JPH03238080A - Pressurized floating separating device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the convection phenomenon of water being treated in a floating tank and improve the treating performance outstandingly remarkably by supplying water to be treated flowing out from a mixing chamber to the liq. surface of a floating tank. CONSTITUTION:An untreated water and a pressurized water are supplied into a mixing a chamber 21 from its bottom part. A mixture of the untreated water and the pressurized water thus made up in the mixing chamber 21 and intended to be treated is supplied from the upper part of the mixing chamber 21 to the liq. surface of a floating tank 20 by a mixture supply means 40 with the floating matter adhered to the liq. mixture attached to the air bubbles. A liq. mixture collecting opening 56 is provided at the bottom part of the floating tank 20. A floating matter 50 separated on the liq. surface of the floating tank 20 is removed therefrom by a floating matter removal means consisting of a floating matter discharge pump 59, a skin rake 51 and a suction cup 52. The liq. surface of the floating tank 20 is retained at a predetermined height by a gage pipe 57. As a result, the occurrence of convection phenomenon of the water being treated in the floating tank is prevented and the treating performance is improved outstandingly remarkably.

Description

[Detailed description of the invention] (Field of industrial application) Uninvented, a pressurized flotation separation device that uses fine air bubbles to float and separate solid particles, which are suspended substances contained in water to be treated. It is related to.

(Prior technology) Pressure flotation is a process in which air is dissolved in the water by pressurizing the water that contains suspended solids in the form of particles, and the pressurized water is constantly heated. When the water is returned to pressure, the air that has been dissolved in the water to be treated becomes fine bubbles and is liberated, so this method separates solid and liquid by attaching these fine bubbles to the particles in the water and making them float. be.

Conventional pressurized flotation separation methods include a total pressurization method in which all of the water to be treated is pressurized, a partial pressurization method in which a part of the water to be treated is pressurized, and a part of the treated water that has undergone solid-liquid separation is pressurized. A method of pressurizing circulating water is known in which the water is pressurized and supplied to the water to be treated.

FIG. 5 shows a specific example of a conventional method for pressurizing circulating water, in which flotation separation is performed by supplying raw water to be treated into a liquid in a flotation tank and performing flotation separation within the liquid.

1 is a flotation tank, and 2 is a discharge pipe for water to be treated, which are installed in the flotation tank 1. Reference numeral 3 denotes a water collection pipe, which is installed near the bottom of the flotation tank I, and is for discharging treated water that has been separated into solid and liquid in the flotation tank I. 4 is a treated water tank which houses a water level pipe 5 connected to the water collecting pipe 3, and this water level pipe 5.
The height of the upper surface of or the water level of the flotation tank I is determined.

6 is a treated raw water tank; 7 is a pressure tank; 7 is a pressure tank; the treated raw water tank 6 and the mixer 7 are connected via a pump 9; and is connected to the mixer 7. Further, the mixer 7 is connected to the treated water discharge pipe 2. Note that 11 is an air intake port for introducing air into the pressurized tank 8.

Reference numeral 12 denotes a skim rake for scraping up floating objects accumulated on the liquid surface of the flotation tank 1, and is connected to a drive shaft of a motor 13 and is rotatably installed.

14 is a floating object discharge port provided at the upper part of the flotation tank 1; 15;
is a sediment rake for scraping up sediment that has settled in the flotation tank l.

In the separator constructed as described above, the treated water in the treated raw water tank 6 is supplied to the mixer 7 by the pump 9. Further, a part of the separated treated water is supplied to a pressurizing tank 8 by a pump 10, and in the pressurizing tank 8, it is pressurized together with air supplied from an air intake port 11 and supplied to a mixer 7. The treated raw water supplied to the mixer 7 is mixed with pressurized treated water and sent under pressure to the treated water discharge pipe 2.

The water to be treated is supplied under pressure from the water discharge pipe 2 into the flotation tank 1 and returns to normal pressure by being discharged into the liquid at normal pressure. The trapped air becomes fine bubbles, which are released and float to the surface along with the particles in the water to be treated.

The floating objects floating on the liquid surface of the flotation tank are collected by a skim rake 12 and taken out from a floating object discharge port 14. The solid-liquid separated treated water is sent to the treated water tank 4, part of it is discharged, and part of it is pressurized as described above and sent to the flotation tank 1.
is then fed again for separation processing.

In both the conventional technology shown in Fig. 5 and other conventional separation methods, the water to be treated and pressurized water are supplied into the liquid in the flotation tank for flotation separation. A convection phenomenon occurs within the tank, and as a result, the water to be treated that is supplied into the flotation tank is agitated by the convection phenomenon. As mentioned above, float separation separates solid and liquid by attaching particles to microbubbles and making them float. Therefore, when the water to be treated is agitated in the flotation tank, once the particles are removed from the flotation tank, Since the particles float after reaching near the bottom of the particle, it takes a long time for all the particles to finish floating. Therefore, the only way to increase the separation efficiency of the water to be treated is to increase the size of the flotation tank.

In the conventional technology, when the amount of water to be separated and treated increases, it is necessary to provide a large-scale flotation tank, which poses problems such as poor equipment investment efficiency.

(Problem to be solved by the invention) The present invention prevents the occurrence of convection due to the water to be treated in the flotation tank by supplying the water to be treated above the liquid surface of the flotation tank, thereby significantly improving treatment performance. It is an object of the present invention to provide a pressurized flotation separation device that allows

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a flotation tank, a mixing chamber in which treated raw water and pressurized water are supplied from the bottom, and a mixture of treated raw water and pressurized water in the mixing chamber. a water-to-be-treated supply means for supplying treated water from the top of the mixing chamber to the liquid surface of the flotation tank in a state in which suspended substances contained in the water to be treated are attached to air bubbles, and treated water provided at the bottom of the flotation tank; a water collection port, a floating object removing means for removing floating objects floated and separated on the liquid surface of the flotation tank, and a water surface height holding means for maintaining the water surface height of the flotation tank at a predetermined height. It is characterized by

(Function) The treated raw water and pressurized water supplied to the bottom of the mixing chamber are mixed in the mixing chamber, but since the mixing chamber is at atmospheric pressure, they gradually flow upward while precipitating air bubbles inside the mixing chamber. The precipitated air bubbles adhere to particles, which are suspended substances contained in the water to be treated, and are supplied from the upper part of the mixing chamber onto the liquid surface of the flotation tank.

Therefore, particles whose specific gravity has become smaller due to the adhesion of air bubbles float on the liquid surface of the flotation tank, and these floated and separated particles are scraped up to the suction cup by the skimmer and suctioned away by the removal pump.

Furthermore, since the water to be treated flowing out from the mixing chamber is supplied to the liquid surface of the flotation tank, no convection phenomenon occurs in the flotation tank due to the supplied water to be treated.

For this reason, the treatment residence time in the flotation tank is shortened, making it possible to significantly increase the throughput per unit volume of the flotation tank.

(Embodiment) FIGS. 1 and 2 show a first embodiment, in which FIG. 1 is a vertical sectional view of the entire assembled apparatus of the present invention, and FIG. 2 is a plan view thereof.

The first embodiment is a circulating water pressurization system. In these figures, the flotation tank 20 has a circular planar shape, and a cylindrical mixing chamber 21 is provided in the center of the tank.
A treated raw water supply port 22 and a pressurized water supply port 23 are provided at the bottom of the tank. The treated raw water supply port 22 is connected to the treated raw water tank 24
The pressurized water supply port 23 is connected to a pressurized tank 25.

The treated raw water tank 24 is equipped with a pump 26 and a flow rate adjustment valve 2.
7 and the flow meter 28 to the treated raw water supply port 22, the treated raw water stored in the treated raw water tank 24 and the pressurized water stored in the pressurized tank 25 are respectively supplied to the mixing chamber. It is designed to be supplied to the bottom of 21.

The pressurized tank 25 stores treated water taken out from a treated water tank 29 provided outside the flotation tank 20, which is pressurized together with air by a pressurized water pump 30. Further, a pressure reducing valve 31 is provided in the passage between the pressurized water supply port 23 and the pressurized tank 25. A flow meter 72 and a flow rate adjustment valve 33 are also provided. Furthermore, a chemical tank 34 storing a chemical such as a coagulant is connected between the pressure reducing valve 31 and the flow meter 32 via a chemical supply pump 35. 36 is a medicine stirring means for the medicine tank 34. 37 is the treated water tank 29 and the pressurized water pump 30
This is an air intake port installed between the plant and the plant, which allows the flow rate of treated water to be adjusted.

At the upper end of the mixing chamber 21, an arm-shaped rotary cylinder 38 with its bottom facing upward is rotatably provided. The rotating cylinder 38
An outlet 39 is formed in the outlet 39, and a horizontal distribution pipe 40 is fixed in communication with the outlet 39. Further, the distribution and dispersion pipe 40 has a dispersion port 41 that opens along the pipe, and the water to be treated (a mixture of treated raw water and treated water) that flows out (overflows) from the outflow port 39 is distributed. The liquid is sprayed and supplied to the liquid level in the flotation tank 20 from above through a dispersion pipe 40.

Further, a drive shaft 43 that projects vertically from a frame 42 that covers the upper surface of the flotation tank 20 and is rotatable is fixed to the rotary cylinder 38, and a drive shaft 43 that drives a rotary drive device 44 provided on the frame 41 is fixed to the rotary cylinder 38. A gear 45 and a driven gear 46 provided at the upper end of the drive shaft 43 are interlocked by a chain 47.

Note that 48 is a seal structure installed between the mixing chamber 21 and the rotating cylinder 38, and 49 is a bearing installed between the frame 42 and the drive shaft 43.

Furthermore, inside the flotation tank 20, there is a ski rake 51 for scraping up the floating objects 50 that have been floated and separated on the liquid surface of the flotation tank as the rotary cylinder 39 rotates, and the floating objects 50 that have been scraped up by the skim rake 51. A suction cup 52 is provided to suck the water.

This skim rake 51 is provided on a mounting rod 51a fixed to the rotary cylinder 38, and is tilted toward the suction cup 52 so that the floating objects 50 are gathered together.

In addition, a sediment rake 54 is provided to scrape sediment deposited at the bottom of the flotation tank 20 into the sediment removal port 53. The sediment rake 54 is provided in a radial direction around the mixing chamber 21, is connected to the rotary cylinder 39, and rotates as the rotary cylinder 39 rotates.

A partition plate 55 provided near the bottom of the flotation tank 20
A water collection pipe 56 is provided on the lower surface of the water collection pipe 56, and a gauge pipe 57 connected to the water collection pipe 56 is raised to the treated water tank 29 and opened. I'm trying to match it. 5
8 is a drain pipe provided in the treated water tank 29, 59 is a floating object discharge pump installed in the frame 41, and this floating object discharge pump 59 and the suction bow cup 49 are connected to a suction pipe 60.
and are connected via a universal joint 61. 62 is a discharge pipe connected to the sediment removal port 53, and a valve 6
3, and is normally closed.

As shown in FIG. 2, the distribution and dispersion pipe 40 is provided along the radial direction of the flotation tank 20 and is driven to rotate clockwise in the figure by a drive device 44, and a skim rake 51 and a suction pipe are provided at the rear in the rotation direction. A force rough 52 is provided. Further, the skim rake 51 is inclined forward in the rotational direction as it moves away from the suction cup 52 so as to scrape up the floating objects 50 toward the suction cup 52.

In the pressurized flotation separation device 1 2 configured as above, the treated water stored in the treated water tank 29 has a particle size of 1/10 to 1150 by weight relative to the particles contained in the treated raw water.
For example, 2~
It is pressurized to about 4 kg/cm2 and supplied to the pressurized tank 25. Therefore, the pressurized tank 25 stores treated water in which a large amount of air is dissolved.

In the embodiment, air is mixed into the suction side of the pressurized water pump 30 and pressurized together with the treated water, so that the air compression means (near compressor) is omitted, or the treated water and air are independently supplied. It can also be supplied to the pressurized tank 25 after being compressed.

The flow rate of the treated water stored in the pressurized tank 25 is controlled by a flow rate adjustment valve 33, and the treated water is mixed with the medicine sent out from the medicine tank 34 through the medicine supply pump 35 through the pressure reduction valve 31 and the pressurized water supply port 23. It is fed to the bottom of chamber 21. Further, the treated raw water stored in the treated raw water tank 24 is supplied to the bottom of the mixing chamber 21 from the treated raw water supply port 22 with the flow rate controlled by the pump 26 and the flow rate adjustment valve 27, and is supplied from the pressurized water supply port 23. The water is mixed with the pressurized water (becomes water to be treated) and gradually rises in the mixing chamber 21.

Since the mixing chamber 21 is maintained at atmospheric pressure, the air dissolved in the high-pressure treated water supplied from the pressurized water supply port 23 is precipitated as minute bubbles and is contained in the water to be treated. Attach to particles.

The water to be treated that has reached the upper end of the mixing chamber 21 flows out from the outlet 39 formed in the rotary tube 38 together with the particles with air bubbles attached thereto, and the distribution and dispersion pipe rotating clockwise inside the flotation tank 20. The liquid is uniformly supplied to the liquid surface in the flotation tank 20 from the dispersion port 41 of 40 .

Particles contained in the water to be treated supplied to the liquid surface of the flotation tank 20 are quickly separated from the float due to the reduction in specific gravity due to the adhesion of air bubbles. The suction cup 52 is also scraped up by the skim rake 51 which is rotating at the same time, and removed by suction by the floating object discharge pump 59.

Precipitates having a higher specific gravity than water settle at the bottom of the flotation tank 20 and are scraped into the sediment removal port 53 by the raking action of the sediment rake 54. Therefore, only water (treated water) that does not contain floating matter or sediment flows into the water collection pipe 56.
It is supplied to the treated water tank 29 via the gauge pipe 57. In addition,
A part of the treated water supplied to the treated water tank 29 is pressurized by the pressurized water pump 30 as described above and is circulated and supplied to the flotation tank 20 together with air, but the remaining treated water is discharged from the drain pipe 58. Ru.

In the pressurized flotation separation device of the embodiment, the mixing chamber 21 in which solid particles and air bubbles contained in the water to be treated are combined is substantially independent of the flotation tank 20, and the to-be-treated water flowing out from the mixing chamber 21 is made substantially independent of the flotation tank 20. Water is supplied to the liquid surface of the flotation tank 20 from above. Therefore, in the flotation tank 20, only some sinking was observed due to the supply of the water to be treated, but stirring was not performed as in the conventional method, and the sinking of the bubbles was also extremely shallow. For this reason, the required water depth of the flotation tank 20 only needs to be commensurate with the sinking, and since no stirring is performed, the required area is also kept to a minimum.

As an example, in a flotation tank with a surface area of 1 rrf, 2
The maximum sinking depth of bubbles was 30 cm when water to be treated at a rate of 5 m/hour was supplied to the mixing chamber while circulating pressurized water at 5 m/h. Therefore, even if the safety factor was doubled, It is also sufficient to make the effective water depth of the flotation tank 60 cI11 at maximum.

In addition, the calculated required water depth of 0.6 m is given by the following formula.

For this reason, the residence time required for the treatment is 0.6 Required residence time (hours) = 0.0945 minutes, as is clear from the following equation. In other words, the surface area is 1 m' and the effective water depth is 0.
Using a flotation tank with a length of 6 m and a residence time of 5 minutes, the total flow rate is 7 m per hour.
' can now be processed. For this reason, if you want to obtain the same processing capacity, the effective water depth of the flotation tank can be reduced to one-fourth to one-fifth of that of the conventional example, and the flotation tank can be drastically reduced. You can make it smaller.

In the embodiment, the skim rake 51 and the suction force rough 52 are arranged at an angle of approximately 56,270' behind the distribution and dispersion pipe 40 in the rotational direction, or the angle is set at an angle of about 315 to 34, for example.
It is also possible to increase the processing capacity by increasing the angle to about 0° to increase the time lag from dispersing the water to be treated to removing floating objects.

Further, in the embodiment, a part of the treated water is pressurized together with air and circulated and supplied to the flotation tank, thereby preventing wear of the pressurizing pump.

3 and 4 show a second embodiment, in which FIG. 3 is a vertical sectional view of the entire device assembled, and FIG. 4 is a plan view.

The second embodiment also uses a pressurized circulating water system, and the flotation tank is rectangular. A mixing chamber 21 is provided on the side surface of the flotation tank 20 which is formed into a rectangular shape in plan, and the water to be treated flowing out from the mixing chamber 21 is supplied from one end to the liquid surface of the flotation tank 20 using a guide plate 70, A treated water outflow lower 1 and a floating matter discharge lower 2 are provided at the end opposite to the mixing chamber 21. A second skim rake 74 provided on a rotatable conveyor 73 constituted by an endless belt is provided at the top of the flotation tank 20, so that floating objects floating on the water surface are transferred to the second skim rake 74 and floated to the surface. I try to collect the material in the waste discharge lower 2.

Note that the other parts have substantially the same configuration as the first embodiment, so the same reference numerals are given to the parts that perform the same functions, and the explanation thereof is omitted.

(Effects of the Invention) In the present invention, since the water to be treated flowing out from the mixing chamber is supplied to the liquid level of the flotation tank, the supplied water to be treated does not stir the inside of the flotation tank. Therefore, the flotation separation efficiency in the flotation tank is improved, the required surface area and required water depth of the flotation tank can be reduced, and the treatment residence time can also be shortened, resulting in a significant increase in the amount of water treated per unit volume of the flotation tank. This is something that can happen. .

[Brief explanation of drawings]

Figures 1 and 2 show the first embodiment; Figure 1 is a vertical sectional view of the entire device; Figure 2 is a plan view of Figure 1; Figures 3 and 4 are the second embodiment. 3 is a longitudinal sectional view of the entire device, FIG. 4 is a plan view of FIG. 3, and FIG. 5 is an explanatory diagram of the device according to the prior art. 20...Flotation tank 21...Mixing chamber 22.
...Treatment raw water supply port 23...Pressurized water supply port 24.
...Treatment raw water tank 25...Pressure tank 26...
・Pump 27...Flow rate adjustment valve 28...
Flow meter 29... Treated water tank 30... Pressurized water pump 31... Pressure reducing valve 32... Flow meter
33...Flow rate adjustment valve 34...Medical tank
35... Drug supply pump 36... Drug stirring means 37... Air suction port 38... Rotating cylinder
39... Outlet 40... Distribution spray pipe
41... Spraying port 42... Frame 43.
... Drive shaft 44 ... Rotation drive device 45 ... Drive gear 46 ... Followed gear 47 ... Chain 48 ... Seal structure 49 ... Bearing 50 ... Floating object 51 ... Skim rake 52... Suction cup 53... Sediment removal port 9 54... Sediment rake 56... Water collection pipe 58... Drain pipe 60... Suction pipe 63... Valve 70... Guide Plate 72...Floating object discharge port A4...Second skim rake 55-...Partition plate 57...Gauge pipe 59...Floating object discharge pump 61...Universal joint 62...Discharge pipe 71... Treated water outlet a3... Conveyor

Claims (5)

[Claims] (1) A flotation tank, a mixing chamber in which treated raw water and pressurized water are supplied from the bottom, and treated water in which treated raw water and pressurized water are mixed in the mixing chamber, and suspended substances contained in the treated water are attached to air bubbles. a water supply means for supplying treated water from the top of the mixing chamber to the liquid level of the flotation tank; a water collection port for treated water provided at the bottom of the flotation tank; A pressurized flotation separation device comprising a floating object removing means for removing objects, and a water surface height maintaining means for maintaining the water surface height of the flotation tank at a predetermined height. (2) a flotation tank is formed into a circular shape in plan, a cylindrical mixing chamber is provided in the center of the flotation tank, and a horizontal distribution dispersion pipe and a skim rake are rotatably provided in the upper part of the mixing chamber; 2. The pressurized flotation separation apparatus according to claim 1, further comprising a floating object suction cup adjacent to said skim rake and rotatable together with said skim rake. (3) The skim rake is installed on a mounting rod fixed to a rotary tube that is rotatably installed in the upper part of the mixing chamber, and is tilted toward the suction cup so that floating objects are collected against the suction cup. The pressurized flotation separation device according to claim 2, characterized in that: (4) The attachment angle between the distribution and dispersion pipe and the skim rake is such that the skim rake is disposed at an angle of 270° or more at the rear in the rotation direction of the distribution and dispersion pipe. Pressure flotation separation device according to any one of the above. (5) The flotation tank is formed into a planar rectangular shape, a cylindrical mixing chamber is provided on the side of the flotation tank, and a second skim rake provided on an endless belt conveyor is installed above the flotation tank to rotate the conveyor. 2. The pressurized flotation separation device according to claim 1, wherein the pressure flotation separation device is rotatable by movement, and a flotation material discharge port is provided on the opposite side of the mixing chamber in the flotation tank.