JP2005265608A - Stain removing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stain removing method which enables the effective removal of the stain bonded to a sensor immersed in water to be measured to always keep a high measuring precision. <P>SOLUTION: In washing off the stain of a concentration sensor for receiving at least one of a transmitted light transmitted through water to be measured of light applied into water to be measured from a floodlight part, scattered light scattered by a suspension contained in the water to be measured and reflected light reflected by the suspension, a gas-liquid mixed stream, wherein washing water and air are mixed, is introduced into the space between the floodlight part and a light detecting part to remove the stain bonded to the concentration sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a soil removal method for each sensor installed in a suspension, and more particularly to a soil removal method suitable for cleaning a concentration sensor used in an optical suspension concentration meter.

  Conventionally, various sensors installed in a suspension are likely to be contaminated and an error occurs in a measured value, so that it is necessary to remove the dirt. Examples of sensors that measure physical properties of water to be measured include a thermometer, a pressure gauge, a viscometer, a flow meter, a flow meter, a pH meter, and an ORP (oxidation reduction potential) meter. Moreover, as a sensor which measures the amount of impurities in water to be measured, for example, a suspension concentration meter, a conductivity meter, various ion meters, a DO (dissolved oxygen) meter, an ultraviolet absorbance meter, a TOC meter, a COD meter, a BOD meter, There are sensors used for TOD meters and the like.

The background art will be described below by taking a concentration sensor used for a suspension concentration meter as an example of the sensor.
As a concentration sensor used in a suspension concentration meter, one that measures the concentration of a suspension contained in water to be measured using a particle state detection probe is known (see, for example, Patent Document 1). . As shown in FIG. 5, this type of concentration sensor receives a light projecting unit 1 that irradiates laser light to the water to be measured M, and transmitted light that is provided in the vicinity of the light projecting unit and passes through the water to be measured. At least one of a transmitted light receiving unit 2 _T , a scattered light receiving unit 2 S that receives light scattered or reflected by the suspended matter contained in the water to be measured and a reflected light receiving unit 2 _R is provided. 2 (2 _T , 2 _S , 2 _R ) is applied to an optical suspension concentration meter equipped with a concentration measuring unit 3 for measuring the concentration of the suspension contained in the water to be measured from the level of light received. The

By the way, in the above-described concentration sensor, floating substances and sludge often adhere to the surfaces of the light projecting unit 1 and the light receiving unit 2, and it cannot be denied that the detection accuracy of the sensor decreases when these adhere. . Therefore, it is necessary to clean the light projecting surface of the light projecting unit 1 and the light receiving surface of the light receiving unit 2 constantly or periodically. Ultrasonic sensor cleaning method that measures the interface level between supernatant water and sludge in a sedimentation tank in a sedimentation tank provided for wastewater treatment or sewerage as a similar technique for cleaning this type of sensor using an ultrasonic sensor Is known (see, for example, Patent Documents 2, 3, and 4)
Japanese Patent Application No. 2002-337778 JP-A-9-318420 JP 2003-302279 A Japanese Patent Application No. 2004-028256

  However, the above-described dirt removal method is a method in which a liquid such as water is ejected from the nozzle toward the transmission / reception surface of the sensor, and there is a problem that good cleaning cannot be obtained. In other words, the method of jetting liquid in liquid replaces the liquid in the vicinity of the sensor and pushes out coexisting solids, etc., but the jetting speed of the liquid for cleaning is reduced in the supernatant water. For this reason, it is difficult to remove the dirt adhering to the sensor. Further, when the liquid ejection speed is increased, the effect of removing dirt increases, but there is also a problem that the spray diffusion region becomes narrow and effective cleaning cannot be performed.

  For this reason, in order to employ a method of injecting a high-pressure liquid onto the transmission / reception surface of the sensor, a large number of injection pipes are provided so that the jet flows on the entire surface of the sensor, and the mutual jets do not interfere with each other. It has been necessary to adopt a complicated mechanism such as providing a mechanism that injects in order or a variable nozzle mechanism that can change the angle of the nozzle to an arbitrary angle. As described above, there is a problem that it is difficult to obtain a sufficient cleaning effect with a simple mechanism in the method of ejecting the liquid onto the transmission / reception surface of the sensor.

  Further, in the above-described prior art, there is a method of cleaning the sensor by using a gas-liquid mixed state formed when gas is injected into the water to be measured. In the case where the water to be measured contains a lot of impurities, especially if it contains a lot of suspended solids, the liquid near the sensor is replaced and coexisting solid matter Although there is an effect of extruding the sensor etc., there is a problem that the effect of peeling off the dirt adhering to the sensor is lowered, and therefore, the sensor cannot be satisfactorily cleaned.

  The present invention has been made in response to such a conventional situation, and an object of the present invention is to provide a sensor immersed in measurement water, particularly a light projecting unit and a light receiving unit of an optical turbidity concentration meter. An object of the present invention is to provide a dirt removing method capable of effectively removing attached dirt and always maintaining high measurement accuracy.

In order to achieve the above-described object, a dirt removing method according to the present invention is installed in measured water made of a suspension as described in claim 1, and measures a physical property and an impurity amount of the measured water. When removing the dirt, a gas-liquid mixed flow in which cleaning water and gas are mixed is introduced into the dirt adhering portion of the sensor to remove the dirt adhering to the sensor.
According to the above-mentioned dirt removal method, since a gas-liquid mixed flow in which cleaning water and gas are mixed is sprayed onto the dirt adhesion portion, a stirring force with complicated disturbance is generated, and the adhered dirt is peeled off and extruded. There is an effect.

  Moreover, the dirt removal method according to the present invention includes the light transmitted from the light projecting unit to the measured water, the transmitted light transmitted through the measured water, and the suspended matter contained in the measured water. When cleaning dirt of a concentration sensor provided with a light receiving unit that receives at least one of the scattered light scattered by the reflected light and the reflected light reflected by the suspension, a gap between the light projecting unit and the light receiving unit is obtained. A gas-liquid mixed flow obtained by mixing cleaning water having a smaller impurity content than the water to be measured and gas is introduced to remove dirt adhering to the concentration sensor.

  According to the above-described dirt removal method, a cleaning liquid in a gas-liquid mixed state in which, for example, air, carbon dioxide gas, oxygen gas, nitrogen gas or argon gas is mixed with clean cleaning water is ejected to the light projecting unit and the light receiving unit of the sensor. To do. That is, the above-described method for removing dirt generates a stirring force with complicated disturbance by making the cleaning liquid into a gas-liquid mixed flow, and obtains a force for peeling off the suspended matter attached to the concentration sensor. In addition, the gas-liquid mixed flow creates a diffusing force in the process of bubbles becoming larger, and has an effect of pushing out the suspended matter separated from the concentration sensor by washing. In addition, by introducing cleaning water that is cleaner than the water to be measured, it is possible to enhance the effect of peeling off the suspension adhering to the sensor and to suppress reattachment of the separated suspension. Therefore, the dirt removing method described above effectively removes dirt attached to the sensor by the gas (bubbles) contained in the gas-liquid mixed flow in addition to the clean washing water forming the gas-liquid mixed flow. .

Further, the dirt removing method according to the present invention introduces a gas-liquid mixed flow between the light projecting unit and the light receiving unit in order to clean the light projecting unit and the light receiving unit of the concentration sensor. The gas-liquid mixed flow is a swirl flow swirling between the light projecting unit and the light receiving unit.
In the above-described dirt removal method, the cleaning water in the gas-liquid mixed state is introduced into the light projecting unit and the light receiving unit of the concentration sensor while swirling. For this reason, it becomes possible to remove the dirt adhering to the light projecting part and the light receiving part of the sensor effectively by the swirl flow.

In the dirt removing method according to the present invention, the gas-liquid mixed flow is introduced between the light projecting unit and the light receiving unit via a plurality of jet nozzles. The plurality of injection nozzles are arranged with their injection directions shifted from each other, and generate a swirling flow that swirls between the light projecting unit and the light receiving unit by a gas-liquid mixed flow injected from each injection nozzle. ing.
Further, in the dirt removing method according to the present invention, it is desirable that the plurality of spray nozzles are arranged by shifting the positions of the spray ports in the radial direction within the same horizontal plane.

  In the above-described dirt removal method, the gas-liquid mixed flow ejected from the plurality of nozzles to the sensor is arranged to generate a swirl flow more effectively. Therefore, the dirt removing method described above can create a swirling flow that is effectively swirled in the vicinity of the sensor, and can remove dirt attached to the sensor by the swirling flow.

  In the above-described method for removing dirt according to the present invention, since a gas-liquid mixed flow in which washing water and gas are mixed is introduced into the dirt adhering portion of the sensor, in addition to washing with clean washing water, complicated air bubbles are introduced. A stirring force accompanied by a turbulence can be generated, and the adhering suspension can be peeled off and extruded (Claim 1). Moreover, in the dirt removal method of the present invention described above, since a gas-liquid mixed flow in which cleaning water and gas are mixed is introduced between the light projecting unit and the light receiving unit, the gas contained in clean cleaning water is used. Dirt adhered to the sensor by forming bubbles can be removed (claim 2). As a result, the density sensor can always ensure high detection accuracy.

In the dirt removal method according to the present invention, the gas-liquid mixed flow is a swirl flow that swirls between the light projecting unit and the light receiving unit. For this reason, the cleaning water in the gas-liquid mixed state swirls on the light projecting surface and the light receiving surface of the sensor, and the dirt adhering to the sensor surface can be more effectively removed.
Specifically, the swirling flow is introduced between the light projecting unit and the light receiving unit via a plurality of jet nozzles, and the jet nozzles are arranged with a phase difference by shifting the jet direction from each other ( Claim 4). For this reason, the gas-liquid mixed flow ejected from each ejection nozzle becomes a swirl flow that swirls between the light projecting unit and the light receiving unit of the sensor, and it is possible to effectively remove the dirt adhering to the sensor.

  Further, in the method for removing dirt according to the present invention, the plurality of spray nozzles are arranged by shifting the positions of the spray ports in the radial direction within the same horizontal plane. In the concentration sensor in which the portion is housed, it is possible to create a swirl flow that effectively swirls the water flow in the vicinity of the sensor, and it is possible to remove dirt attached to the sensor by the swirl flow ( Claim 5).

Hereinafter, a dirt removal method according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing only the main configuration of a suspension concentration meter to which the soil removing method according to the present invention is applied. In this figure, reference numeral 10 denotes a nozzle for injecting a gas-liquid mixed flow, which will be described later, into measured water (not shown in FIG. 1). Reference numeral 5 denotes a suspension of measured water that is immersed in the measured water. It is a part of a transmitted light type sensor that detects an object concentration. Incidentally, the gas-liquid mixed flow ejected from the nozzle 10 is a two-phase fluid in which cleaning water and gas are mixed. The suspension concentration meter is provided with a cleaning liquid tank 11 that holds a cleaning liquid for cleaning the sensor 5. In the cleaning liquid tank 11, for example, clean cleaning water W is stored. The cleaning water W stored in the cleaning liquid tank 11 is pressurized by a water pump 12 that pressurizes to a predetermined pressure. The suspension concentration meter is provided with a compression pump 13 for compressing air A and a pressure tank 14 for temporarily storing the air A compressed by the compression pump 13.

  The water 17 compressed by the water pump 12 and the air A compressed by the compression pump 13 are mixed with the water 17 and the compressed air A through the water control valve 15 and the air control valve 16, respectively. To be sent to. The mixer 17 plays a role of mixing the cleaning water W and the air A to generate a gas-liquid mixed state (two-phase state) fluid (gas-liquid mixed liquid). The gas-liquid mixed solution generated by the mixer 17 is injected from the nozzle 10 to the transmitted light type sensor 5 that detects the suspension concentration of the measured water M by being immersed in the measured water M.

In general, the dirt removing method according to the present invention for removing dirt from the sensor as described above is characterized in that the gas-liquid mixed liquid obtained by mixing the washing liquid and the gas in advance is used as the sensor washing liquid. The gas / liquid mixture is jetted onto the sensor as a swirling flow to clean the sensor.
The dirt removal method according to the present invention having such characteristics will be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram showing a sensor unit of the transmitted light type suspension concentration meter. In this figure, reference numeral 5 denotes the above-mentioned transmitted light type sensor, and an optical fiber 7 that guides light irradiated from a light emitting unit (not shown) into the measured water M and irradiates the measured water M from its end face. I have. The end face of the optical fiber 7 forms a light projecting unit 1 that irradiates the water to be measured M with light. An end surface of another optical fiber 7 is provided at a position facing the light projecting unit 1. This optical fiber 7 forms the light receiving part 2 which receives the light irradiated from the light projecting part 1 to the water M to be measured from its end face. The light received from the light receiving unit 2 is guided to a concentration measuring unit (not shown) by the optical fiber 7 and becomes a detection signal for measuring the concentration of the suspended matter in the measurement target water M.

  The above-described nozzle 10 is provided in the vicinity of the light projecting unit 1 and the light receiving unit 2 so that a gas-liquid mixed flow containing the cleaning liquid W is blown from the tip of the nozzle 10 to the light projecting unit 1 and the light receiving unit 2. It has become. That is, in the concentration sensor to which the dirt removing method according to the embodiment of the present invention is applied, a fluid (a mixture of cleaning liquid and gas) from the nozzle 10 to the light projecting unit 1 and the light receiving unit 2 constantly or periodically. By spraying the gas-liquid mixed flow), dirt due to the suspended matter adhering to the light projecting unit 1 and the light receiving unit 2 is removed.

  In the transmitted light type optical suspension concentration meter, a part of the light that reaches the light receiving unit 2 by the suspended matter contained in the measured water M is irradiated by the light irradiated from the light projecting unit 1 to the measured water M. Blocked. Therefore, the higher the suspension concentration of the water to be measured M, the lower the rate at which the light irradiated from the light projecting unit 1 reaches the light receiving unit 2 due to the suspension contained in the water to be measured M. This decreasing ratio is proportional to the concentration of the suspension contained in the water M to be measured. The optical suspension concentration meter is a measuring device that detects the suspension concentration of the water M to be measured based on such an operation principle. However, when the suspended matter contained in the water to be measured M adheres to the light projecting unit 1 or the light receiving unit 2 of the suspension concentration meter configured as described above, the light reception level reaching the light receiving unit 2 is lowered. Therefore, the true value of the suspension concentration of the water M to be measured cannot be obtained, and a measurement error is caused by the suspension adhering to the light projecting unit 1 and the light receiving unit 2.

  For this reason, the dirt removing method according to the present invention sprays the gas-liquid mixed flow containing the cleaning liquid from the nozzle 10 to the light projecting unit 1 and the light receiving unit 2 constantly or periodically. This removes dirt due to suspended matter adhering to the light receiving unit 2. Incidentally, the gas-liquid mixed flow blown from the nozzle 10 to the light projecting unit 1 and the light receiving unit 2 is cleaning water containing air A in addition to clean cleaning water W. Therefore, compared with the case where washing water W or air A is added individually, the ability to remove the suspended matter attached to the light projecting unit 1 or the light receiving unit 2 is high. That is, by making the cleaning liquid into a gas-liquid mixed flow, a stirring force with complicated disturbance is generated, and a force for peeling off the suspended matter attached to the light projecting unit 1 and the light receiving unit 2 is obtained. That is, by introducing cleaning water that is cleaner than the water to be measured, it is possible to enhance the effect of separating the suspended matter attached to the sensor and to suppress the reattachment of the separated suspended matter. In addition, the gas-liquid mixed flow creates a diffusing force in the process of bubbles becoming larger, and has an effect of pushing out the suspended matter separated from the light projecting unit 1 and the light receiving unit 2. For this reason, the dirt removing method according to the present invention can effectively remove the suspended matter adhering to the light projecting unit 1 or the light receiving unit 2, and obtain the true value of the suspended matter concentration of the water M to be measured. Is possible.

  In addition, it is preferable that the gas-liquid mixed flow sprayed on the light projecting unit 1 and the light receiving unit 2 of the sensor is a swirl flow. That is, by rotating the cleaning liquid in the vicinity of the light projecting unit 1 and the light receiving unit 2, it is possible to remove the suspended matter more effectively than when the gas-liquid mixed flow is simply sprayed. Specifically, the transmitted light type sensor 5 is provided with a cylindrical case 6 having an open end as shown in FIGS. 2 and 3 covering the periphery of the light projecting unit 1 and the light receiving unit 2. Incidentally, in FIG. 3, the light projecting unit 1 and the light receiving unit 2 are omitted for easy understanding of the swirl flow.

  As shown in FIG. 3, the nozzle 10 is attached to the case 6 so that the injection port faces the inner wall surface of the case 6. Then, the gas-liquid mixed flow containing the cleaning water W and the air A sprayed from the nozzle 10 into the case 6 generates a swirl flow swirling in the horizontal cross section by the inner wall surface of the case 6. At this time, the gas-liquid mixed flow is directed upward of the case 6 while turning inside the case 6 by buoyancy obtained by the air A contained in the gas-liquid mixed flow.

Incidentally, in order to effectively form a swirl flow in the case 6, two nozzles 10 for injecting a gas-liquid mixed flow are produced in the case 6 in the same direction as shown in FIG. It is desirable to arrange so that. At this time, the pair of nozzles 10 may be arranged by shifting the positions of the respective injection ports in the radial direction within the same horizontal plane.
Moreover, in order to form a swirl flow more effectively, the number of nozzles 10 may be increased to 3, 4, for example. In this case, as shown in FIG. 4B and FIG. 4C, the nozzles 10 for injecting the gas-liquid mixed flow may be arranged in the case 6 so as to generate a swirling flow in the same direction.

  In the above-described dirt removal method, the case 6 covering the periphery of the light projecting unit 1 and the light receiving unit 2 has been described as a cylinder, but a square tube may be used. In this case, the nozzle 10 as shown in FIG. 4D jets the gas-liquid mixed flow horizontally with respect to the liquid surface along the adjacent inner wall surface, so that the gas-liquid mixed flow swirls in the inner wall surface. It is possible to create a swirling flow. Specifically, as shown in FIG. 4D, a plurality of nozzles 10 are provided in the vicinity of the corner portion 7a of the case 6 so that the gas-liquid mixed flow injected from the nozzles 10 is injected along the inner wall surface. By doing so, a swirl flow in which the gas-liquid mixed flow swirls in the case 6 can be formed more effectively. When a plurality of nozzles 10 are provided in this way, instead of changing the angle between the nozzles 10 to generate a swirling flow, the water pump 12 has the same pressure and different nozzle diameters. Each nozzle diameter is the same, and a phase difference can be produced by varying the pressure or flow velocity, and a swirl flow with a gas-liquid mixed state can be formed.

Further, as shown in FIG. 3, each nozzle can be installed by shifting the position in the vertical direction or changing the angle of each nozzle. By applying such a device, more intense stirring and swirling flow can be generated, and a better cleaning effect can be produced.
Thus, in the dirt removing method according to the present invention, since a gas-liquid mixed flow in which cleaning water and gas are mixed is introduced between the light projecting unit 1 and the light receiving unit 2, light is projected by this gas-liquid mixed flow. A stirring force with complicated disturbance is generated between the part 1 and the light receiving part 2, and a force for peeling off the suspended matter attached to the light projecting part 1 and the light receiving part 2 can be obtained. In addition, the gas-liquid mixed flow creates a diffusing force in the process of increasing the size of the bubbles, and obtains an effect of pushing out the suspended matter separated from the light projecting unit 1 and the light receiving unit 2. For this reason, the dirt removing method according to the present invention can effectively remove the suspended matter attached to the light projecting unit 1 or the light receiving unit 2.

In the dirt removal method according to the present invention, the gas-liquid mixed flow is a swirl flow that swirls between the light projecting unit and the light receiving unit. For this reason, the dirt adhering to the sensor surface can be more effectively removed by the swirling flow of the light projecting surface and the light receiving surface of the sensor.
Further, the swirl flow introduced into the light projecting unit 1 and the light receiving unit 2 is specifically introduced between the light projecting unit and the light receiving unit through a plurality of jet nozzles, and the jet nozzles are in the jet direction with respect to each other. Are arranged with a phase difference shifted from each other. For this reason, the gas-liquid mixed flow ejected from each ejection nozzle becomes a swirl flow swirling between the light projecting unit and the light receiving unit of the sensor, and the dirt attached to the sensor can be removed.

  Further, in the method for removing dirt according to the present invention, the plurality of spray nozzles are arranged by shifting the positions of the spray ports in the radial direction within the same horizontal plane. In the case of a concentration sensor in which the part is controlled, it is possible to create a swirling flow that effectively swirls the water flow in the vicinity of the sensor, and it is possible to effectively remove dirt attached to the sensor by the swirling flow. .

  Furthermore, in the embodiment described above, the gas-liquid mixed flow containing air is ejected from the ejection nozzle, but it may be carbon dioxide, nitrogen gas, argon gas or the like in addition to air. In the case where there is a possibility that the characteristics of the water to be measured may be changed by jetting air to the water to be measured M, the influence of the dirt removal can be obtained by selecting an appropriate gas (for example, an inert gas). Can be eliminated.

  Of course, the method for removing dirt according to the present invention can be applied to a sensor immersed in water to be measured such as a suspension, such as a pH meter, a COD meter, and a BOD meter, in addition to the concentration sensor described above. There is a great effect in practical use.

The block diagram which shows schematic structure of the optical suspension concentration meter to which the dirt removal method which concerns on this invention is applied. Schematic which shows the permeation | transmission type | mold sensor vicinity of the optical turbidity concentration meter to which the dirt removal method which concerns on this invention is applied. The figure which shows the swirl | vortex flow of the gas-liquid mixed flow made by the nozzle attached to the case of the optical turbidity concentration meter shown in FIG. The figure which shows the modification of the nozzle attached to the case of the optical turbidity concentration meter shown in FIG. The block diagram which shows schematic structure of the conventional optical turbidity concentration meter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Nozzle 11 Cleaning liquid tank 12 Water pump 13 Compression pump 14 Pressure tank 15 Washing water control valve 16 Air control valve 17 Mixer

Claims (5)

When removing dirt from the sensor that is installed in the water to be measured consisting of suspension and measures the physical properties and the amount of impurities of the water to be measured,
A dirt removing method comprising introducing a gas-liquid mixed flow in which cleaning water and gas are mixed into a dirt attaching portion of the sensor to remove dirt attached to the sensor. Transmitted light that has passed through the measurement water of light irradiated into the measurement water from the light projecting unit, scattered light scattered by the suspension contained in the measurement water, and reflected light reflected by the suspension When removing dirt from a density sensor having a light receiving unit that receives at least one of
A dirt removing method comprising introducing a gas-liquid mixed flow obtained by mixing cleaning water and gas between the light projecting part and the light receiving part to remove dirt adhered to the concentration sensor. The introduction of the gas-liquid mixed flow between the light projecting unit and the light receiving unit cleans the light projecting unit and the light receiving unit of the concentration sensor,
The dirt removal method according to claim 2, wherein the gas-liquid mixed flow is a swirl flow swirling between the light projecting unit and the light receiving unit. The gas-liquid mixed flow is introduced between the light projecting unit and the light receiving unit via a plurality of injection nozzles,
The plurality of injection nozzles are arranged with their injection directions shifted from each other, and a swirl flow that swirls between the light projecting unit and the light receiving unit is generated by a gas-liquid mixed flow injected from each injection nozzle. 4. The dirt removing method according to claim 1, wherein dirt attached to the density sensor is removed.   The dirt removing method according to claim 4, wherein the plurality of spray nozzles are arranged by shifting the positions of the spray ports in the radial direction within the same horizontal plane.

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