JP2020189273A - Ozone contact reaction tank - Google Patents

Abstract

To provide an ozone contact reaction tank capable of effectively separating ozone treated water from fine bubbles in a gas-liquid separation part.SOLUTION: The ozone contact reaction tank includes a descending flow channel 13 in which the treated water descends, an ascending flow channel 14 in which the treated water rises through the lower end of the descending flow channel, and a gas-liquid separation part 17 at the upper end of the ascending flow channel, with an inlet 15 of treated water and an ozone inlet 16 at the upper end of the descending flow channel, and a gas-liquid separation part 17 with an overflow weir 17a at the upper end of the ascending flow channel. It has a treated water outflow part 19 at the bottom of the gas-liquid separation part 17 via the treated water storage part 17b, and the gas discharge part 20 is provided at the top, and a treated water collision member 23, with which the ozone treated water 22 falling over the overflow weir collides with the treated water storage part is installed on an outer surface of the ascending flow channel.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ozone contact reaction tank, and more particularly to an ozone contact reaction tank provided with a gas-liquid separation unit that separates ozone (ozone-containing gas) injected into the water to be treated from the ozone-treated water.

As an ozone contact reaction tank used for various water treatments, especially advanced water purification treatment of clean water, ozone gas in the water to be treated flowing into the flow pipe, usually ozone-containing oxygen obtained by ozoneizing a part of oxygen by silent discharge. Is injected, ozone is dissolved in the water to be treated by utilizing the increase in water pressure caused by the water to be treated accompanied by ozone gas descending in the descending flow path, and the dissolved ozone removes organic compounds in the water to be treated. Those that promote the effect of oxidizing, decomposing and removing the target substance are known.

As a specific example of such an ozone contact reaction tank, as shown in FIG. 4, the inside of the inner pipe 11 of the double pipe composed of the inner pipe 11 and the outer pipe 12 made of metal or concrete communicating at the folded portion at the lower end is formed. The descending flow path 13, between the inner pipe 11 and the outer pipe 12 is an ascending flow path 14, and the water to be treated water inflow portion 15 and the ozone injection portion 16 are provided at the upper end portion of the inner pipe 11, and the upper end of the outer pipe 12 is provided. An ozone contact reaction tank having a double-tube structure in which a gas-liquid separation portion 17 is provided so as to surround the portions is used (see, for example, Patent Document 1). Normally, an activated carbon adsorption pond 18 for filtering the ozone-treated water separated by the gas-liquid separation unit 17 is provided in the subsequent stage of the ozone contact reaction tank, and the treated water outflow unit 19 of the gas-liquid separation unit 17 is provided. The ozone-treated water discharged from the ozone-treated water is filtered, and the ozone-containing gas separated by the gas-liquid separation unit 17 is discharged from the gas discharge unit 20 to the gas treatment unit to detoxify the ozone.

Japanese Patent No. 3648352

The gas-liquid separation unit 17 described in Patent Document 1 uses the upper end of the outer pipe 12 as an overflow weir 17a, and the supersaturated ozone-treated water (bubbles that can be visually recognized as bubbles from the outside) that has risen in the ascending flow path 14. Millibubbles) and ozone-treated water in which ozone-containing gas is excessively dissolved) are dropped from the upper end of the overflow weir 17a onto the ozone-treated water stored in the treated water storage section 17b provided at the bottom of the gas-liquid separation section 17. Therefore, a large amount of millibubbles mixed in the ozone-treated water and fine bubbles (microbubbles) generated by being released from hypersaturation by dropping were mixed. Furthermore, the rise of bubbles is hindered by the new ozone-treated water that has fallen, and the microbubbles with a slow terminal velocity in the ozone-treated water do not surface or disappear, and the activated carbon adsorption pond 18 is mixed with the hypersaturated ozone-treated water. Will be sent.

Therefore, when the microbubbles in the ozone-treated water flow through the gap between the activated carbons in the activated carbon adsorption pond 18, the microbubbles in the ozone-treated water are trapped in the gap, and the supersaturated ozone-treated water is supplied to promote the growth of the microbubbles. , A bubble layer was sometimes generated in the activated carbon layer. When a bubble layer was generated in the activated carbon layer, the filtration resistance in the activated carbon adsorption pond 18 increased, which was a factor of increasing the head loss of the activated carbon adsorption pond 18. Therefore, there is a problem that the water treatment must be interrupted and the degassing step of the activated carbon adsorption pond 18 must be performed.

Therefore, the present invention can effectively separate ozone-treated water and fine bubbles in the gas-liquid separation section, and in the gas-liquid separation section, particularly in the activated carbon adsorption pond, which does not adversely affect the treatment in the subsequent stage. It is an object of the present invention to provide an ozone contact reaction tank capable of preventing the generation of a bubble layer.

In order to achieve the above object, the ozone contact reaction tank of the present invention has a descending flow path in which the water to be treated descends, an ascending channel in which the water to be treated rises by communicating with the lower end of the descending flow path, and the ascending flow path. It is provided with a gas-liquid separation portion provided at the upper end of the flow path, an inflow portion of water to be treated and an ozone injection portion are provided at the upper end portion of the descending flow path, and an overflow is provided at the upper end portion of the ascending flow path. In an ozone contact reaction tank in which a gas-liquid separation section having a dam is provided, a treated water outflow section is provided below the gas-liquid separation section via a treated water storage section, and a gas discharge section is provided above the gas-liquid separation section. The treated water storage unit is characterized in that a treated water collision member with which ozone treated water falling over the overflow dam collides with the treated water storage portion is provided on the outer surface of the ascending flow path.

Further, in the ozone contact reaction tank of the present invention, the height of the upper surface of the treated water collision member is set flush with respect to the water surface in the treated water storage portion, or the tip from the base portion on the overflow weir side. It is characterized by having a water gradient toward. Further, the treated water collision member is characterized in that it is formed of concrete, a metal plate, or a perforated metal plate.

According to the ozone contact reaction tank of the present invention, the oversaturation of the treated water is eliminated by the energy when the ozone-treated water falling over the overflow dam collides with the treated water collision member, and the dropped ozone-treated water is eliminated. Since it does not flow into water, microbubbles are less likely to exist as bubbles, so that ozone-treated water in a state in which almost no bubbles are present can be obtained. Therefore, it is possible to prevent the formation of a bubble layer in the activated carbon adsorption pond in the subsequent stage and prevent the head loss from rising.

It is sectional drawing of the main part which shows the 1st form example of the ozone contact reaction tank of this invention. It is sectional drawing of the main part which shows the 2nd form example of the ozone contact reaction tank of this invention. It is sectional drawing of the main part which shows the 3rd form example of the ozone contact reaction tank of this invention. It is a system diagram which shows an example of the conventional ozone contact reaction tank.

FIG. 1 is a cross-sectional view of a main part showing an example of the first embodiment of the ozone contact reaction tank of the present invention. In the following description, the same components as the components of the ozone contact reaction tank shown in FIG. 4 will be designated by the same reference numerals, and detailed description thereof will be omitted.

The ozone contact reaction tank 21 shown in this embodiment has basically the same configuration as the conventional one, and the upper end of the outer tube 12 is placed on the upper part of the double tube composed of the inner tube 11 and the outer tube 12. A gas-liquid separation unit 17 is provided so as to surround the gas-liquid separation unit 17. The upper part of the inner pipe 11 penetrates the top plate of the gas-liquid separation part 17, and the water to be treated water inflow part 15 and the ozone injection part 16 are provided at the upper end part.

The gas-liquid separation unit 17 is formed in a cylindrical shape coaxial with the outer tube 12, and ozone-treated water from which bubbles have been separated is extracted from the bottom plate and sent to a subsequent facility, for example, an activated carbon adsorption pond (not shown). A treated water outflow section 19 is provided for this purpose, and a gas discharge section 20 is provided on the top plate for extracting the separated gas (ozone-containing gas) and sending it to the ozone detoxification treatment facility. Immediately after the treated water outflow section 19, a weir or the like for keeping the surface of the treated water stored in the treated water storage section 17b constant is provided.

A treated water collision member 23 for colliding the supersaturated ozone-treated water 22 that falls over the overflow weir 17a formed at the upper end of the outer pipe 12 is provided on the upper outer periphery of the outer pipe 12. The treated water collision member 23 is integrally formed with the outer pipe 12 in a ring shape by concrete, and the inner peripheral portion is in contact with the outer peripheral surface of the outer pipe 12, and the outer peripheral portion and the gas-liquid separation portion 17 A space serving as a flow bottom 24 is provided between the inner peripheral surface and the inner peripheral surface. Further, the upper surface of the treated water collision member 23 is arranged in the horizontal direction so as to be flush with the set water surface of the treated water stored in the treated water storage portion 17b below the gas-liquid separation portion.

In the ozone contact reaction tank 21, the ozone-containing gas injected into the water to be treated at the upper part of the inner pipe 11 is press-fitted into the water due to the pressure increase when flowing down the descending flow path 13 in the inner pipe 11 to 10 m or more. The substance to be removed in the water to be treated reacts with ozone to be oxidized, decomposed and removed. After that, as the pressure drops when ascending the ascending flow path 14 between the inner pipe 11 and the outer pipe 12, an unstable supersaturated state is reached, and the impact when flowing through the ascending flow path causes millibubbles and supersaturated ozone-treated water. Will be in a mixed state. Large-diameter bubbles, for example, millibubbles (bubble particle size of 100 μm or more) that can be visually recognized as bubbles from the outside, rise and disappear at the upper end of the ascending flow path 14 due to their own levitation force, and become gas and are discharged from the gas discharge unit 20. Will be done. At this time, from the viewpoint of solubility in water, oxygen in the ozone-containing gas is more unstable in a dissolved state than ozone, and oxygen is a main factor for generating bubbles.

On the other hand, some of the microbubbles (bubble size of about 1 to 100 μm) are redissolved and disappear, and the other part grows and rises and disappears, but most of the bubbles cross the overflow weir 17a. , It falls toward the treated water collision member 23. The supersaturated ozone-treated water 22 that has fallen on the upper surface of the treated water collision member 23 is released from the supersaturated state by the energy when it collides with the treated water collision member 23, and there is no water surface on the upper surface of the treated water collision member 23. Since the ozone-treated water 22 does not flow into the water, microbubbles are less likely to exist as bubbles, and are discharged from the ozone-treated water in the same manner as the bubbles having a millibubble or more.

As a result, the treated water storage unit 17b is in a state in which ozone-treated water with reduced microbubbles is stored. In this way, by eliminating the microbubbles, which are a major cause of generating a bubble layer in the activated carbon adsorption pond in the subsequent stage, from the ozone-treated water, the generation of the bubble layer in the activated carbon adsorption pond is prevented and the head loss rises. Can be prevented. Therefore, it is not necessary to perform the degassing step of the activated carbon adsorption pond, and the water treatment efficiency can be improved.

On the other hand, ultrafine bubbles (bubble size of 1 μm or less), whose existence cannot be visually recognized from the outside, flow out from the treated water outflow section 18 in a state of being dispersed in the ozone-treated water, but because they are stagnant in the water. No bubble layer is generated in the activated carbon adsorption pond.

Further, by providing such a treated water collision member 23, new ozone-treated water that has crossed the overflow weir 17a flows in the outer peripheral direction on the upper surface of the treated water collision member 23, and the gas-liquid separation unit 17 smoothly. Since it flows into the surface portion of the ozone-treated water stored in the lower part, it is possible to prevent the generation of new bubbles without generating a complicated flow in the stored ozone-treated water.

FIG. 2 is a cross-sectional view of a main part showing a second embodiment example of the ozone contact reaction tank of the present invention. In this embodiment, a ring-shaped metal plate having an opening 25a corresponding to the outer diameter of the outer pipe 12 on the inner peripheral portion, for example, a treated water collision member 25 formed of a steel plate is stored in the lower part of the gas-liquid separation portion 17. It is installed so that it is flush with the set water surface of the treated water. Further, a cheek cane 25b for ensuring the strength of the treated water collision member 25 is provided between the lower surface of the treated water collision member 25 and the outer peripheral surface of the outer pipe 12.

By providing such a metal treated water collision member 25, the same action and effect as the concrete treated water collision member 23 shown in the first embodiment can be obtained, and the treated water outflow portion 19 can be used. It is possible to eliminate fine bubbles (microbubbles) in the ozone-treated water to be sent out.

FIG. 3 is a cross-sectional view of a main part showing a third embodiment example of the ozone contact reaction tank of the present invention. In this embodiment, the treated water collision member 26 using a metal perforated plate having a large number of through holes 26a is provided so as to cover the entire surface of the ozone-treated water stored in the lower part of the gas-liquid separation portion 17. The supersaturated ozone-treated water that falls over the overflow dam 17a is eliminated by the energy generated when it collides with the treated water collision member 26, and the ozone-treated water has no water surface on the upper surface of the member 26 and flows into the water. Therefore, it is difficult for fine bubbles to be generated, and the ozone-treated water passes through a large number of through holes 26a of the treated water collision member 26 and flows down to the lower part of the gas-liquid separation unit 17.

The size of the through hole 26a in the treated water collision member 26 is such that the ozone treated water does not stay on the treated water collision member 26 due to surface tension, and the ozone treated water dropped from the overflow dam 17a has an appropriate collision energy. It suffices to set so that the water can be given, and the through-holes in the inner peripheral part where the fallen ozone-treated water collides are made small, and the through-holes in the outer peripheral part are made large to optimize the collision energy and flowability. You can also. Further, it is also possible to arrange a non-perforated plate on the inner peripheral side and a perforated plate on the outer peripheral side.

The structure of the ozone contact reaction tank is not limited to the structure of each of the above examples, and various structures can be adopted, and the equipment at the subsequent stage is also optional. Further, in order to prevent the ozone-treated water from staying on the upper surface of the treated water collision member, the upper surface of the treated water collision member is slightly inclined from the base on the overflow weir side toward the outer peripheral end of the treated water storage part. A water gradient can also be provided.

11 ... Inner pipe, 12 ... Outer pipe, 13 ... Downstream, 14 ... Upstream, 15 ... Water inflow part to be treated, 16 ... Ozone injection part, 17 ... Gas-liquid separation part, 17a ... Overflow dam, 17b ... Treated water storage part, 18 ... Activated carbon adsorption pond, 19 ... Treated water outflow part, 20 ... Gas discharge part, 21 ... Ozone contact reaction tank, 22 ... Ozone treated water, 23 ... Treated water collision member, 24 ... Flowing down, 25 ... Treated water collision member, 25a ... Opening, 25b ... Cheek cane, 26 ... Treated water collision member, 26a ... Through hole

Claims (6)

It is provided with a descending flow path in which the water to be treated descends, an ascending flow path in which the water to be treated rises by communicating with the lower end of the descending flow path, and a gas-liquid separation portion provided at the upper end of the ascending flow path. An inflow portion of water to be treated and an ozone injection portion are provided at the upper end of the descending flow path, and a gas-liquid separation portion having an overflow dam is provided at the upper end of the ascending flow path, and the gas-liquid separation is provided. In an ozone contact reaction tank in which a treated water outflow section is provided at the lower part of the section via a treated water storage section and a gas discharge section is provided at the upper part, ozone that falls into the treated water storage section over the overflow dam. An ozone contact reaction tank characterized in that a treated water collision member with which the treated water collides is provided on the outer surface of the ascending flow path. The ozone contact reaction tank according to claim 1, wherein the height of the upper surface of the treated water collision member is set flush with respect to the set water surface in the treated water storage unit. The ozone contact reaction tank according to claim 1, wherein the treated water collision member has an upper surface having a water gradient from a base portion on the overflow weir side toward the tip end. The ozone contact reaction tank according to any one of claims 1 to 3, wherein the treated water collision member is made of concrete. The ozone contact reaction tank according to any one of claims 1 to 3, wherein the treated water collision member is formed of a metal plate. The ozone contact reaction tank according to any one of claims 1 to 3, wherein the treated water collision member is formed of a perforated metal plate.

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