JP3526362B2 - Downward injection type ozone treatment equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone treatment apparatus for sterilizing, deodorizing, and oxidizing organic substances in water to be treated by utilizing the oxidizing action of ozone. [0002] In recent years, utilizing the feature that ozone has a strong oxidizing power next to fluorine, ozone is diffused into water to sterilize, decolorize, deodorize, oxidize and remove organic or inorganic substances, and the like. Water treatment is widely performed. In particular, in the water supply near the city, the damage of the off-flavor due to the water intake source is widespread, and the strong oxidizing power of ozone described above exerts a great effect on removing this off-flavor. Introduction of advanced processing used is being promoted. [0003] Such 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 pump for supplying the water to be treated, and a reaction for proceeding the reaction. Tank,
It is composed of waste ozone treatment equipment that decomposes exhausted ozone discharged unreacted from the reaction tank, and as a contact method, a bubble column method in which ozone is blown out as bubbles from the lower part of the reaction tank is generally used. I have. Recently, most treatment equipment uses a countercurrent contact system in which the water to be treated is supplied from the top and faces the ozone gas in the bubble column. In large-scale water purification plants, etc., multiple countercurrent contact ponds are connected in series. A crossflow type countercurrent multistage contact pond is used. [0004] These ozone treatment apparatuses require a contact time sufficient to sufficiently perform an oxidation reaction on the water to be treated. Therefore, large volume ozone contact ponds are required when the treated water volume is large, and larger scale facilities are required when introducing them to water purification plants near urban areas with a large population of water supply. I will. Large-scale equipment is not preferable from the viewpoint of economy, and is a major factor that hinders introduction of a treatment apparatus using ozone. Therefore, an ozone reaction tank is required to have a high ozone absorption rate and a sufficient removal efficiency. [0005] Here, the ozone absorptivity means that the injected ozone gas is dissolved or decomposed in the water to be treated in the reaction tank.
It is the ratio of consumed ozone and is expressed by the following equation. Ozone absorption rate (%) = (injected ozone gas concentration-exhausted ozone gas concentration) ÷ injected ozone gas concentration x 100 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 (%) = (Inflow pollutant concentration-Outflow pollutant concentration)
÷ Inflow pollutant concentration x 100 Generally, the higher the ozone absorption rate and removal efficiency, the better the treatment efficiency of the ozone reactor. [0006] The amount of ozone transfer when ozone is dissolved in water is determined by the overall mass transfer capacity coefficient (denoted as KLa).
And the difference (concentration gradient) between the saturated ozone concentration in water and the dissolved ozone concentration. It is known that the saturated ozone concentration depends on the ozone concentration in the gas and the ozone distribution coefficient. Therefore, from the viewpoint of increasing the ozone dissolution efficiency by using the water depth pressure of the reaction tank, it is desirable to set the water depth of the reaction tank as deep as possible, but in the above-described countercurrent contact method, gas is not blown against the reaction tank water depth. The actual depth of the reactor tank was limited to 6m because it was not possible. What has been devised is a downward injection type ozone treatment apparatus. FIG. 3 is a schematic diagram showing a conventional downward injection type ozone treatment apparatus. In this downward injection type ozone treatment apparatus, water to be treated is introduced from an introduction port 1 in the upper part of the reaction tank, and at the same time, ozone gas generated by an ozone generator 2 is introduced through an ozone diffuser 3. The water to be treated becomes a mixed flow with the ozone gas and flows down the descending dissolution unit 4. Next, water is sent from the outlet 6 to the outside of the reaction tank via the rising portion 5A connected at the bottom. The unreacted one of the injected ozone gas is decomposed by the waste ozone treatment equipment 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 simultaneously from the top, there is no need to blow gas against the water depth pressure, and the reaction has a deeper water depth than the countercurrent contact type. Tank design is possible. In addition, since the dissolution rate of ozone is high, the ozone absorption rate is 95% or more, and the organic matter removal efficiency is 75% or more. However, the down-injection type ozone treatment apparatus needs to maintain a stable downflow of gas-liquid mixture due to its structure, and its operating conditions, particularly the flow rate of the water to be treated and the flow rate of ozone gas Has restrictions. Specifically, the velocity of the water to be treated in the downcomer (= the linear velocity of the treated water in the direction of the cross-sectional area of the downcomer) must be maintained at 45 cm / s or more, and the ratio of the flow rate of the treated water to the flow rate of the ozone gas (the treated water) (Flow rate ozone gas flow rate) needs to be maintained at 20 or more. Outside this range, bubbles may form in the downcomer and the expected processing performance may not be obtained. In a water purification plant in Japan, the flow rate of the water to be treated generally fluctuates drastically. Therefore, in order to apply the downward injection type ozone treatment system to water treatment plants in Japan, etc., a method has been established to constantly and stably maintain the flow rate of the water in the downcomer within a certain range in response to fluctuations in the flow rate of the water to be treated. There is a need to. In addition, since the descending melting part is generally designed to have a small pipe diameter, the head loss tends to increase. Therefore, a treated water supply pump may be installed as an auxiliary power for securing the descending flow velocity. This is likely to result in increased power costs compared to a cross-flow pond currently operating by gravity. SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to maintain the flow rate of gas-liquid mixed water to be treated within a certain range irrespective of fluctuations in the flow rate of the water to be treated, and to provide a downward injection type with a stable treatment performance. An object of the present invention is to provide an ozone treatment device. It is another object of the present invention to provide a downward injection type ozone treatment apparatus capable of reducing pump power cost when a water supply pump is installed in a downward injection type ozone treatment apparatus. According to the present invention, a first flow path, a second flow path, a third flow path, and a first overflow are provided. the flow section has a second overflow section, the first flow channel always treated water is lowered through flow inside which is a constant predetermined flow rate, the ozone gas is treated in closed descending through flow is aeration in water, treated water in the second flow path exceeds a predetermined flow rate inside lowered through flow, a first flow passage and the second flow path are coupled to each other at respective bottoms, The water to be treated, which has flowed downward through the first flow path and the second flow path, respectively, merges into the third flow path , and flows upward inside the first flow path. the treated water is overflowed to the second channel, the second overflow portion is overflow water to be treated flows through the third flow passage, the water head of the second overflow section first Smaller than the head of the overflow There are, by the difference between the first overflow of water head and a second overflow portion of water head, by maintaining the water to be treated inside the first flow path <br/> constant flow constant at Achieved. When the minimum flow rate of the water to be treated exceeds the predetermined flow rate, the head of the first overflow is larger than the head of the second overflow, and the difference is constant. In the flow path, the water to be treated having the predetermined flow rate always flows downward. The ozone gas diffused into the water to be treated on the way to the downward flow flows downward through the first flow path, and when reaching the bottom of the first flow path with the highest water pressure, the solubility in the water to be processed is reduced. Be the largest. The water to be treated which has overflowed the first overflow portion is mixed with the water to be treated which has flowed downward through the first flow path when flowing upward through the third flow path. Reacts with dissolved ozone gas in treated water. 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 from the inlet 1, and the minimum flow rate of the water to be treated is the first inflow culvert, which is the first flow path, the inflow port 8, which is also the first flow path, and The flow pipe 9 which is also the first flow path flows downward. The water to be treated exceeding the minimum flow rate flows into the second flow path 11 via the first overflow section 10 and flows downward. The top of the second channel is an inflow channel for the water to be treated. Ozone gas from the ozone diffuser 3 is diffused into the water to be treated flowing through the flow pipe 9 as the first flow path. The gas-liquid mixed water to be processed flowing through the flow pipe 9 as the first flow path and the water to be processed flowing through the second flow path 11 merge at a junction 12 and rise in the third flow path 5. The water flows through the second overflow portion 13, flows through the retention tank 14 having the partition plate 15, and is discharged from the discharge port 6. The flow rate 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 and the head of the second overflow. Therefore, the head difference between the first overflow portion and the second overflow portion, the pipe diameter of the flow pipe 9, and the distribution flow rate to the second flow path 11 are designed based on the assumed minimum treated water amount. In this case, even if the amount of water to be treated increases, all of the increase flows to the second flow path, and the flow rate in the flow pipe 9 is kept constant. As shown in the figure, if a partition plate 15 is provided in the storage tank 14 to form a vertical detour structure, the flow of water in the storage tank 14 becomes uniform, and the occurrence of short-circuit flow is suppressed. You.
The residence time in the residence tank 14 needs to be long enough to allow the decomposition reaction of organic substances and the like to proceed. For example, when the purpose is to remove odorous substances and the like, the residence time is set to about 10 to 20 minutes. Among the ozone gas injected into the water to be treated, unreacted ozone gas is separated into gas and liquid in the upper part of the first flow path 5, decomposed by the waste ozone treatment equipment 7, and released out of the system. When the flow rate in the flow pipe 9 cannot be maintained only by the head difference, a water supply pump 16 is installed as auxiliary power. The top of each of the first and second flow paths is an inflow channel for the water to be treated. When the flow pipe of the water to be treated is connected to the bottom of the inflow channel of the first flow path, the flow of the water to be treated is The ozone gas can be diffused in the pipe, and the overflow of the water to be treated in the first overflow portion and the dissolution of the ozone gas into the water to be treated in the first flow passage proceed efficiently. FIG. 2 is a layout diagram showing a downward injection type ozone treatment apparatus according to another embodiment of the present invention. A to-be-treated water supply pump 16 is provided 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. According to the present invention, the water to be treated having a flow rate equal to or less than a predetermined flow rate is caused to flow down the first flow path with a fixed head difference, and the water to be treated exceeding the predetermined flow rate is reduced to a second flow rate. When the minimum flow rate of the water to be treated exceeds the predetermined flow rate, the first flow path always has the predetermined flow rate of the water to be treated even if the flow rate of the water to be treated fluctuates. Flows, and the flow rate of the gas-liquid mixed water to be treated is maintained within a certain range, whereby a downward injection type ozone treatment apparatus with stable ozone treatment can be obtained. When a 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 auxiliary power is reduced, and an unprecedented high-efficiency ozone treatment system is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a layout diagram showing a downward injection type ozone treatment device according to an embodiment of the present invention. FIG. 2 is a layout diagram showing a downward injection ozone treatment device according to a different embodiment of the present invention. FIG. 3 is a schematic view showing a conventional downward injection type ozone treatment apparatus. [Description of References] 1 Inlet 2 Ozone generator 3 Ozone diffuser 4 Down melting part 5A Up part 5 Third flow path 6 Outlet 7 Exhaust ozone treatment device 8 First flow path (inlet) 9 First flow path (flow pipe) 10 First overflow section 11 Second flow path 12 Junction point 13 Second overflow section 14 Retention Vessel 15 Partition plate 16 Pump

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-85096 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/78 B01F 1/00 C02F 1 / 50

Claims (1)

(57) [Claims 1] A first flow path, a second flow path, a third flow path, a first overflow section, and a second overflow section. a, wherein the first flow path, always treated water is lowered through flow inside which is a constant predetermined flow rate, the air diffuser ozone gas in the water to be treated in closed descending through flow, the first the second flow path, the water to be treated exceeds a predetermined flow rate is lowered through flow therethrough, said second flow path and the first flow path are coupled to each other at respective bottoms, said first the third flow path, an internal increased through-flow said first flow path and the second flow path joins said treatment water flowed respectively lowered through the first overflow portion, the water to be treated exceeds a predetermined flow rate is overflow in the second flow channel, said second overflow section to overflow the water to be treated flows through the third flow passage, the second The head of the overflow area is the first It is those smaller than the water head of the flow unit, the difference between the said and the first overflow portion of the water head second overflow portion of water head, the water to be treated inside the first flow path A downward injection type ozonation apparatus characterized by maintaining a constant predetermined flow rate.