the latter horizontal type.
It has the feature of being particularly suitable for small size and small capacity specifications.

[Problems to be Solved by the Invention] However, in the conventional vertical rotating drum type gas-liquid contact device, since the drum is cylindrical as shown in FIG. The ejected air bubbles tend to gather in a portion close to the drum side circumferential surface and rise upward. Therefore, it is difficult for the bubbles to be dispersed throughout the entire area inside the tank body, and the bubbles tend to meet and coalesce to become coarse, resulting in low gas-liquid contact efficiency.

[Means for Solving the Problems] The present invention is a gas-liquid contact device equipped with a vertical rotating drum, in which the drum has a shape that expands in diameter downward.

Note that the gas supply pipe is inserted into the drum, for example, from the center of the bottom of the drum.

[Function] In the gas-liquid contact device of the present invention, the gas supplied into the drum from the gas supply pipe is sequentially ejected from the openings provided on the circumferential surface of the drum. On this occasion,
The drum is being rotated, and the gas ejected from the openings is subjected to shearing action, etc., and becomes minute bubbles.

According to the present invention, since the drum has a shape whose diameter increases downward, (a) the openings are distributed horizontally.

(b) At the bottom of the drum, the circumferential speed increases and the rotational speed of the liquid also increases. This increases the centrifugal force of the liquid and disperses the bubbles further away from the drum.

(c) Therefore, coalescence of bubbles is prevented.

(d) The residence time of air bubbles in the liquid becomes longer.

Due to these effects, fine air bubbles become widely dispersed and the gas-liquid contact efficiency is increased.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a front cross-sectional view showing the configuration of a gas-liquid contact device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of essential parts thereof.

Reference numeral 10 is a tank body, and a motor 16 is fixed to a pedestal 14 provided via a support 12. The motor 16 is installed so that its rotating shaft 16a is vertically oriented, and a truncated conical rotating drum 18 is attached to a nut 20 at the lower end of the rotating shaft 16a.
It is attached by. The drum 18 has a lid and a bottom, and its axis of rotation is in the vertical direction.

This drum 18 has a large number of openings 2 on its side circumferential surface.
2 is opened, and a gas jet nozzle 24 is provided protruding from the outer peripheral side of this opening 22. In this embodiment, the openings 22 are arranged in a grid pattern.

A base plate 26 is fixed to the bottom surface of the tank body 10, and a gas supply pipe 28 is raised from this base plate 26. This gas supply pipe 28 penetrates the bottom plate 18a of the drum 18 and reaches near the top inside the drum 18. Note that within the drum 18, the gas supply pipe 28 has a truncated conical shape. Further, the drum bottom plate 18a is provided with an opening through which the gas supply pipe 28 is inserted, and a sliding member 30 is provided at the edge of this opening to prevent the lower end of the drum 18 from rotating. It has come to form the backbone of the

In the device of this embodiment, the truncated conical partition wall 32 having a smaller diameter than the drum 18 is connected to the canopy section 18 of the drum 18.
It is installed vertically from b. This partition wall 32 is smaller in height than the drum 18, and a communication portion 34 is formed between the lower end of the partition wall 32 and the drum bottom plate 18a. Additionally, a passing pressure loss is applied to the gas flow rising between the partition wall 32 and the inner circumferential surface of the drum 18, so that the gas maintains an extremely small pressure (static pressure) upward. Apertures 36 for this purpose are provided in multiple stages. Note that the lower part of the gas supply pipe 28 is T-shaped, and a flexible tube 38 is connected thereto.

In the gas-liquid contact device having such a configuration, gas is supplied into the rotating drum 18 through the flexible tube 38 and the gas supply pipe 28, and the motor 1
6 is rotated, the gas flows around the communication part 34 at the lower end of the partition wall 32 and between the partition wall 32 and the drum 18.
The liquid rises between the inner circumference and is sequentially ejected from the nozzle 24. Then, due to the shearing action caused by the rotation of the drum 18, it is finely divided into fine bubbles.

According to the present invention, since the diameter of the drum 18 increases toward the bottom, the openings 22 (nozzles 24) are distributed in the horizontal direction, and the air bubbles are dispersed over a wider range in the horizontal direction inside the tank. I come to do it.

Also, when the drum 18 is rotated, the drum 18
The liquid in contact with the outer periphery also obtains the required rotational force in the circumferential direction and circulates in a spiral shape, but in the present invention, since the diameter of the drum is larger toward the bottom, the circumferential speed becomes higher toward the bottom of the drum.

As a result, the liquid in the tank rotates at a higher speed toward the bottom of the drum, and the speed in the direction away from the drum axis also becomes faster toward the bottom of the drum.
Therefore, the air bubbles ejected into the liquid stream also move away from the drum axis at a higher speed toward the lower part of the drum.

In this manner, according to the present invention, as shown in FIG. 3, the bubbles can reach locations far from the drum axis, resulting in extremely high bubble dispersion. Note that FIG. 4 is shown as a comparative example, and schematically shows the state of bubble dispersion in a cylindrical drum type gas-liquid contact device. As shown in Figure 4,
In the cylindrical drum 38A, air bubbles spread only to a portion close to the drum axis, and there are almost no air bubbles near the wall surface of the tank body 10.

In particular, in this embodiment, the throttles 36 are provided in multiple stages, and due to the pressure loss when passing through the throttles 36, the gas rising between the partition wall 32 and the inner circumferential surface of the drum 18 is reduced as it flows upward. Retention pressure decreases. Therefore, by adjusting the opening degree of the throttle 36 as appropriate, it is possible to eject gas at a higher pressure from the nozzles located lower on the drum. If you do this,
The bubbles ejected from below the drum move away from the drum more quickly, and the degree of dispersion of the bubbles becomes even higher.

Note that the opening degree of the throttle 36 can also be adjusted so that the difference between the water pressure and the gas pressure inside and outside the drum 18 in each nozzle 24 becomes approximately equal. In this case, it becomes possible to eject an equal amount of gas per unit time from each nozzle 24, and the diameters of bubbles generated from each nozzle 24 are made equal.

Note that before the apparatus of this embodiment starts operating, the drum 18 contains liquid. This liquid is pushed by the gas supplied from the gas supply pipe when the apparatus starts operating, and is also discharged out of the drum 18 by the rotational centrifugal force of the drum 18.

In the embodiment described above, since the nozzle 24 is provided in a protruding manner, the gas is ejected at the cylinder where the speed of the liquid rotating together with the drum 18 is reduced, and the shearing effect of the ejected gas is correspondingly high, and the air bubbles are finely formed. It has the effect of becoming. That is, when the drum 18 is rotated, the liquid in contact with the side circumference of the drum 18 also rotates with the drum 18, but the speed of the liquid decreases as it moves away from the surface of the drum 18.

Therefore, the relative velocity difference between the tip of the nozzle 24 and the liquid is larger than that at the surface of the drum 18.
This makes it possible to apply a large shearing force to the ejected gas.

Further, in the above embodiment, the drum bottom plate 18a is configured to be pivotally supported by the gas supply pipe 28 via the sliding member 30, and the drum 18 is supported in two places, upper and lower, and stable rotation can be performed. effective.

In the above embodiment, the drum 18 has a truncated conical shape, but the present invention is not necessarily limited to this. For example, a conical shape or one whose diameter expands in a stepwise manner can also be adopted. Moreover, it does not have to be cylindrical, and may be polygonal. Further, in the present invention, the drum bottom plate is not essential, and may be provided with a lid and without a bottom. In this case, a spoke is installed at the lower end of the drum to extend in the radial direction, and a gas supply pipe 2 is attached to the tip of the spoke.
A boss member that loosely fits into 8 may be fixedly provided.

[Effect] As described above, according to the present invention, it is possible to increase the degree of dispersion of bubbles and to make the bubbles finer.
Provided is a gas-liquid contact device with a long bubble residence time and high gas-liquid contact efficiency. The gas-liquid contact device of the present invention includes:
It can be very suitably applied to various water treatment devices, devices for supplying air and oxygen to aquaculture fish tanks, gas-liquid contact reaction devices, gas absorption devices, wet dust collectors, gas desulfurization devices, and other devices.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of the device of the present invention, and FIG.
The figure is an enlarged view of the same main part, and FIGS. 3 and 4 are schematic diagrams showing the state of dispersion of bubbles. 10... Tank body, 18... Rotating drum, 22...
Opening, 24... Nozzle, 28... Gas supply pipe, 3
2... Partition wall.

Claims (1)

[Claims] 1. Comprising a tank body, a rotating drum installed in the tank body with the axial direction in a substantially vertical direction and having a large number of gas ejection ports on the side circumferential surface, and a gas supply pipe connected to the rotating drum. , and the rotating drum has a shape whose diameter increases downward.