JPH09206769A - Downward injecting type ozone treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep a flow rate of a water to be treated subjected to gas-liq. mixing within a fixed range and secure stable ozone treatment by allowing the water to be treated less than a specified flow rate to flow downward in the first flow passage under a constant head difference and allowing the water to be treated above the specified flow rate to flow downward in the second flow passage. SOLUTION: The minimum flow rate of the water to be treated is allowed to flow downward in the first flow passage 8, and the water to be treated above the minimum flow rate is allowed to flow into the second flow passage 11 by interposing the first overflow part 10 and allowed to flow downward. Then the water to be treated which is subjected to gas-liq. mixing by diffusing a gaseous ozone from an ozone diffuser 3 to the water to be treated flowing in the flow passage 9 and the water to be treated flowing in the second flow passage 11 are joined at a joining point 2, and after allowing the jointed water to flow upward in the third flow passage 5, the jointed water is allowed to flow in a residence tank 14 having a partition plate 15 through the second overflow part 13 and discharged from a discharge port 6. And the unreacted ozone out of the gaseous ozone injected in the water to be treated at that time is subjected to the gas-liq. separation at the upper part of the first flow passage 5, and after decomposing at a waste ozone treating device, discharged out of system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone treatment device that sterilizes water to be treated, deodorizes, and oxidizes organic substances, etc. by utilizing the oxidizing effect of ozone.

[0002]

2. Description of the Related Art In recent years, water is used for sterilization, decolorization, deodorization, oxidation removal of organic substances or inorganic substances, etc. by diffusing ozone into water by utilizing the feature that ozone has a strong oxidizing power next to fluorine. The process is widely used. Especially in the water supply in the suburbs of cities, the offensive odor caused by the intake source is widespread, and the strong oxidizing power of ozone described above exerts a great effect in removing the offensive odor. The advanced treatment used is being introduced.

An ozone treatment apparatus for reacting ozone with water to be treated by ozone is an ozone generator for generating ozone from electric energy, a water supply pump for supplying water to be treated, and a reaction for advancing a reaction. Tank,
It consists of waste ozone treatment equipment that decomposes waste ozone discharged unreacted from the reaction tank.As a contact method, a bubble column method in which ozone is blown out as bubbles from the bottom of the reaction tank is generally used. There is. Recently, most of the treatment equipment uses a countercurrent contact method in which the water to be treated is supplied from the top and faces ozone gas in the bubble column.In large-scale water purification plants, etc., multiple countercurrent contact ponds are connected in series. A cross-current countercurrent multi-stage contact pond is used.

[0004] These ozone treatment devices require a contact time for sufficiently performing an oxidation reaction on the water to be treated. Therefore, when the amount of treated water is large, a large-capacity ozone contact basin is required, and when it is introduced into a water treatment plant in the suburbs of a city with a large water supply population, larger-scale equipment is required. I will end up. A large-scale facility is not preferable from the economical point of view and becomes a major factor that hinders the introduction of a treatment apparatus using ozone. Therefore, the ozone reaction tank is required to have a high ozone absorption rate and sufficient removal efficiency.

Here, the ozone absorption rate means that of the injected ozone gas, it is dissolved or decomposed in the water to be treated in the reaction tank.
It is the ratio of ozone consumed and is expressed by the following formula. Ozone absorption rate (%) = (Injected ozone gas concentration-Exhaust ozone gas concentration) / Injected ozone gas concentration x 100 In addition, the removal efficiency is the ratio of water pollutants in the water to be decomposed and removed in the reaction tank. expressed. Typical water pollutants include odorous substances. Removal efficiency (%) = (concentration of inflowing pollutants-concentration of outflowing pollutants)
÷ Influent pollutant concentration × 100 Generally, the higher the ozone absorption rate and removal efficiency, the better the treatment efficiency of the ozone reaction tank.

The amount of ozone transferred when ozone is dissolved in water is the overall mass transfer capacity coefficient (expressed as KLa).
And the difference between the saturated ozone concentration in water and the dissolved ozone concentration (concentration gradient) is the main factor. It is known that this saturated ozone concentration depends on the ozone concentration in the gas and the ozone distribution coefficient. Therefore, it is desirable to make the water depth of the reaction tank as deep as possible from the viewpoint of increasing the ozone dissolution efficiency by utilizing the water depth pressure of the reaction tank, but in the above-mentioned countercurrent contact method, gas is not blown against the water pressure of the reaction tank. Therefore, the actual reactor water depth was 6 m.

Then, a downward injection type ozone treatment apparatus was conceived. FIG. 3 is a schematic view showing a conventional downward injection type ozone treatment device. This downward injection type ozone treatment apparatus introduces the water to be treated from the inlet 1 at the upper part of the reaction tank and at the same time introduces the ozone gas generated by the ozone generator 2 through the ozone diffuser 3. The water to be treated becomes a mixed flow with ozone gas and flows down through the descending dissolution section 4. Next, water is sent from the outlet 6 to the outside of the reaction tank through the ascending section 5A connected at the bottom. The unreacted one of the injected ozone gas is decomposed by the exhaust ozone treatment facility 7 and released into the atmosphere.

In this downward injection type ozone treatment apparatus, since the water to be treated and the ozone gas are introduced from the top at the same time, there is no need to blow the gas against the water depth pressure, and the reaction has a deeper water depth than the countercurrent contact method. The tank can be designed. In addition, since the ozone dissolution rate is fast, the ozone absorption rate is 95% or more, and the organic matter removal efficiency is 75% or more, far exceeding the performance of the countercurrent reactor.

[0009]

However, due to the structure of the downward injection type ozone treatment apparatus, it is necessary to keep the downward flow of gas-liquid mixture stable, and its operating conditions, particularly the flow rate of water to be treated and the flow rate of ozone gas, are restricted. Occurs. Specifically, the flow velocity of the treated water in the downcomer (= the linear velocity of the treated water in the cross sectional area direction of the downcomer) must be kept at 45 cm / s or more, and the ratio of the treated water flow rate to the ozone gas flow rate (the treated water (Flow rate / flow rate of ozone gas) must be maintained at 20 or more. If it is out of this range, lumps of bubbles will occur in the downcomer and the expected processing performance cannot be obtained.

[0010] In water treatment plants in Japan, it is the actual situation that the flow rate of water to be treated generally fluctuates greatly. Therefore, in order to apply the downward injection type ozone treatment equipment to domestic water purification plants, etc., we established a method to respond to fluctuations in the flow rate of treated water and maintain a stable and constant flow velocity of the treated water in the downcomer pipe. There is a need to. Further, in general, the descending melting portion is designed to have a small pipe diameter, which tends to increase the head loss. Therefore, a treated water supply pump may be installed as an auxiliary power for securing the downward flow velocity. This tends to increase the power cost compared to the cross-flow type contact pond which is currently operated by natural flow.

The present invention has been made in view of the above points, and an object thereof is a downward injection type in which the flow velocity of the treated water mixed with gas and liquid is maintained within a certain range regardless of the fluctuation of the flow rate of the treated water and the treatment performance is stable. It is to provide an ozone treatment device. Another object of the present invention is to provide a down-injection type ozone treatment device which can reduce pump power cost when the treated water supply pump is installed in the down-injection type ozone treatment device.

[0012]

According to the first aspect of the present invention, there is provided a first flow path, a second flow path, a third flow path, and
It has a first overflow portion and a second overflow portion, and the first flow path is one in which the water to be treated at a predetermined flow rate or less flows downward in the inside, and ozone gas is generated during the downward flow. The water to be treated is diffused, and the second flow passage is one in which the water to be treated, which has exceeded a predetermined flow rate, flows downward in the inside, and the first flow passage and the second flow passage are mutually connected at the bottom. And the third flow path is a flow path through which the treated water descending through the first flow path and the second flow path merges and flows upward through the inside of the first flow path. Means that the water to be treated overflows from the top of the first flow path to the top of the second flow path, and the second overflow overflows the water to be processed flowing through the third flow path. However, the head of the second overflow is smaller than that of the first overflow.

According to the second invention, in the first invention,
It is effective that the tops of the first and second flow paths are the inflow conduits for the water to be treated, and the flow paths for the water to be processed are connected to the bottoms of the inflow conduits for the first flow channel. . According to the third invention, it is effective that the pump is arranged on the flow pipe in the second invention.

When the minimum flow rate of the water to be treated exceeds the predetermined flow rate, the head of the first overflow portion is larger than the head of the second overflow portion and the difference is constant, so that the first flow path. In this case, the water to be treated at the predetermined flow rate always flows downward. The ozone gas diffused into the water to be treated during the downward flow has a solubility in the water to be treated when it flows down the first channel and reaches the bottom of the first channel with the highest water pressure. It will be maximum.

The water to be treated which has overflowed from the first overflow portion is mixed with the water to be treated which has been allowed to flow downwardly through the first channel when flowing upwardly through the third channel. Reacts with dissolved ozone gas in treated water.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a layout diagram showing a downward injection type ozone treatment apparatus according to an embodiment of the present invention. The water to be treated is introduced into the system through the inlet 1, of which the minimum flow rate of the water to be treated is the inlet channel at the top which is the first channel, and the inlet port 8 which is also the first channel. The flow pipe 9 which is also the first flow path is allowed to flow downward. The water to be treated that exceeds the minimum flow rate flows into the second flow path 11 through the first overflow portion 10 and flows downward. The top of the second flow path serves as an inflow conduit for the water to be treated. Ozone gas from the ozone diffuser 3 is diffused into the water to be treated flowing in the flow pipe 9 which is the first flow path. The water-gas-mixed water to be treated flowing in the flow pipe 9 which is the first flow passage and the water to be treated flowing in the second flow passage 11 merge at a confluence point 12 and rise in the third flow passage 5. After passing through the second overflow portion 13, it flows through the retention tank 14 having the partition plate 15 and is discharged from the discharge port 6.

The flow velocity of the water to be treated in the flow pipe 9 which is the first flow path is kept constant by the difference between the head of the first overflow portion and the head of the second overflow portion. Therefore, the head difference between the first overflow portion and the second overflow portion, the pipe diameter of the flow pipe 9, and the flow rate distributed to the second flow passage 11 are designed based on the minimum treated water amount assumed in advance. If it is set, even if the amount of water to be treated increases, the increase will all flow to the second flow path, and the flow rate in the flow pipe 9 will be maintained constant.

As shown in the figure, a partition plate 15 is installed in the retention tank 14 to form a vertical bypass structure so that the flow of water in the retention tank 14 becomes uniform and the occurrence of a short circuit flow is suppressed. It
Further, the residence time in the retention tank 14 is required to allow the decomposition reaction of organic substances and the like to proceed, and is set to about 10 to 20 minutes for the purpose of removing odorous substances and the like. Unreacted ozone gas injected into the water to be treated is gas-liquid separated in the upper part of the first flow path 5, decomposed by the exhaust ozone treatment equipment 7, and discharged to the outside of the system.

When the flow rate in the flow pipe 9 cannot be maintained only due to the head difference, a treated water supply pump 16 is installed as an auxiliary power. The tops of the first and second flow passages are treated water inlets, and when the treated water flow pipe is connected to the bottom of the inlet of the first flow passage, the treated water flows. Ozone gas can be diffused into the pipe, and the overflow of the water to be treated in the first overflow portion and the dissolution of the ozone gas in the water to be treated in the first flow path proceed efficiently.

FIG. 2 is a layout view showing a downward injection type ozone treatment apparatus according to another embodiment of the present invention. The untreated water supply pump 16 is installed on the flow pipe 9. When the pump is arranged on the flow pipe, auxiliary power is applied in the downward flow direction of the water to be treated, so that the increase in power cost is reduced.

[0021]

According to the present invention, the water to be treated having a predetermined flow rate or less is caused to flow downward through the first flow path under a constant head difference, and the water to be treated exceeding the predetermined flow rate is supplied to the second flow path. Therefore, when the minimum treated water flow rate exceeds the predetermined flow rate, the predetermined flow rate of the treated water always flows through the first flow path even if the flow rate of the treated water changes. It is possible to obtain a downward injection type ozone treatment apparatus in which ozone treatment is stable by maintaining the flow velocity of water to be treated mixed with gas and liquid within a certain range.

When the pump is arranged on the flow pipe, the auxiliary power is applied in the downward flow direction of the water to be treated, so that the auxiliary power is reduced and a highly efficient ozone treatment system which has never been obtained can be obtained.

[Brief description of drawings]

FIG. 1 is a layout view showing a downward injection type ozone treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a layout view showing a downward injection type ozone treatment apparatus according to another embodiment of the present invention.

FIG. 3 is a schematic view showing a conventional downward injection type ozone treatment device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 introduction port 2 ozone generator 3 ozone diffuser 4 descending dissolution part 5A rising part 5 third flow path 6 discharge port 7 waste ozone treatment device 8 first flow path (inlet) 9 first flow path ( Flow pipe) 10 First overflow part 11 Second flow path 12 Confluence point 13 Second overflow part 14 Retention tank 15 Partition plate 16 Pump

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C02F 1/50 540 C02F 1/50 540A 550 550H 1/58 1/58 A

Claims (3)

[Claims] 1. A first flow path, a second flow path, a third flow path, a first overflow part, and a second overflow part, wherein the first flow path is The water to be treated flows below a prescribed flow rate, and ozone gas is diffused into the water to be treated during the downward flow. The first flow passage and the second flow passage are connected to each other at their bottoms, and the third flow passage descends the first flow passage and the second flow passage, respectively. The treated water that has flowed through merges and flows upward through the inside, and the first overflow portion overflows the treated water from the top of the first channel to the top of the second channel. The second overflow is the water to be treated that has flowed through the third flow path, and the head of the second overflow is higher than that of the first overflow. Downward infusion characterized by being small Ozone processing apparatus. 2. The downward pouring type ozone treatment apparatus according to claim 1, wherein the tops of the first and second flow paths are the inflow conduits of the water to be treated, and the bottoms of the inflow conduits of the first flow path. Is a down-injection type ozone treatment device, characterized in that a flow pipe for the water to be treated is connected. 3. The down-injection ozone treatment device according to claim 2, wherein a pump is arranged on the flow pipe.