JPH10235174A - Pressurization type gas-mixing method and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a gas dissolving speed and to transfer treated water to a next treatment process while continuously mixing gas with treated water. SOLUTION: Treated water is charged in a vessel 1 into which compressed air is introduced under pressure while centrifugal force is generated by rotating a rotary plate 4 to be allowed to continuously flow down toward the lower part of the vessel 1 while a water film is formed to the entire periphery of the inner wall of the vessel 1 to be brought into contact with compressed air. Air bubble-containing treated water stored in the lower part of the vessel can be transferred to a next treatment process continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized gas mixing method used in a pressurized flotation method and the like, and an apparatus used for the method.

[0002]

2. Description of the Related Art One example of a method for separating an aqueous suspension is bubble flotation. In this method, air is dissolved in water under pressure and then released, and fine bubbles are precipitated at the interface of the suspended particles by depressurization of the water, or particles are attached to the precipitated bubbles, and the suspended particles are removed. It floats and separates.

A conventional apparatus used in this method includes a pressurized tank for storing a processing solution, a ventilating device for ventilating compressed air to the pressurized tank, and a pressure-adjusting valve or the like adjacent to the pressurized tank. And a pressurized flotation device comprising a flotation tank. In addition, there are a decompression tank for performing decompression treatment of one tank from atmospheric pressure, and a vacuum flotation device that uses a flotation tank for suspended particles.

In the pressurized flotation apparatus, the gas is dissolved in the processing liquid by forcibly ventilating the processing liquid in the pressurized tank while stirring the processing liquid. By sending the processing liquid to the flotation tank while reducing the pressure, the dissolved gas becomes bubbles in the flotation tank, and the object to be processed is floated on the surface of the processing liquid, and the suspended matter is scraped and collected. I try to separate the minutes.

In the vacuum flotation apparatus, a certain amount of the processing liquid supplied into the tank is subjected to a reduced pressure treatment to dissolve dissolved gas as bubbles, and is provided in the tank in advance. The suspended matter is scraped and collected by the suspended matter scraping means in the same manner as in the flotation tank.

[0006]

However, for example, in any of the above-mentioned apparatuses, the tank is once closed after being filled with treated water, and the tank is ventilated in this closed state until the gas becomes saturated. Dissolution work is performed, and then the pressure reducing valve is opened, processing such as transfer of the treated water to the flotation tank is performed, and then the suspended matter is collected. However, the processing capacity is limited and the processing capacity is limited. In order to increase the processing capacity, the entire apparatus must be enlarged.

[0007] Further, even if such a large size,
Since the pressured air contacts only the interface and the water surface when ventilating the treated water, the contact area is small, the air mixing efficiency is small, and it takes time to dissolve the gas. The removal amount of the suspension per unit time was small.

The present invention has been made to solve the above problems, and an object of the present invention is to improve the rate of dissolving gas and to remove suspended solids while continuously mixing gas with treated water. It is an object of the present invention to provide a pressurized gas mixing method that can be transferred to the next processing step for reducing the pressure. Another object of the present invention is to provide a pressurized mixing device having a small and simple structure for achieving the above method.

[0009]

In order to achieve the above object, a method of the present invention is to provide a method in which treated water is supplied while generating centrifugal force into a vessel into which pressurized air is press-fitted. A pressurized gas mixing method is characterized by continuously flowing down toward the lower side of the vessel while forming a water film w all around, and contacting and mixing with the pressurized air. Therefore, in this method, the entire surface of the vessel becomes the contact area between the water film of the treated water and the pressurized air on the inner peripheral surface of the vessel, and can be brought into contact for a period of time while flowing down. In comparison, the contact area is significantly increased, and the gas dissolution rate can be increased. Furthermore,
When treated water is blown from the center of the vessel to the inner wall at the time of introduction of the treated water, the surface of the water droplet flying in the pressurized air until the treated water reaches the inner wall of the vessel becomes a contact area. The dissolution rate can be increased.

In this pressurized gas mixing method, the pressure-treated water collected in the lower part of the vessel is subjected to a pressure-reducing treatment to precipitate fine bubbles, and the pressure-treated water is subjected to the next treatment step for floating separation of suspended particles. A transfer step can be performed. Therefore, in this method, the treated water flowing down to the lower part of the vessel contains sufficient gas, and the treated water whose gas dissolution rate has been increased is continuously stored,
This can be sequentially transferred from the bottom of the vessel to the next processing step in which the suspended particles are floated and separated, thereby enabling continuous processing.

[0011] Further, for the above-mentioned object, the apparatus of the present invention comprises:
A closed vessel type vessel with a temporary storage tank provided at the lower part and a pressurized air inlet at an appropriate position on the upper part, and a rotatable bearing inside the upper center position of the vessel and numerous openings formed around it A bottomed container-shaped rotating plate, a drive motor connected to the rotating plate, and a treated water inlet opening toward the inside of the rotating plate near the upper center position of the vessel. This is achieved by a pressurized gas mixing device. With such a configuration of the pressurized gas mixing device, the treated water charged into the vessel is caused to generate a centrifugal force by the rotation of the rotating plate, is blown to the inner wall of the vessel, and flows down the inner wall. The air pressurized during such a flight and down flow dissolves sufficiently and evenly quickly in the treated water.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Figure 1,
Reference numeral 2 denotes a pressurized gas mixing device to which the method of the present invention is applied. The mixing device includes a cylindrical closed vessel-shaped vessel 1 integrally formed with a funnel-shaped reduced diameter portion 1a at a lower portion, and a temporary storage tank 2 provided at the bottom of the vessel 1.

At an appropriate position above the vessel 1, a pressurized air inlet 3 is opened, and a rotary plate 4 is rotatably supported in the center, and the rotary plate 4 is located at the center of the top of the vessel 1. Is connected to an output shaft 5a of a rotation driving motor 5 disposed at a position indicated by the arrow, and the driving motor 5 rotates at a high speed. The rotating plate 4 has a bottomed container shape, and has a number of holes 4a formed around the rotating plate 4 for flowing inside and outside thereof. Further, a treated water inlet 6 is formed in the vicinity of the upper center position of the vessel 1 toward the inner peripheral side of the rotary plate 4, and the treated water in a suspended state sent through the pressurizing pump 8 is introduced into the inlet. The processing water is once supplied into the rotating plate 4 through the motor 6, and the centrifugal force generated by the rotation of the rotating plate 4 driven by the motor 5 generates a vortex in the treated water, and blows the surrounding water through the hole 4a as indicated by an arrow.

The vertical dimension L of the straight body portion of the vessel 1 is set to 1/2 to 5/2 of the vessel diameter D, and the diameter of the rotating plate 4 is set to 1/3 to 2/3 of the vessel diameter D. It is desirable to set the number of rotations at the outermost peripheral speed of about 5 to 40 m / sec.

As described above, the treated water introduced into the vessel 1 is immediately splashed by the rotary plate 4 from the vicinity of the center of the vessel 1 toward the inner wall in the form of water droplets, and the treated water is deposited on the inner peripheral wall of the vessel. Flies in the pressurized air before the air reaches the air, and is mixed with the air. Further, on the inner peripheral wall surface of the vessel 1, it flows down by spontaneous fall while adhering and rotating as a thin water film W having a thickness of 0.5 to 5 mm on the entire surface thereof, and simultaneously blows through the inlet 3 while flowing down. The air comes into contact with the pressurized air to be mixed into the thin film W of the treated water. Due to the large contact area, it dissolves according to the amount of pressurized air while contacting air enough to flow down, so that the air mixing ratio is shorter than the conventional pressurized tank type. Can be higher.

The treated water mixed with air is stored in a temporary storage tank 2 below the collected water while gathering in the reduced diameter portion 1a. Further, the treated water passes through the temporary storage tank 2 and is floated or separated. Separation process 7 which is a vacuum flotation tank
(Water / suspension separation means). This separation step 7
In this case, the generation of air bubbles due to the reduced pressure is promoted, the suspended matter is caused to float by the adhesion of the suspended matter and the air bubbles, and the solid matter is separated by collecting the floated suspended matter as scum.

The above-described transfer operation can be performed automatically and continuously by the air pressure in the vessel 1, and the control for the transfer is only to monitor the water level in the vessel 1 within a certain range. In addition, the control operation can be performed easily as compared with the related art, and the response to the load fluctuation can be smoothly performed. In the above-described embodiment, the centrifugal force is generated in the treated water introduced into the vessel 1 by rotating the rotating plate 4 at a high speed. However, the centrifugal force is generated by rotating the vessel 1 itself. Can also.

[0018]

Embodiment: Internal volume 35 l, dimensions L / diameter D = 5 of straight body
/ 3, using a vessel with a processing flow rate of 2.5 l / min per minute, continuously mixing gas into the processing water supplied into the vessel at a pressure of 300 KPa in the vessel and a peripheral speed of the rotary plate of 7.5 m / sec. to perform, as a result of the continuous measurements of the air solubility in the outlet side, on average O ₂ conversion was about 20%.

[0019]

As described in detail above, the pressurized gas mixing method and apparatus according to the present invention have the following effects. Since it comes into contact with pressurized air in the state of water droplets / water films, the contact area is large and the contact time is long, so that the gas dissolution rate can be improved. Further, the amount of pressurized air can be reduced as compared with the related art. In the state of flowing down to the lower side of the vessel, sufficient air is dissolved in the treated water, and this can be continuously transferred to the next process as it is, so that continuous processing is possible, processing capacity is improved, and load fluctuation Correspondence becomes smooth. The device can be reduced in size and simplified.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a pressurized gas mixing apparatus to which the method of the present invention is applied.

FIG. 2 is a sectional view taken along line AA of FIG.

[Description of Signs] 1 Vessel 2 Temporary storage tank 3 Pressurized air inlet 4 Rotating plate 4a Hole (opening) 5 Drive motor 6 Treated water inlet 7 Separation process

Claims (4)

[Claims] 1. A process water is injected into a vessel into which pressurized air is injected while generating a centrifugal force, so that a water film is continuously formed on the entire inner wall of the vessel toward the lower side of the vessel. Flow down and contact with the pressurized air.
A pressurized gas mixing method characterized by mixing. 2. The pressurized process according to claim 1, wherein the pressurized process water is transferred to a next process step of removing suspended particles by depressurizing the pressurized process water collected at a lower portion of the vessel. Gas mixing method. 3. A closed vessel type vessel having a temporary storage tank provided at a lower portion and a pressurized air introduction port provided at an appropriate position at an upper portion, a rotatable bearing inside an upper central position of the vessel, and a plurality of vessels arranged around the vessel. A bottomed container-shaped rotating plate having an opening formed therein, a drive motor connected to the rotating plate, and a treated water inlet opening toward the inside of the rotating plate near an upper center position of the vessel. And a pressurized gas mixing device. 4. A water / suspension separating means for transferring the pressurized treated water collected at a lower portion of the vessel, performing a treatment under atmospheric pressure or reduced pressure, and separating a floating suspended matter. The pressurized gas mixing device according to claim 3, wherein: