JPS6134618B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning device for a dissolved oxygen meter that automatically detects an indication error caused by dirt on a diaphragm, etc., and performs a cleaning operation adapted to the amount of error.

The activated sludge treatment method used for sewage treatment involves mixing sewage to be treated with a solution containing a group of microorganisms called activated sludge, and allowing these microorganisms to digest and decompose organic pollutants in the sewage. Therefore, the oxygen necessary for microbial activity must be supplied from outside. The most common method is aeration, which involves forcibly mixing air bubbles into the water using an air pump such as a blower. This aeration causes oxygen in the air to dissolve in the water and become dissolved oxygen, which is ingested by microorganisms and used to aid their activities. In this case, the dissolved oxygen concentration must be controlled to an appropriate value, and a dissolved oxygen meter is used to measure it.

There are several measurement principles for dissolved oxygen meters, but the diaphragm electrode method is generally used. In this diaphragm electrode method, dissolved oxygen in the sample water passes through a synthetic resin diaphragm and enters the instrument, where it is converted into a current value by an anode and a cathode within the instrument, providing an indication corresponding to the concentration.

However, since the detector is immersed in sample water containing polluted sewage, the surface of the diaphragm inevitably becomes dirty, and this dirt causes deterioration of the dissolved oxygen meter's reading. When deterioration occurs, it generally results in a reduced reading, which not only does not indicate the correct dissolved oxygen concentration, but also slows down the response. Cleaning is often done to prevent this stain. Cleaning methods include mechanical cleaning (ultrasonic cleaning, water jet cleaning) and chemical cleaning (cleaning agents), and water jet cleaning is used for dissolved oxygen meters.

This cleaning method uses cleaning water (usually tap water) to
This is a method in which the liquid is sprayed toward the diaphragm of the electrode for a certain period of time at a certain period. This method mechanically removes dirt adhering to the diaphragm surface of the dissolved oxygen meter.

However, even when water jet cleaning is performed, a complete cleaning effect cannot be obtained, and long-term accumulation of dirt is unavoidable. Therefore, it is necessary to know how much error there is under normal usage conditions due to the accumulation of dirt. However, to do this, it is necessary to take out the detection part, immerse it in a standard solution, and compare the value of the standard solution with the value actually indicated by the meter.

Based on the above comparison results, the intensity of water jet cleaning is changed depending on the degree of dirt accumulation, but the water quality changes hourly, so the washing intensity can be adjusted manually according to the changing water quality and dirt level. It is virtually impossible to change it. Furthermore, even if you try to perform this operation automatically, the degree of contamination is mainly determined through manual operation by staff as described above, and errors due to contamination cannot be detected automatically, so it is not possible to perform the above automatic operation. I can't.

Currently, staff members check the cleaning equipment every week or month to understand the degree of contamination and error in instructions, and change the cleaning intensity based on the results. In this case, between checks, both the indicated value and the water jet cleaning are in a state that deviates from the optimum state, which poses a serious problem regarding the reliability of dissolved oxygen concentration measurement.

Furthermore, since the cleaning itself is performed at a constant intensity regardless of changes in water quality, it cannot respond to sudden changes in water quality, and stains due to sudden deterioration of water quality are accelerated, resulting in unsatisfactory effects. As a result, even if cleaning is performed, a reduction in maintenance frequency cannot be expected.

The purpose of the present invention is to automatically detect indication errors due to cleaning dirt etc. during measurement, and automatically perform cleaning appropriate to the amount of error, thereby making it possible to properly clean dirt with dissolved oxygen. The purpose is to obtain a cleaning device for the meter.

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

First, there are two ways to install a dissolved oxygen meter:
There are seeds. One method is to install it inside a bath or open tank, and this is called an immersion-type dissolved oxygen meter. Others are installed midway through the pipeline and are called flow-through dissolved oxygen meters. This invention is implemented as an immersion type dissolved oxygen meter.

FIG. 1 shows a state in which a detector 1 of a dissolved oxygen meter is installed underwater. A cleaning device 2 is provided at the tip of the detector 1, and a nozzle 4 for spraying cleaning water 3 toward the cleaning device 2 is provided near the cleaning device 2. Dissolved oxygen in the sample water 5 enters the detector 1 through the cleaning 2 located at the tip and is obtained as an instrument indication. In addition, in order to deal with stains caused by the sample water 5, cleaning water 3 is periodically jetted from a nozzle 4 located below the detector 1 to remove stains on the cleaning surface 2.

The overall configuration of the cleaning device will be explained below with reference to FIG.

In FIG. 2, reference numeral 7 denotes a cleaning water tank, in which cleaning water 3 for the diaphragm of the detector 1 is stored. This wash water 3 is aerated by an aeration device consisting of an air pump 12a and an aeration pipe 12b so that the dissolved oxygen concentration is always saturated. Reference numeral 23 denotes a cleaning water supply device, which is equipped with a pump 8, a control valve 9, a solenoid valve 10, and a pressure gauge 11 in a pipe line leading from the cleaning water tank 7 to the nozzle 4, and is configured to supply the cleaning water 3 to the nozzle 4 at a predetermined pressure. Supplied at The above-mentioned predetermined pressure is a value at which a discharge pressure capable of covering the surface of the diaphragm of the detector 1 with the cleaning water 3 jetted from the nozzle 4 is obtained.

14 is a controller, which receives the measured value from the detector 1;
That is, the dissolved oxygen concentration in the sample water 5 is measured by the amplifier 13.
to execute various functions described below.
Reference numeral 24 denotes a changeover switch, which is in contact with the terminal a side during normal measurement, and is switched to the terminal b side during cleaning. Reference numeral 18 denotes a conversion means in which a saturation value of dissolved oxygen concentration with respect to water temperature is set in advance. That is, the saturation value of the dissolved oxygen concentration varies depending on the water temperature, but when the liquid does not contain a large amount of dissolved matter, the saturation value of the dissolved oxygen concentration can be uniquely determined by the water temperature. The conversion means 18 is the temperature sensor 6
The temperature of the cleaning water 3 is inputted by , and the saturation value of the dissolved oxygen concentration (the saturation value of the cleaning water 3) corresponding to this temperature can be outputted from a preset relationship. Comparison means 17 compares the measured output of the detector 1 and the output of the conversion means 18 (both dissolved oxygen concentrations) and outputs the deviation thereof. Reference numeral 15 denotes cleaning amount setting means, which increases or decreases the amount of cleaning for the diaphragm of the detector 1 in accordance with the deviation output from the comparison means 17. A specific method for increasing or decreasing the amount of cleaning is to change the cleaning time or cleaning cycle, for example, by giving on/off commands to the pump 8 and solenoid valve 10 of the cleaning water supply device 23, and changing the cleaning water supply. The supply timing (supply amount of cleaning water) by the device 23 is controlled. Note that the initial values of the cleaning time and cleaning cycle are set in advance according to the water quality of the sample water 5 to be measured.

16 is an indication holding means, during normal measurement,
The measured value input through the terminal a of the changeover switch 24 is output as is, but when the signal from the cleaning amount setting means 15 indicates that cleaning is in progress, the value before cleaning is held and the value is changed. Output. By doing so, during cleaning, disturbances are not caused to various control devices that use the measured value of the dissolved oxygen meter as an input signal.

In the above configuration, by increasing the water pressure of the cleaning water 3 jetted from the nozzle 4 in accordance with the flow velocity near the detector 1, the cleaning water 3
You can cover it with At this time, detector 1
The indication should indicate the dissolved oxygen concentration of the wash water 3.

Figure 3 shows the dissolved oxygen meter reading when the dissolved oxygen concentration of the cleaning water 3 injected from the nozzle 4 is kept constant and the cleaning water is injected at such a pressure that the surface of the cleaning water 3 is covered by the cleaning water 3. show. The peak-like indication shown in the figure is the dissolved oxygen concentration of the wash water 3. Other instructions indicate the dissolved oxygen concentration of sample water 5.
As is clear from the figure, regardless of the change in the dissolved oxygen concentration of the sample water 5, when the cleaning water 3 is injected, the cleaning water 3
Shows only dissolved oxygen concentration. The saturated value of the dissolved oxygen concentration changes depending on the water temperature, but when the liquid does not contain a large amount of dissolved matter, the saturated dissolved oxygen concentration can be uniquely determined by the water temperature. Figure 3 shows
This is an example of an instruction when the temperature of the cleaning water 3 is kept constant.

The present invention utilizes the above-mentioned characteristics, and the cleaning water 3 in the cleaning tank 7 is aerated by the aeration device 12 so that the dissolved oxygen concentration always reaches the saturated value. Further, a temperature detector 6 is provided to detect the dissolved oxygen concentration in this saturated state, and its measured value is output to the converter 18. Further, the supply pressure by the cleaning water supply device 23 is set relatively high so that the cleaning surface of the detector 1 is covered with the cleaning water 3 jetted from the nozzle 4 . Of course, the injection intensity of the cleaning water 3 from the nozzle 4 cannot be set to any desired value, and the pressure gauge 11 and the control valve 9 must be adjusted to an appropriate value so as not to cause damage or deterioration of the cleaning water 2.
Set using . During normal measurement, the dissolved oxygen meter detector 1 is immersed in the sample water 5 and detects the dissolved oxygen concentration of the sample water 5.

The electrical signal from the detector 1 is amplified by the amplifier 13 to a practical level and input to the controller 14. The controller 14 is controlled by a cleaning amount setting means 15. During normal measurement, the measured value from the amplifier 13 is not held in the instruction hold section 16,
It is output to the outside as is. At the time of cleaning, the instruction holding unit 16 is sent from the cleaning amount setting means 15 in advance.
A cleaning signal is issued and the dissolved oxygen measurement is held.

At the start of cleaning, the cleaning water 3 stored in the cleaning water tank 7 is pumped by the cleaning pump 8, passes through the control valve 9 and the solenoid valve 10, and is injected from the nozzle 4 into the sample water 5, and the diaphragm of the detector 1 Wash 2. The indicated value obtained at this time is the controller 14
The comparing means 17 compares the original dissolved oxygen concentration (saturation value corresponding to temperature) of the cleaning water 3 obtained from the converting means 18. As a result of comparing these two types of dissolved oxygen concentrations, the comparison section 17 outputs a deviation. This deviation represents the amount of dirt on the diaphragm, and in order to obtain the cleaning time and cleaning cycle according to the size, the initial value regarding the cleaning amount (cleaning time, cleaning cycle) preset in the cleaning amount setting means 15 is changed. do. With this changed cleaning time and cleaning cycle,
By controlling the cleaning water supply device 23, cleaning can be automatically performed depending on the dirt on the diaphragm.

By using the above-mentioned device configuration, it is now possible to grasp the dirt on the detector 1 and the resulting error in readings, which previously had to be done manually, and to manually set the cleaning time and cleaning cycle based on the results. In the present invention, it is possible to grasp the instruction status moment by moment fully automatically, and based on the results, it is possible to automatically set the cleaning time and cleaning cycle according to the degree of progress of the stain. As a result, the reliability of dissolved oxygen measurement is increased, and appropriate cleaning is performed in response to dirt, so maintenance efforts for the dissolved oxygen meter can be reduced and its lifespan can be extended.

Another embodiment of the present invention will be explained in FIG.

In the above embodiment, only one type of cleaning water is used, but zero and span calibration of the dissolved oxygen meter can be performed by using two types of cleaning water with different concentrations.

FIG. 4 shows an application example of automatic zero and span calibration according to the present invention. Zero standard solution 1
9. Using the span standard solution 20 as cleaning water, it is possible to calibrate the dissolved oxygen meter to the regular indication using the data processing device 21 such as a computer based on the value obtained at this time.

As described above, according to the present invention, it is possible to automatically determine the dirty state of the dissolved oxygen diaphragm and perform appropriate cleaning according to the degree of dirt, so that the conventional manual cleaning is possible. The diaphragm can be cleaned properly and the diaphragm can be kept in good condition at all times. As a result, reliability in measuring dissolved oxygen concentration is improved.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the state in which the detector of the dissolved oxygen meter is immersed in sample water and the cleaning water from the nozzle is injected towards the detector diaphragm surface, and Fig. 2 is the dissolved oxygen according to the present invention. Fig. 3 is a diagram showing the difference in the indicated values of the dissolved oxygen meter between the state shown in Fig. 1 and the state during normal measurement; 1 is a configuration diagram of a dissolved oxygen meter that can perform automatic zero and span calibration. 1...Detector, 2...Diaphragm, 3...Washing water, 4...Nozzle, 5...Sample water, 6...Temperature detector, 12...Aeration device, 15...Cleaning amount setting means, 17...Comparing means, 1
8... Conversion means, 23... Washing water supply device.

Claims (1)

[Scope of Claims] 1. A cleaning device for a dissolved oxygen meter that sprays cleaning water from a nozzle toward a diaphragm of a detector of a dissolved oxygen meter immersed in sample water to clean the diaphragm, comprising: an aeration device that keeps the oxygen concentration in a saturated state at all times; a cleaning water supply device that supplies the cleaning water to the nozzle at a pressure that allows the cleaning water discharged from the nozzle to cover the surface of the diaphragm; and the cleaning a temperature measuring device for measuring the temperature of water; a converting means for outputting a saturation value corresponding to the predetermined value of the temperature measuring device, in which a saturation value of dissolved oxygen concentration is set in advance according to the water temperature; and a comparison means for comparing the output of the detector with the output of the detector to determine the deviation thereof; and a cleaning amount setting means for increasing or decreasing the amount of cleaning water supplied by the cleaning water supply device in accordance with the deviation. Dissolved oxygen meter cleaning device featuring: