JPH1110175A - Control method of pressurized type downward injection ozone contact tank - Google Patents

Abstract

(57) [Problem] To perform water quality control of an ozone contact tank, various indices such as dissolved ozone concentration and water quality (UV value) are considered in principle. However, at present, many of these sensors are unstable (low in reliability), so that stable water quality control was not possible. SOLUTION The present invention realizes ozone injection amount control without using a sensor. Ozone injection rate controller 17
In, and calculates the injection ozone concentration target value P _in the following equation. P _in = D _SET × Q / Q _G (D _SET : ozone injection rate set value,
Q: treatment water flow rate, Q _G: The ozone flow rate) injecting ozone concentration controller 18 calculates the power value by injecting ozone concentration target value P _in the injection of ozone concentration, and controls the ozone generation amount of the ozone generator 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an ozone contact tank, and more particularly to a method for controlling the water quality of a pressurized downward injection ozone contact tank at a constant level.

[0002]

2. Description of the Related Art At present, a treatment method using ozone gas has attracted attention as a treatment method in water supply and sewerage. This ozone has a very strong oxidizing and sterilizing power as compared with chlorine, and is used for the purpose of removing trace harmful substances, odors, bacteria, etc. in water. However, ozone gas costs about twice as much as chlorine production, so in order to use ozone gas without waste, it is necessary to dissolve ozone gas in water efficiently and to use appropriate ozone gas according to the amount of ozone removal target substance. Infusion is an important factor.

Generally, ozone gas is efficiently dissolved in water.
As a method of making contact, an air diffuser method and a deep U-tube method are known. The former uses ozone gas of several tens of μm.
Air bubbles are generated and blown into the water through a diffuser tube made of ceramic or the like having fine pores. In a water purification plant, this is shown in FIG. It is used as a vertical detour type.

[0006] In FIG. 6, reference numeral 60 denotes an ozone contact tank. The inside of the ozone contact tank 60 is divided by a pair of partition walls 61, 62 to form a plurality of reaction chambers 63 a, 63 b, 63 c. A pair of partitions 61 and 62 form a flow path on one side, and a partition 62 forms a flow path above to divert the water to be treated as shown by the dotted line.

[0005] Numerals 64a, 64b and 64c are diffuser tubes having a large number of fine holes. Ozone gas is sent from an ozone generator (not shown) into each of the reaction chambers 63a, 63b and 63c to oxidize harmful substances in the water to be treated. After the reaction, ozone treatment is performed. The water to be treated is supplied from the upper part of the reaction tank 13a, and the treated water subjected to the ozone treatment is sent from the lower part of the reaction tank 63c.

As described above, in the air diffuser system, the ozone gas is released into the water to be treated from the fine holes of the air diffuser, so that the air diffuser is clogged by iron, manganese, etc. contained in the water to be treated, Over time, the ozone dissolution rate decreases, necessitating replacement of the air diffuser.

[0007] Further, the air diffusion layer type ozone contact layer has a multi-stage contact layer structure in which a plurality of reaction layers are passed in order to secure an ozone reaction time, so that it becomes large and secures land at a water purification plant near a city. Becomes difficult.

Therefore, attention has been paid to a deep U-tube system without using an air diffuser. FIG. 7 is a schematic diagram of this deep U-tube system. As shown in FIG.
It has a double tube structure. That is, reference numeral 71 denotes an outer tube of a vertically long ozone contact tank, and an inner tube 72 is provided in the inside thereof in a vertical direction. Ozone gas obtained by the ozone generator 73 is fed into the inner pipe 72 from above via an ozone gas feed pipe 74. Further, a water to be treated feed pipe 75 is communicated with the inner pipe 72 to supply the water to be treated.

The water to be treated with ozone flows in from the upper part of the inner pipe 72, descends and rises from the lower outlet 72 a of the inner pipe 72 to the upper part of the outer pipe 71, and is treated through the upper treated water tank 76. It flows out through the water delivery pipe 77.

At this time, the ozone gas is also blown from the upper part of the inner pipe 72 in the same direction as the water to be treated, flows together with the water to be treated toward the lower part of the inner pipe 72, and rises from the lower outlet 72a. The water and the ozone gas are continuously contacted and dissolved in the inner tube, and an oxidation reaction between the dissolved ozone and harmful substances in the water to be treated occurs, thereby performing a desired ozone treatment.

At this time, the unreacted ozone gas (bubbles)
The wastewater is sent to a waste ozone treatment device 79 via a non-ozone gas delivery pipe 78 provided in a treated water tank 76 and is subjected to a cleaning treatment.

This U-tube type ozone contact tank promotes gas-liquid contact between the ozone gas and the water to be treated by turbulent flow generated in the inner tube, and increases the water pressure of the ozone gas into the water by increasing the water pressure as the ozone gas bubbles flow down the inner tube. Is promoted. As a result, the ozone absorption efficiency is improved by 5 to 10% as compared with the air diffusion method.

Further, the contact time between the ozone gas and the water to be treated can be increased by about 5 times or more, and the residence time in the contact tank can be reduced to 1/5 or less.

Further, the water depth of the deep U tube system is 20 to
Since the depth of the ozone treatment facility is about 4 to 5 times that of the normal aeration system, the installation area of the ozone treatment facility is about 1 times that of the aeration system.
/ 5.

[0015]

When the ozone treatment equipment is operated, a treatment target is set, and the amount of ozone supplied to the contact tank is controlled to supply an ozone amount corresponding to the quality and amount of the water to be treated.

As a method of controlling the amount of injected ozone, there are an ozone injection rate constant control, a discharged ozone concentration constant control, a dissolved ozone concentration constant control, water quality (UV value) control by ultraviolet absorbance, and the like.

However, in the case of controlling the water quality of the ozone contact tank, various indices such as the dissolved ozone concentration and the UV value are considered in principle, but the existing sensors are often unstable. Desired water quality control was difficult.

Therefore, the present invention takes advantage of the deep U-tube system and controls the amount of injected ozone without using a low-reliability sensor, and controls the concentration of exhausted ozone using a highly reliable gas phase ozone concentration meter. The purpose is to obtain stable water quality.

[0019]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention seeks to obtain the stable water quality without using a low-reliability sensor by utilizing the advantages of the deep U-tube system.

In the present invention, the first means for solving the above-mentioned problem is to perform constant control of the ozone injection amount (rate) without using a feedback signal at a constant pressure, and to uselessly inject ozone. To stabilize the water quality without performing.

That is, the pipe comprises a double pipe of an inner pipe and an outer pipe, and water to be treated and ozone gas flow in from the upper part of the inner pipe and flow down from the lower outlet of the inner pipe to the lower part of the outer pipe. An ozone contact tank that rises inside the outer tube to discharge treated water and unreacted waste ozone gas from the upper portion of the outer tube, and a water pipe that feeds water to be treated and ozone gas to the inner tube, A pressurized vortex pump for feeding the water to be treated and ozone gas into the ozone contact tank; a control means for controlling the pressure control valve provided on the pressurized vortex pump or the water supply pipe to control the water supply pressure or flow rate; An ozone generator, which controls the amount of ozone generated by control, and an injection ozone concentration meter that detects the concentration of injected ozone, injects the ozone gas generated by the ozone generator into the water pipe, and controls the amount of ozone gas injected. Pressurizing type A method for controlling a square injection ozone contact tank, the control of the ozone gas injection amount is sent under pressure constant control, setting in advance ozone injection rate (quantity) set value D _SET, treated water flow Q and the ozone gas flow rate detecting a Q _G, determine the injection ozone concentration target value P _in the following equation, obtains a power value by _{P in = D SET × (Q} / Q G) injecting ozone concentration detected with the calculated infusion ozone concentration target value The ozone generator is controlled by the electric power value so that the ozone injection amount is controlled to be constant.

Next, the second means is that it is difficult to say that a dissolved ozone concentration meter or a UV meter is highly reliable at present. It stabilizes water quality by controlling the concentration constant.

That is, the ozone injection amount is controlled by setting a waste ozone concentration set value in advance under a constant control of the water supply pressure of the water to be treated and the ratio of the water to be treated / ozone gas flow rate. An injection ozone concentration target value is obtained from the detected exhaust ozone concentration, an electric power value is obtained from the injection ozone concentration target value and the detected injection ozone concentration, and the ozone generator is controlled with the electric power value to control the exhaust ozone concentration at a constant level. It is characterized by doing.

Further, the third means is that the exhaust ozone concentration depends on the pressure, and the higher the pressure, the lower the exhaust ozone concentration. It performs constant control.

That is, the ozone injection amount is controlled by setting a target value of the injected ozone concentration and performing a constant control, and by controlling the ratio of the flow rate of the water to be treated / the flow rate of the ozone gas and the flow rate of the water to be treated to a constant value, to determine the ozone concentration beforehand. A set value is set, a target value of the exhaust ozone concentration is obtained from the set value of the exhaust ozone concentration and the detected exhaust gas concentration, and a target value of the pressure valve opening is obtained from the target value of the exhaust ozone concentration and the detected pressure value of the water to be treated. The exhaust ozone concentration is controlled to be constant by controlling the opening of the pressure valve with the target value of the opening of the pressure valve.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an explanatory view of a first embodiment of the present invention. In the first embodiment, the pressure is constant and the ozone injection amount (rate) is controlled constant without using a feedback signal. An object of the present invention is to stabilize water quality without performing unnecessary injection of ozone.

FIG. 1 is an explanatory diagram of a pressure fixing type ozone injection rate control method using a pressurized type downward injection ozone contact tank.

In FIG. 1, reference numeral 1 denotes a vertically long ozone contact tank, which has a double pipe structure of an outer pipe 2 and an inner pipe 3.
The lower end is an outlet, and the upper end penetrates the lid of the treated water tank 4 provided on the upper part of the outer pipe 2 and is fixed to the lid.

The treated water tank 4 is provided with a treated water delivery pipe 5 for delivering ozone treated treated water. Reference numeral 6 denotes a dissolved ozone concentration meter for measuring the concentration of dissolved ozone in the treated water.

Reference numeral 7 denotes a feed pipe for feeding the water to be treated and the ozone gas into the inner pipe 3. A pressurized vortex pump 9 and a pressure control valve 10 are provided on the way. The valve 10 is controlled by the control means of the inverter 8 and the valve opening adjusting section 10 'so that the water supply pressure and the flow rate are adjusted.

Reference numeral 11 denotes an ozone gas introduction pipe, which is provided on the inlet side of the pressurized vortex pump 9 and injects the ozone gas generated by the ozone generator 12 into the inlet pipe 7. Reference numeral 13 denotes an injected ozone concentration meter for measuring the concentration of the injected ozone.

Reference numeral 14 denotes an exhaust ozone discharge pipe, and the treated water tank 4
And discharges ozone gas that has not reacted with the water to be treated. Reference numeral 15 denotes this exhaust ozone concentration meter. Reference numeral 16 denotes a flow meter for measuring the flow rate of the water to be treated.

Reference numeral 17 denotes an ozone injection rate controller, and reference numeral 18 denotes an injection ozone concentration controller.

In the ozone treatment, the water to be treated and the ozone gas are fed into the inner tube 3 in the ozone contact tank 1 through the inlet pipe 7 by operating the pressurized vortex pump 9 and the flow at the lower end of the inner pipe is controlled. The space between the inner tube 3 and the outer tube 1 is raised from the outlet. During this time, the ozone gas continuously comes into contact with the water to be treated, dissolves and oxidizes harmful substances in the water to be treated. After the treated water once overflows into the treated water tank 4, the treated water delivery pipe 5
Sent from.

On the other hand, the ozone gas which has not reacted with the water to be treated is discharged from the ozone gas discharge pipe 14 via the treated water tank 4 as exhausted ozone gas, and is treated by a treatment device (not shown).

The control of the ozone injection rate (quantity), first, a flow rate Q from the flow meter 16 of the water to be treated in an ozone injection rate controller 17, enter the ozone gas flow rate Q _G of the ozone gas flow meter 19, the following equation to calculate the injected ozone concentration target value P _in.

P _in = D _SFT × (Q / Q _G ) where D _SFT is an ozone injection rate set value.

The injection ozone concentration target value P calculated here
_in is input to the injection ozone concentration controller 18.

Next, in the injected ozone concentration controller 18, the power value is calculated based on the input injected ozone concentration target value and the injected ozone concentration detected by the injected ozone concentration meter 13.
Calculated by D (proportional / integral / differential operation), input to the ozone generator 12 and adjust the power adjusting means in the ozone generator 12 to control the amount of ozone gas generated and the ozone injection amount (rate)
Is constantly controlled.

If there is a fluctuation in the flow rate of the water to be treated, the inverter 8 and the pressure control valve 10 are adjusted to keep the pressure constant and to minimize fluctuations in water quality. That is, in the pressurized downward injection type ozone contact tank, the removal rate of E260 (ultraviolet absorbance at a wavelength of 260 nm, usually used as an index of organic matter) is determined by the ratio (L / G) of the flow rate L of the water to be treated and the flow rate G of ozone gas. This is because the water quality is stable if the pressure is kept constant without depending on the pressure. By doing so, it is possible to realize ozone injection amount control in which stable water quality can be obtained without a feedback signal.

FIG. 2 is an explanatory view of a second embodiment of the present invention. In the second embodiment, a dissolved ozone concentration meter, a UV
At present, it is difficult to say that the meter or the like has high reliability. Therefore, the ozone injection amount control is realized by controlling the concentration of exhausted ozone using a highly reliable gas phase ozone concentration meter.

First, when the relationship between the ozone injection rate and the exhausted ozone concentration was verified, it was found that the relationship was as shown in FIG. FIG. 3 shows the ozone injection amount (g / Nm ³ ) on the horizontal axis,
The vertical axis represents the exhaust ozone concentration (g / Nm ³ ), and the pressure P =
It is a characteristic curve diagram showing the relationship between the concentration of exhausted ozone and the amount of injected ozone at 3.3 gf / cm ² and L / G = 15.5.

It can be seen from FIG. 3 that if the pressure and L / G are constant, the exhausted ozone concentration is a function of the ozone injection amount. Therefore, in the second embodiment of the present invention,
Using this relationship, the ozone injection amount is controlled using the exhausted ozone concentration signal as a feedback signal.

In FIG. 2, the same or corresponding parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

Reference numeral 20 denotes an exhaust ozone concentration controller, which receives the exhaust ozone concentration signal detected by the exhaust ozone concentration meter 15 and compares it with a preset exhaust ozone concentration set value to calculate a target value by PID. The calculated target value is input to the injection ozone concentration controller 18.

The injected ozone concentration controller 18 controls the input ozone concentration target value and the input ozone concentration
The power value is calculated based on the detection signal detected in step 3, and the amount of ozone gas generated by the ozone generator 12 is controlled. For example,
In the example of FIG. 3, when the exhausted ozone concentration is set to 1.0 g / Nm ³ , control is performed so that the ozone injection amount becomes 15 g / Nm ³ .

By performing such control, it becomes possible to control the amount of injected ozone using a highly reliable exhaust ozone concentration meter.

FIG. 4 is an explanatory view of a third embodiment of the present invention. This third embodiment has a feature of the pressurized downward injection method, that is, the concentration of exhausted ozone depends on the pressure. By using the characteristic that the exhaust ozone concentration decreases as the pressure increases, the exhaust ozone concentration is controlled by controlling the pressure.

First, the relationship between the exhaust ozone concentration and the pressure is verified as shown in FIG. FIG. 5 shows the pressure (Kgf /
cm ²⁾ it takes, the vertical axis represents the discharge ozone concentration (g / Nm ^3), injecting ozone concentration target value P _in the 21.5 ± 0.5 g /
FIG. 9 is a characteristic curve diagram showing a relationship between exhaust ozone concentration and pressure at Nm ³ and L / G = 14.5 ± 0.5.

FIG. 5 shows that the exhausted ozone concentration depends on the pressure, and the exhausted ozone concentration decreases as the pressure increases. In the third embodiment, the exhaust ozone concentration is controlled to be constant by changing the pressurization value by using this relationship.

In FIG. 4, the same or corresponding parts in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.

Reference numeral 21 denotes a pressure control valve opening controller, and reference numeral 22 denotes a flow control controller. First, the exhaust ozone concentration controller 20 calculates a target value of the exhaust ozone concentration by PID based on the exhaust ozone concentration and the set value of the exhaust ozone concentration. Next, the pressure control valve opening controller 21 calculates the pressure valve opening based on the exhaust ozone concentration target value calculated by the exhaust ozone concentration controller 20 and the pressure value detected by the pressure gauge 23. At this time, since the pressure value fluctuates, the flow rate controller 22 calculates a target rotation speed of the inverter 8 based on the flow rate detected by the flow meter 16 and the water flow set value. For example, in the example of FIG.
When Nm ³ is set, the pressure is controlled to be 1.8 kgf / cm ² .

By controlling in this way, the amount of ozone injected can be controlled by controlling the concentration of exhausted ozone without changing the amount of injected ozone.

[0055]

As described above, according to the present invention, a desired amount of ozone can be injected by controlling the amount of injected ozone without using a sensor and by controlling the concentration of exhausted ozone using a highly reliable gas-phase ozone concentration meter. The following effects can be obtained.

In the first embodiment, since the pressure can be kept constant even when the flow rate fluctuates, the ozone injection amount can be controlled so that the water quality is stable and stable water quality can be obtained without a feedback signal. Become.

In the second embodiment, the dissolved ozone concentration can be controlled by using a highly reliable exhaust ozone concentration meter.

In the third embodiment, constant control of the water quality (E260) can be performed by using a highly reliable exhaust ozone concentration meter.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

FIG. 3 is a characteristic diagram of a relationship between an exhausted ozone concentration and an ozone injection amount.

FIG. 4 is an explanatory diagram of a third embodiment of the present invention.

FIG. 5 is a characteristic diagram of the relationship between the concentration of exhaust ozone and the pressure.

FIG. 6 is a schematic diagram of a vertical detour type ozone contact tank.

FIG. 7 is a schematic view of a deep U tube type ozone contact tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ozone contact tank 2 ... Outer pipe 3 ... Inner pipe 4 ... Treatment water tank 5 ... Treatment water delivery pipe 6 ... Dissolved ozone concentration meter 7 ... Supply pipe 8 ... Inverter 9 ... Pressurized vortex pump 10 ... Pressure control valve 11 ... Ozone gas inlet tube 12 ... Ozone generator 13 ... Injection ozone concentration meter 14 ... Exhaust ozone discharge tube 15 ... Exhaust ozone concentration meter 16 ... Flow meter 17 ... Ozone injection rate controller 18 ... Injection ozone controller 19 ... Ozone gas flow meter 20 ... Exhaust Ozone concentration controller 21 ... Pressure control valve opening controller 22 ... Flow control controller 23 ... Pressure gauge 60 ... Ozone contact tank 61,62 ... Partition 63a, 63b, 63c ... Reaction chamber 64a, 64b, 64c ... Aeration tube 70 ... Ozone contact Tank 71: outer tube 72: inner tube 73: ozone generator 75: treated water tank

Claims (3)

[Claims] 1. An inner pipe and an outer pipe are formed as a double pipe, and water to be treated and ozone gas flow in from the upper part of the inner pipe and flow down from the lower outlet of the inner pipe to the lower part of the outer pipe. An ozone contact tank that rises inside the outer tube and flows out from the upper portion of the outer tube, and a water pipe that feeds water to be treated and ozone gas to the inner tube, and supplies the water to be treated and ozone gas to the ozone contact tank. A pressurized vortex pump for feeding, control means for controlling the pressure control valve provided on the pressurized vortex pump or the water supply pipe to control water supply pressure or flow rate, and ozone generation in which the amount of ozone generated is controlled by controlling the amount of electric power. A method for controlling a pressurized downward injection ozone contact tank comprising an apparatus, an injection ozone concentration meter for detecting the injection ozone concentration, injecting the ozone gas generated by the ozone generator into the water pipe, and controlling the injection amount of the ozone gas. , Previous Control of the ozone gas injection amount is below the feed pressure constant control, setting in advance ozone injection rate (quantity) set value D _SET, and detects the flow rate Q and the ozone gas flow rate Q _G of the water to be treated, injecting ozone by the following formula obtains a power value by _{P in = D SET × (Q} / Q G) injecting ozone concentration detected with the calculated infusion ozone concentration target value to obtain concentration target value P _in, and controls the ozone generator by said power value A method for controlling a pressurized downward injection ozone contact tank, wherein the ozone injection amount is controlled to be constant. 2. An inner pipe and an outer pipe are double pipes, and water to be treated and ozone gas flow in from the upper part of the inner pipe and flow downward from the lower outlet of the inner pipe to the lower part of the outer pipe. An ozone contact tank configured to rise inside the outer tube to flow and discharge treated water and unreacted waste ozone gas from the upper portion of the outer tube; and a water pipe for supplying the water to be treated and ozone gas to the inner tube, A pressurized vortex pump for feeding treated water and ozone gas into an ozone contact tank; control means for controlling the pressure control valve provided on the pressurized vortex pump or the water supply pipe to control water supply pressure or flow rate; And an injection ozone concentration meter for detecting the injected ozone concentration. The ozone gas generated by the ozone generator is injected into the water pipe, and the injection amount of the ozone gas is controlled. Press down injection In the method for controlling an ozone contact tank, the ozone injection amount is controlled by setting a waste ozone concentration set value in advance under a constant control of a water supply pressure of a water to be treated and a ratio of a water to be treated / ozone gas flow rate. The injection ozone concentration target value is obtained from the concentration set value and the detected exhaust ozone concentration, the power value is obtained from the injection ozone concentration target value and the detected injection ozone concentration, and the ozone generation device is controlled by the power value to control the ozone generation device. A method of controlling a pressurized downward injection ozone contact tank, wherein the concentration is controlled to be constant. 3. An inner pipe and an outer pipe are formed as a double pipe, and water to be treated and ozone gas flow in from the upper part of the inner pipe and flow down from the lower outlet of the inner pipe to the lower part of the outer pipe. An ozone contact tank configured to rise inside the outer tube to flow and discharge treated water and unreacted waste ozone gas from the upper portion of the outer tube; and a water pipe for supplying the water to be treated and ozone gas to the inner tube, A pressurized vortex pump for feeding treated water and ozone gas into an ozone contact tank; control means for controlling the pressure control valve provided on the pressurized vortex pump or the water supply pipe to control water supply pressure or flow rate; And an injection ozone concentration meter for detecting the concentration of injected ozone. The ozone gas generated by the ozone generator is injected into the water pipe, and the injection amount of the ozone gas is controlled. Press down injection In the method for controlling an ozone contact tank, the control of the ozone injection amount is performed by setting an injection ozone concentration target value and performing constant control, and controlling the ratio of the flow rate of the water to be treated / the flow rate of the ozone gas and the flow rate of the water to be treated to be constant. An exhaust ozone concentration set value is set in advance, a target value of the exhaust ozone concentration is obtained from the set value of the exhaust ozone concentration and the detected exhaust ozone gas concentration, and the pressure valve is opened based on the target value of the exhaust ozone concentration and the detected pressure value of the water to be treated. A method for controlling a pressurized down-injection ozone contact tank, wherein an exhaust ozone concentration is controlled to be constant by obtaining a target value of the pressure and controlling the opening of the pressure valve with the target value of the pressure valve opening.