JP7497643B2 - Water quality measuring device and water quality measuring method - Google Patents

Description

The present invention relates to a water quality measuring device and a water quality measuring method using water quality sensors such as a pH meter and a conductivity meter.

In controlling coagulation, it is important to control the pH in the coagulation reaction tank within a certain range, and this is generally achieved by adding alkaline and acidic chemicals. Ferric chloride (iron salt), an acidic chemical, is often used as an inorganic coagulant, and sodium hydroxide is often used to adjust the pH.

As measurements continue, suspended solids in the water, microorganisms, or iron hydroxide and iron oxide adhere to the surface of the pH electrode, gradually reducing the measurement accuracy and responsiveness. For this reason, the electrode is periodically removed and a cleaning operation is performed to remove contaminants that have adhered to the electrode surface using chemicals. Specifically, for example, the electrode is removed from the coagulation reaction tank and immersed in chemicals for a certain period of time, after which the electrode is washed with clean water and then reinstalled in the coagulation reaction tank.

Japanese Patent Application Laid-Open No. 7-222998

The present invention aims to provide a water quality measurement device and a water quality measurement method that can be cleaned without removing the water quality sensor.

The water quality measuring device of the present invention is a water quality measuring device equipped with a water quality sensor having a sensor body that contacts the water to be measured, and is equipped with a cover that surrounds the sensor body and forms a space between the sensor body and an opening provided in the cover to connect the space to the outside of the cover, fresh water supply means for supplying fresh water to the space, air supply means for supplying air to the space, chemical solution supply means for supplying a cleaning chemical solution to the space, and air communication means for connecting the inside of the space to the atmosphere.

In one aspect of the water quality measuring device of the present invention, the sensor body is rod-shaped and has a detection unit at its tip end, the cover is cylindrical, the opening is provided at the tip end of the cover located at the tip end of the sensor body, a base end nozzle for supplying air or liquid is provided at the base end of the cover, and a tip end nozzle for supplying air is provided at the tip end of the cover.

In one embodiment of the water quality measuring device of the present invention, a tube is connected to the opening.

The water quality measurement method of the present invention is a water quality measurement method using the water quality measurement device of the present invention, and includes a step of supplying a chemical solution to the space by the chemical solution supply means and cleaning the sensor body with the chemical solution.

In one aspect of the water quality measurement method of the present invention, measurements are taken intermittently using the sensor body, and the space is filled with fresh water between measurement steps.

In one aspect of the water quality measurement method of the present invention, air and clean water are supplied into the space for each measurement, and the sensor body is bubble-cleaned by a gas-liquid multiphase flow.

In one aspect of the present invention, when measuring water quality, air is first supplied to the space. This causes fresh water to be discharged from the space. Thereafter, the supply of air is stopped and the space is opened to the atmosphere. Then, the water to be measured flows into the space through the opening in the cover. The quality of the water in this space is measured, thereby measuring the quality of the water to be measured. After the measurement is completed, air and fresh water are supplied to clean the sensor body with a gas-liquid multiphase flow. If the output characteristics of the sensor body deteriorate, a chemical solution is introduced into the space for chemical cleaning.

In one aspect of the present invention, the space between the sensor body and the cover is filled with clean water when not measuring, preventing sludge from accumulating in the space and preventing slime from adhering to the sensor body.

1 is a configuration diagram of a water quality measuring device according to an embodiment.

The following describes the embodiment with reference to Figure 1.

As shown in Figure 1, the sensor 1, which is a pH meter or electrical conductivity meter, has a rod-shaped sensor body (probe in this embodiment) 1a that comes into contact with the water to be measured, a sensor base 1c to which the base end of the sensor body 1a is connected, and a cylindrical cover 1b that surrounds the sensor body 1a. There is a space S between the cover 1b and the sensor body 1a. The base end side of the cover 1b (the upper end side when in use) is watertightly fixed to the sensor base 1c, which has a larger diameter than the sensor body 1a.

An opening 2 is provided on the tip surface of the cover 1b so as to face the tip surface of the sensor body 1a. The opening diameter of the opening 2 is smaller than the inner diameter of the cover 1b. In the case of a pH meter or a conductivity meter, the diameter of the opening 2 is preferably 2 to 12 mm, and more preferably 3 to 6 mm.

A base end nozzle 10 for supplying air or liquid into the space S is provided on the base end side of the cover 1b. The rear end of the base end nozzle 10 protrudes outside the cover 1b, and a cleaning liquid supply pipe 12, a fresh water supply pipe 13, a compressed air supply pipe 14, and an atmosphere communication pipe 15 are connected to the rear end via pipes 11. Each of the pipes 11 to 15 may be a hard pipe such as a synthetic resin, or may be a soft tube. Solenoid valves 12a to 15a are provided midway along each of the pipes 12 to 15. A check valve may be provided in the pipe 12.

A tip nozzle 20 for blowing air into the cover 1b is installed on the side of the tip of the cover 1b. A compressed air supply pipe 21 is connected to the tip nozzle 20. A solenoid valve 21a is provided midway along the air supply pipe 21. Each solenoid valve 12a to 15a, 21a is controlled by an arithmetic controller (not shown). Manual valves may be provided instead of the solenoid valves.

The measurement signal of the sensor 1 is input to this calculation controller. The calculation controller includes a calculation output section that calculates and outputs measurement output data based on the measurement signal, and a solenoid valve control section that controls the opening and closing of solenoid valves 12a to 15a and 21a. The calculation controller includes a microprocessor and performs a series of operations described below according to a program.

The clean water may be tap water, distilled water, deionized water, pure water, ultrapure water, etc., but is not limited to these.

The cleaning liquid used has the property of removing any deposits from the sensor body 1a. If the deposits are mainly composed of iron hydroxide or iron oxide, an acid solution such as hydrochloric acid (e.g., 9% hydrochloric acid) is suitable as the cleaning liquid, but is not limited to this.

Preferred compressed air sources include a compressor, blower, air cylinder, etc. The end of the atmosphere communication pipe 15 is open to the atmosphere.

This sensor 1 is used by being installed so that the sensor body 1a is in contact with the water to be measured, such as in a tank or pipe, in the same way as a normal pH meter or conductivity meter.

[Measurement process]
To measure the water quality of the water to be measured (in this embodiment, water in a tank such as a coagulation reaction tank) using a water quality measuring device equipped with this sensor 1, the solenoid valve 14a is opened and the other solenoid valves are closed to introduce compressed air from the base end nozzle 10 into the space S, and the water in the space S is pushed out from the opening 2. In other words, when compressed air is supplied to the space S with the solenoid valve 14a opened and the other solenoid valves closed, the water in the space S flows out from the opening 2, and the space S becomes filled with air.

Then, solenoid valve 15a is opened and the other solenoid valves are closed to allow the water to be measured to flow into space S and perform the measurement process. That is, when solenoid valve 15a is opened and space S is connected to the atmosphere, the water to be measured flows into space S through opening 2 and is measured by sensor body 1a.

After the water in space S is pushed out by air in this way, space S is opened to the atmosphere, so that the water to be measured flows quickly into space S, quickly filling space S with the water to be measured, and measurement is then performed.

[Bubbling cleaning process]
After the measurement is completed, the solenoid valves 13a and 21a are opened and the other solenoid valves are closed. As a result, fresh water is continuously supplied from the base end nozzle 10 to the space S, and air is blown into the space S from the tip end nozzle 20, so that the tip end of the sensor body 1a is bubbling cleaned (gas-liquid multiphase flow cleaning). The cleaning wastewater flows out from the opening 2.

After performing this gas-liquid multiphase flow cleaning for a specified time, solenoid valve 13a is left open and solenoid valve 21a is closed, allowing only fresh water to flow through space S. As a result, space S is rinsed with fresh water, and air bubbles within space S flow out of opening 2 along with the flow of fresh water, leaving only fresh water in space S.

A set of bubbling cleaning, consisting of the above gas-liquid multiphase flow cleaning and the subsequent fresh water flow, may be repeated multiple times as necessary.

After one or more sets of bubbling cleaning are performed, the solenoid valve 13a is also closed, and the system waits until the next measurement step, or starts the next measurement step immediately. Note that providing a waiting step reduces the frequency or time that the sensor body 1a comes into contact with the water to be measured, thereby suppressing contamination of the sensor body 1a.

[Chemical cleaning]
The sensor body 1a is washed with a chemical solution periodically or when the phenomenon of insufficient dirt removal occurs.

This phenomenon of insufficient dirt removal can be detected from the change in output of the sensor body 1a during the fresh water flow process after the gas-liquid multiphase flow cleaning in the bubbling cleaning described above. For example, if the sensor body 1a is a pH meter, when the fresh water flow process begins, the output of the sensor body 1a will return to the pH of the fresh water (usually about 7), but if the time required for this return is longer than a specified time, or if the specified pH (for example, 6.5) is not reached even after a specified time has passed, it is determined that the phenomenon of insufficient dirt removal has occurred, and chemical cleaning is performed.

To perform chemical cleaning, the solenoid valve 12a is opened and the other solenoid valves are closed, the chemical solution is introduced into the space S to fill the space S with the chemical solution, and then the solenoid valve 12a is closed and this state (the immersion cleaning state of the sensor body 1a) is maintained for a predetermined time.
After the predetermined time has elapsed, the chemical solution (waste cleaning chemical solution) is discharged from the space S.

To discharge the chemical solution from space S, first, solenoid valve 14a is opened and the other solenoid valves are closed, and the chemical solution is discharged from space S through opening 2 by air pushing. Next, solenoid valve 15a is opened and the other solenoid valves are closed, allowing the water in the tank to flow into space S through opening 2, and then solenoid valve 13a is opened and the other solenoid valves are closed, allowing fresh water to flow into space S, pushing the water in space S out through opening 2 and filling space S with fresh water. Then solenoid valve 13a is also closed, and the process moves to the standby process, or, if it is time to measure, moves to the measurement process.

When pushing out the chemical solution after immersion cleaning in this way, air is pushed out first, then water in the tank is introduced, and then fresh water is circulated. This is to push out the chemical solution with air, expel the remaining air with the water in the tank, and then replace the water in the tank in the space S with fresh water. However, fresh water may be circulated immediately after the air is pushed out, or fresh water may be circulated immediately without pushing out the air.

In the above embodiment, the opening and closing of each solenoid valve is all performed by the arithmetic and control device, which significantly reduces the labor required for sensor maintenance. However, some or all of the operations may be performed manually. Even in this case, there is no need to remove the sensor 1 from the tank or piping, making maintenance work easy.

In the above embodiment, the opening 2 faces directly into the tank (or into the piping), but in the present invention, a tube may be connected to the opening 2.

If the opening 2 faces directly into the tank, there is a risk that the tank water may mix with the fresh water in the space S through the opening 2. For example, when rinsing the space S with fresh water, air may remain in the space S, and when the rinse is stopped, the air may shrink and the tank water may enter the space S. By connecting a tube to the opening 2, the tank water is prevented from entering the space S. Even if the tank water enters the space S, it is diluted with the fresh water in the space S, so there is little impact, but if the concentration of the tank water is high, there is a large advantage to connecting a tube. In the case of a pH meter or a conductivity meter, the internal volume of the tube is preferably about 50% of the size of S, the length of the tube is preferably about ×200 to 500 mm, especially about 300 to 400 mm, and the internal diameter is preferably about 4 to 12 mm, especially about 6 to 10 mm. It is preferable to set this depending on the water depth of the measurement tank to be inserted and the relationship with other tank equipment (mixing blades, etc.).

The water quality measuring device of the present invention can be suitably used in various wastewater treatment facilities such as coagulation reaction tanks and pure water production equipment, but can also be used for other purposes.

The above embodiment is an example of the present invention, and the present invention is not limited to the above embodiment. The present invention can also be applied to water quality measurements other than pH and electrical conductivity.

REFERENCE SIGNS LIST 1 sensor 1a sensor body 1b cover 2 opening 10 base end nozzle 20 tip end nozzle 12a to 15a, 21a solenoid valve

Claims (5)

In a water quality measuring device having a water quality sensor having a sensor body that comes into contact with the water to be measured,
a cover surrounding the sensor body and forming a space between the sensor body and the cover;
an opening provided in the cover so as to communicate the space with the outside of the cover;
A fresh water supply means for supplying fresh water to the space;
an air supply means for supplying air to the space;
A chemical supply means for supplying a cleaning chemical to the space;
and an atmosphere communication means for communicating the space with the atmosphere,
The sensor body is rod-shaped and has a detection unit at its tip end.
The cover is cylindrical,
The opening is provided on a tip side of a cover located on a tip side of the sensor body,
A base end nozzle for supplying air or liquid is provided on the base end side of the cover,
A nozzle for supplying air is provided at the tip of the cover.
the sensor is a pH meter;
A water quality measuring device characterized by having an arithmetic controller that, after introducing clean water into the space, operates a chemical supply means to perform chemical cleaning if the time it takes for the pH to return to the specified level exceeds a predetermined time. The water quality measuring device according to claim 1 , wherein a tube is connected to the opening. 3. A water quality measuring method using the water quality measuring device according to claim 1 , further comprising the step of: supplying a chemical solution to said space by said chemical solution supplying means, and cleaning said sensor body with the chemical solution. 4. The water quality measuring method according to claim 3 , wherein the measurement by the sensor body is performed intermittently, and the space is filled with fresh water between measurement steps. 5. The water quality measuring method according to claim 3 , wherein air and clean water are supplied into the space for each measurement, and the sensor body is bubbling-cleaned by a gas-liquid multiphase flow.

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