JPH04225896A - Ozone injection controller - Google Patents

Abstract

PURPOSE:To appropriately control the injection of ozone to the amt. requisite for treated water by measuring the quality of treated water to correct the concn. of ozone to be injected, and thereby correcting the concn. of ozone gas injected for the treated water quality. CONSTITUTION:The flow rate of ozone to an ozone contact tank 11 is controlled by a controller 18 through a flowmeter 22 and a valve 15, and the injection of ozone from an ozonizer 12 is fixed through a flowmeter 21 in conformity to the flow rate. The injection of ozone is corrected in accordance with the treated water quality measured by a fluorophotometer 26. The concn. of ozone is also corrected for the treated water quality measured by the fluorophotometer 26, while the concn. of injected ozone gas measured by an ozone densitiometer 20 is fixed for the flow rate by the flowmeter 22.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone injection control device for ozone treatment of water to be treated.

0002

BACKGROUND OF THE INVENTION Ozone has the second highest oxidizing ability after fluorine, and is used in the water treatment field for sterilization, algaecide, decolorization, deodorization, and oxidative decomposition of organic and inorganic substances. For ozone treatment at water purification plants, pretreated ozone raw material gas (air, pure oxygen) is supplied to an ozone generator, and the ozone gas generated from the ozone generator is injected into the treated water in an ozone contact (reaction) tank. Exhaust ozone treatment is carried out in which the ozone that is not dissolved in the treated water and diffuses in the ozone contact tank is discharged without harming the human body and at an ozone concentration below the olfactory value.

FIG. 6 illustrates a conventional ozone treatment facility. The water to be treated is introduced into a gravity flow type ozone contact tank 1, and ozone gas is blown into the treated water in the ozone contact tank 1 from an ozone generator 2 through an aeration pipe 3, and ozone is dissolved in the treated water. Deodorization etc. are done in An intake pipe 4 is provided in the upper part of the ozone contact tank 1, and gas containing ozone, which is diffused or discharged from the treated water as bubbles, is taken in from the intake pipe 4 by a gas blower 5 and sent to an exhaust ozone treatment device (not shown). taken out. Ozone injection control to be supplied from the ozone generator 2 to the ozone contact tank 1 is controlled by a control device 6.

[0004] Here, there are the following three methods for controlling ozone injection.

(A) The ozone injection rate is set in the control device 6, and the flow rate of the treated water into the ozone contact tank 1 is measured by the flow meter 7.
Ozone injection rate control method that detects the amount of ozone and adjusts the amount of ozone injection proportional to the amount of water being treated.

(B) The dissolved ozone concentration of the treated water is set in the control device 6, the ozone concentration of the treated water taken out from the ozone contact tank 1 is detected by the concentration meter 8, and the ozone is adjusted to maintain the concentration set value. Ozone concentration control method that controls the injection amount.

(C) The concentration of exhausted ozone from the ozone contact tank 1 is set in the control device 6, the concentration of exhausted ozone discharged from the ozone contact tank 1 is detected by the concentration meter 9, and the ozone is adjusted to maintain the concentration set value. Exhaust ozone concentration control method that controls the injection amount.

[0008]

[Problems to be Solved by the Invention] Conventional ozone injection control systems all control the amount of ozone injection with respect to the amount of treated water, and do not take the quality of treated water into consideration. For this reason, a difference arises between the amount of ozone injected that the treated water requires and the actual amount of ozone injected. For example, if the actual amount of ozone injected is less than the amount required for treated water, the desired quality of the treated water will not be obtained, and conversely, if the amount of ozone injected is too large, ozone will be wasted. This also increases running costs.

An object of the present invention is to obtain appropriate ozone injection control required for treated water.

0010

[Means for Solving the Problems] In order to solve the above problems, the present invention provides an ozone treatment in which water to be treated is introduced into an ozone contact tank and ozone is blown into the water to be treated in the ozone contact tank. , processing flow rate constant control means for keeping the treatment flow rate constant in ozone treatment; ozone injection amount control means for making the amount of ozone gas injected into the ozone contact tank constant with respect to the treatment flow rate by the treatment flow rate constant control; The present invention is characterized by comprising an ozone injection concentration correction control means for correcting the ozone injection amount in accordance with water quality measurement values.

[0011]

[Operation] According to the present invention configured as described above, the ozone gas injection and concentration with respect to the treatment flow rate is made constant by the constant treatment flow rate control and the constant ozone gas injection rate control, and the ozone injection concentration correction control based on the water quality measurement of the treated water is performed to control the quality of the treated water. Correct the ozone gas injection concentration.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of an apparatus showing an embodiment of the present invention. In the figure, the ozone gas contact tank 11 is shown as having a single layer structure, but it has the same structure as the ozone contact tank 1 described above. The ozone gas (air or pure oxygen) that is force-fed by the compressor 13 causes the ozone gas generated by the ozone generator to be sent to the diffuser pipe 14 . The water to be treated is valve 1.
5 and introduced into the ozone gas contact tank 11. The treated water treated in the ozone contact tank 11 is supplied to the valve 16.
The flow rate is controlled and discharged. Ozone contact tank 11
The exhaust ozone is sucked in by the blower 17 and sent to an exhaust ozone treatment device (not shown) for exhaust.

The control device 18 has a computer 19 as its control center, and controls the amount of inflow of treated material into the ozone contact tank 11, the amount of outflow of treated water, and the amount of discharged ozone, as well as the amount of ozone injected. For this reason, the ozone generator 12
An ozone gas concentration meter 20 for detecting the ozone gas concentration and a flow meter 21 for detecting the ozone gas flow rate are provided in the ozone gas injection pipe line from the to the diffuser pipe 14. In addition, a flowmeter 22 for detecting the amount of inflow into the ozone contact tank 11 and a fluorescence spectrophotometer 23 for detecting the quality of the water to be treated from fluorescence spectrophotometry are installed on the piping path that introduces the water to be treated into the ozone contact tank 11. provided. The filtration device 24 removes blocks and the like when introducing the water to be treated into the fluorometer 23 by flow injection.

The treated water discharge pipe from the ozone contact tank 11 is provided with a flow meter 25 for detecting the amount of treated water flowing out, a fluorescence spectrophotometer 26 for detecting the quality of the treated water flowing out, and a filtration device 27. Further, a flow meter 28 for detecting the flow rate of the exhaust ozone gas and an ozone concentration meter 29 for detecting the ozone concentration of the exhaust ozone gas are provided in the exhaust ozone piping from the ozone contact tank 11. Further, the ozone contact tank 11 is provided with a water level gauge 30 for detecting the water level in the tank.

The water quality is measured using the fluorescence spectrophotometers 23 and 26 as an index of organic matter in the treated water. In other words, the fluorescence emission of an object is one of the relaxation phenomena of molecules that absorb light and transition to an excited state, indicating the dynamic behavior of molecules, and the fluorescence intensity is expressed as the product of the amount of absorbed light and the absorption rate of fluorescence amount, as shown in the figure. As shown in Figure 2, there is a high correlation between fluorescence intensity and ultraviolet absorbance (370 nm), and as shown in Figure 3, there is a high correlation with permanganate consumption (organic substance index). has a high correlation with chromaticity. Based on these correlations, a detection signal corresponding to the quality of the treated water is obtained by measuring the fluorescence intensity and chromaticity of the treated water.

The control device 18 controls the amount of ozone generated by controlling the ozone generator 12 based on the detection signals from each of the above-mentioned detectors, controls the amount of water flowing into the ozone contact tank 11 by controlling the valve 15, Ozone contact tank 1 controlled by valve 16
Control of the amount of treated water flowing out from 1 and control of the amount of ozone discharged by controlling the blower 17 are performed.

Among these, the control from the treated flow rate is performed using the treated water inflow/outflow amount signals of the ozone contact tank 11 from the flow meters 22 and 25 and the water level signal from the water level gauge 30 with respect to the set treatment target value. By controlling the flow rate of valves 15 and 16, the amount of processing per unit time is controlled while keeping the water level in the tank constant. In parallel, the amount of ozone gas injected and discharged into the ozone contact tank 11 is determined by multiplying the set ozone gas injection amount target value by the respective detection signals of the flow meters 21 and 28 and the ozone concentration meters 20 and 29. , the difference (the amount of ozone injection) is controlled as the amount of ozone injection for the unit amount of water to be treated. This control is performed electrically, either by the pressure of the compressor or by the amount of pure oxygen produced by the ozone generator.

Next, the control based on the quality of the treated water is performed by fluorescence spectroscopy with constant control of the inflow water amount Qin and outflow water amount Qout for constant treatment flow rate control based on the above-mentioned control based on the amount of treated water, and constant control of the ozone gas injection amount 90. Photometer 23, 26
The ozone injection amount from the ozone injector 12 is corrected and controlled according to the water quality detection signal. Through this correction control, the amount of ozone injection is adjusted according to the quality of the water to be treated. The ozone injection correction control will be explained in detail below.

The fluorescence spectrophotometer 26 continuously measures the fluorescence intensity I of the treated water by flow injection.
The control device 18 calculates the difference ΔI from the preset fluorescence intensity Iset, and calculates the ozone injection correction value ΔCo from this difference ΔI.
is calculated, and the currently set ozone injection amount setting value Co is feedback-corrected. These correction values ΔCo and set values C
o corresponds to the ozone injection concentration correction value and concentration setting because the control based on the amount of treated water is such that the inflow and outflow amounts are constant and the ozone contact tank water level is constant.

The ozone injection concentration correction control described above is performed as follows depending on whether the difference ΔI is zero, positive, or negative.

(1) When ΔI (=I-Iset)=0, the measured fluorescence intensity I is the same as the set value Iset,
Since it is in the optimal ozone injection control state, ozone injection concentration is not corrected and ozone injection concentration constant control is continued.

(2) When ΔI>0, in order to increase the ozone injection concentration, calculate the ozone injection correction concentration +ΔCo for the fluorescence intensity difference ΔIp as shown in FIG.
The ozone injection concentration is increased by adding ΔCo to the current ozone injection concentration Co.

(3) In the case of ΔI<0, in order to lower the ozone injection concentration, as shown in FIG. Reduce the ozone injection concentration by adding to the Co concentration.

In addition to the ozone concentration correction control described above, the fluorescence spectrophotometer 23 installed on the inflow side of the water to be treated measures the fluorescence intensity of the inflow water, and the control device 18 measures the difference from the preset fluorescence intensity. is determined, an ozone injection correction value is determined from this difference, and the currently set ozone injection amount setting value is feedforward corrected. This correction is performed in the same manner as the feedback correction described above, but by correcting the ozone injection amount in advance in response to changes in the quality of the water to be treated, it is possible to respond to sudden changes in water quality with less control delay. Additionally, by measuring the water quality on both the inflow and outflow sides of treated water, it is possible to monitor the effectiveness of ozone treatment.

[0025] In the examples, the fluorescence spectrophotometer 2
3 and 26 have a structure in which the water sampling points on the inflow side and the outflow side are periodically switched by switching valves using one fluorescence spectrophotometer, and the same effect can be obtained. Similarly, ozone measurement can be switched between the ozone concentration meters 20 and 29 using one ozone concentration meter.

[0026]

[Effects of the Invention] As described above, according to the present invention, a constant treatment flow rate control and a constant ozone gas injection amount control for the treatment flow rate are performed for ozone treatment, and in addition to this, the ozone injection amount is corrected by measuring the quality of treated water. As a result, the ozone treatment from the flow rate of the treated water has the effect of keeping the ozone injection amount appropriate even when the quality of the treated water changes.

[Brief explanation of the drawing]

FIG. 1: Device configuration diagram of an example.

[Figure 2] Correlation diagram between ultraviolet absorbance and fluorescence intensity of treated water,

[
Figure 3: Correlation diagram between permanganate consumption and fluorescence intensity in treated water,

[Figure 4] Correlation diagram between ultraviolet absorbance and chromaticity of treated water,

[Figure 5
] Relationship diagram between corrected ozone concentration and fluorescence intensity difference,

FIG. 6 is a diagram showing the configuration of a conventional device.

[Explanation of symbols]

11... Ozone contact tank, 12... Ozone generator, 15, 16
... Valve, 17... Blower, 18... Control device, 20, 29... Ozone concentration meter, 21, 22, 25, 28... Flow meter, 23,
26...Fluorescence spectrophotometer, 30...Water level meter.

Claims (4)

[Claims] 1. In ozone treatment in which water to be treated is introduced into an ozone contact tank and ozone is injected into the water to be treated in the ozone contact tank, a treatment flow rate constant control means for keeping the treatment flow rate constant for ozone treatment; , ozone injection amount control means that keeps the amount of ozone gas injected into the ozone contact tank constant with respect to the treatment flow rate by the treatment flow rate constant control, and ozone injection concentration correction control that corrects the ozone injection amount according to the measured water quality value of the treated water. An ozone injection control device characterized by comprising means. 2. The constant treatment flow rate control means is configured to control the inflow rate and outflow rate of the treated water based on the inflow rate and outflow rate of the treated water to the ozone contact tank and the level of the treated water in the ozone contact tank. Injection control device. 3. The ozone injection amount control means is configured to control the ozone injection amount obtained from the product of the ozone injection flow rate and its ozone concentration measurement value, and the ozone injection amount obtained from the product of the exhaust/flow rate from the ozone contact tank and its ozone concentration measurement value. An ozone injection control device configured to control the amount of ozone gas injected based on the emission amount. 4. The ozone injection concentration correction control means measures the fluorescence intensity of the inflow and outflow treated water of the ozone contact tank, calculates the ozone injection correction value from the difference between the fluorescence intensity and the set value, and determines the ozone injection correction value. An ozone injection control device configured to correct the amount of ozone gas injection using a correction value.