JP2004170298A - Particle state detection probe and particle state detection device - Google Patents

Abstract

[PROBLEMS] To provide a particle state detection probe and a particle state detection apparatus having a simple configuration capable of eliminating a measurement error due to the influence of floc caused by a high flow rate of a water sample and capable of measuring stable aggregation characteristics. I do.
A light projecting unit that irradiates a laser beam during water detection, a light receiving unit that is provided near the light projecting unit and receives the scattered light or the transmitted light, and a region irradiated with the laser beam by the light projecting unit. Supports the light projecting part and the light receiving part in a state where the light receiving area of the scattered light by the light receiving part intersects or receives the laser light transmitted through the test water, and supports the measurement area of the particle state in the water test A member and a cover body provided around the measurement area and through which water sample can enter and exit are provided.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a particle state detection probe and a particle state detection device suitable for determining the state of particles in flocculated water (sample water) containing flocs sampled from the flocculation processing step.
[0002]
[Prior art]
In the purification treatment (water quality improvement treatment) of clean water or industrial water, or sewage or waste water, for example, a flocculant is added to the water to be treated, and a suspended substance in the water to be treated is flocculated. It is realized by solid-liquid separation using a method such as precipitation separation, pressure flotation, centrifugation, sand filtration, and membrane separation. However, the flocculation state of the suspended substance in the flocculated water (sample water) containing floc depends on the quality of the water to be treated (pH and concentration of the suspended substance), the amount of the flocculant added in the flocculation treatment step, and the stirring. It cannot be denied that it changes depending on conditions and the like. By the way, if the coagulation treatment conditions are not set appropriately, this may have a negative effect on the subsequent solid-liquid separation treatment, or may cause deterioration of the quality of the treated water after the solid-liquid separation.
[0003]
Therefore, conventionally, the turbidity of the test sample is measured from the intensity of the scattered light generated by the test when light is irradiated into the test sample, and based on the turbidity, the aggregation state of the suspended substance in the test sample is calculated in real time. It has been proposed to optimize the aggregation conditions in the aggregation treatment step by evaluating the above (for example, see Patent Document 1). In this case, under a stable condition where the flow velocity is equal to or lower than a certain value, the level of the reflection signal by the fine particles shows a level proportional to the turbidity. This is because when the flow rate of the treated water is low, the frequency of appearance of large flocs is sufficiently smaller than the frequency of appearance of fine particles. Therefore, the frequency (area ratio) of the fine particles appearing per unit time in the detection area is proportional to the concentration of the suspension.
[0004]
Therefore, the sedimentation of the floc formed during the coagulation treatment of the water to be treated, the turbidity (residual turbidity) after the floc settled, the particle size of the formed floc, etc. were measured, and the coagulation conditions were determined based on this information. Has been conventionally performed.
Specifically, the test water in the test container provided in the coagulation tank or the like is introduced into the turbidity meter by a pump to measure the turbidity, and until the test turbidity introduced into the test container becomes a certain value or less. A method has been proposed for measuring the time of (1) and evaluating the state of aggregation (for example, see Patent Document 2).
[0005]
According to this method, a test container provided with an opening is installed in a coagulation tank, and the test water taken in the test container is introduced into a turbidimeter for measurement. For this reason, a pump and sampling means are required. Also, an air supply means is required to replace the water sample in the test container. Further, there is a problem that the apparatus becomes complicated, for example, it is necessary to separately prepare washing water for washing the turbidity meter. The inspection method disclosed in this publication only measures the time required for the turbidity to fall below a certain value, in other words, the sedimentation velocity. That is, turbidity and floc particle size, which are effective evaluation information for evaluating cohesion, cannot be measured.
[0006]
Alternatively, as another means, a method using a flowing ammeter for coagulation control in wastewater treatment has been proposed (for example, see Patent Document 3).
This method measures the flocculation state by the flowing current and detects the charge neutralization state by the inorganic flocculant, so that water is drawn into the cylinder by the piston operation, and the weak current caused by the movement of the charged particles generated at this time. Is measured with a flowing ammeter. Therefore, there is a problem that a mechanism for performing the piston operation is required, and the current caused by the movement of the charged particles is weak, so that it is easily affected by noise. Furthermore, since the measurement object captures an indirect phenomenon called a flowing current, there is a problem that the aggregation state such as a floc diameter and turbidity cannot be directly evaluated.
[0007]
Therefore, the present applicant irradiates a laser beam into the test water, and detects the scattered light generated by the collision of the laser light with the particles in the test water in a minute measurement region, so that the aggregated and unagglomerated substances are generated. An agglutination monitoring device that discriminates each scattered light component from each other and accurately detects the state of the particles in the test water has been proposed (for example, see Patent Document 4). In this device, the first optical fiber that guides the laser light and emits from the end face and the end faces of the second optical fiber that guides the scattered light introduced from the end face to the photoelectric conversion element are brought close to each other, and By attaching to the supporting member such that the central axes of the fiber end faces cross each other, a probe having a minute measurement region set near the end face of the optical fiber is configured. Then, by immersing the probe in the test water, the state (particle number and particle diameter) of the particles in the minute measurement region is detected.
[0008]
[Patent Document 1]
Japanese Unexamined Patent Publication No. Hei 5-505026 [Patent Document 2]
JP-A-10-71304 [Patent Document 3]
JP-A-7-256008 [Patent Document 4]
JP 2002-195947 A
[Problems to be solved by the invention]
By the way, when measuring the state of the particles in the test water in the flowing water state, the frequency of appearance of large flocs in the measurement region of the probe increases due to the stirring action by the flow rate of the test water. That is, it means that the appearance time of the floc in the measurement area of the probe becomes longer. Incidentally, the scattered light is proportional to the number of particles of the suspended substance in the test water, and is proportional to the fourth to sixth power of the particle diameter. That is, the intensity of the scattered light given to the light receiving section by the flocks increases.
[0010]
However, in the above-described agglutination monitoring device, the average value of the detection levels is used to monitor the state of the particles in the test water, so that the influence of the floc described above increases, and the agglutination state is appropriately grasped. There is a problem that cannot be done.
The present invention has been made in view of such circumstances, and its purpose is to irradiate a laser beam during the test water and scattered light generated by collision of the laser light with particles in the test water or the test water. The present invention relates to a probe for detecting the state of a particle that detects a laser beam that passes through the surface, and in particular, can eliminate measurement errors due to the effects of flocs caused by a high flow rate of the water sample and can measure stable aggregation characteristics. An object of the present invention is to provide a particle state detection probe and a particle state detection device having the above-described configurations.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the particle state detection probe according to the present invention is:
For example, a light emitting unit that irradiates a laser beam during water inspection,
A light receiving unit provided near the light emitting unit and receiving scattered light generated by the irradiation of the laser light or transmitted light transmitted through the test water by the irradiation of the laser light,
A measurement area for measuring a particle state in the test water by supporting the light emitting unit and the light receiving unit in a state where the irradiation area of the laser light by the light emitting unit and the light receiving area of the scattered light by the light receiving unit overlap each other. A support member that defines
A cover provided outside the measurement area and through which the water sample can enter and exit.
[0012]
The light projecting unit is a first optical fiber that guides laser light emitted from a light source and emits the laser light from an end face thereof,
The light receiving unit includes a second optical fiber that guides scattered light or transmitted light incident from the end face to the detection unit.
Preferably, the cover body may be configured as a tubular body having both ends opened.
[0013]
Further, the particle state detection device according to the present invention is configured using the particle state detection probe described above,
An air inlet is provided which guides cleaning air supplied from the outside by being pierced into the cover body, and which jets the cleaning air from an outlet provided near a measurement area defined by the support member. And
[0014]
Preferably, the particle state detection device according to the present invention,
A measurement hood in which the upper end of the cover body is closed,
An air inlet that guides cleaning air supplied from the outside by being pierced by the measurement hood, and that blows out the cleaning air from a discharge port provided near a measurement region defined by the support member,
A cleaning air valve provided at the air inlet to permit the inflow of cleaning air;
An exhaust valve for discharging air held inside the measuring hood to the outside is provided.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a probe for detecting a particle state according to an embodiment of the present invention and a particle state detecting device using the probe will be described with reference to the drawings.
This particle state detection device irradiates a laser beam into the test water subjected to, for example, the aggregating process, and scatters light generated by collision of the laser light with the particles in the test water or transmitted light transmitted through the test water. The detection is configured to measure the state of the particles contained in the test water.
[0016]
First, as a first embodiment, a probe for detecting scattered light includes, as schematically shown in FIG. 1, a first optical fiber 1 for irradiating laser light amplitude-modulated at a predetermined frequency into a test water. A second optical fiber 2 for receiving scattered light generated when the laser light collides with particles contained in the test water, and a second pedestal (supporting member) 3 with the fiber end faces brought close to each other. It has a fixed structure.
[0017]
More specifically, the second optical fiber 2 is fixed to the pedestal 3 at a predetermined distance laterally from the optical axis of the laser light emitted from the first optical fiber 1. That is, the end surface (light receiving surface) of the second optical fiber 2 is provided near the end surface of the first optical fiber 1 so as to be curved. Then, a laser beam is applied to a minute area S having a diameter of about 0.2 to 0.4 mm at a portion where the center axes of the end faces of the optical fibers 1 and 2 intersect, and scattered light generated in the area S is received. It is configured as follows. The pedestal 3 also has a role of blocking external light (natural light) entering from above the probe 5 from reaching the region S.
[0018]
Here, the optical fibers 1 and 2 have a core diameter of about 0.1 mm, and the probe 5 has a size of, for example, about 10 to 20 mm as a whole.
Basically, in the particle state detecting probe 5 having the above-described structure, the present invention is characterized in that both ends thereof are open to the outer periphery of the particle state detecting probe 5 as shown in FIG. In that the cover body 9 is provided. The cover body 9 plays a role in greatly reducing the flow rate of the water sample around the minute region S received from the lateral direction of the particle state detecting probe 5 by the flow rate of the water sample.
[0019]
In other words, most of the water sample flows in the lateral direction with respect to the probe 5, but the flow of the probe body 5 in the vicinity of the minute region S can be made extremely gentle by the cover 9.
The flock contained in the test water that has entered the inside of the cover body 9 falls downward due to its own weight. That is, the vicinity of the minute region S of the probe 5 is surrounded by the cover body 9 so as not to be affected by flowing water. In other words, it is possible to effectively suppress the appearance of large flocs in the measurement region of the probe due to the stirring action caused by the flow rate of the water sample. For this reason, the particle state detection probe 5 can measure only the suspended matter that has not been taken into the flocs.
[0020]
FIG. 2 shows the measurement concept of the detection of suspended solids (micro colloid particles) in the test water and the state of particles composed of flocs generated by the aggregation by the particle state detection device using the probe 5 having such a structure. As shown, for example, the light emitting unit 10 outputs a laser beam L amplitude-modulated at a predetermined frequency and irradiates the sample 5 with the probe 5 via the first optical fiber 1 in the probe 5 so that the particles contained in the sample 5 The detection is performed by the detection unit 20 receiving the scattered light generated when the laser light collides, via the second optical fiber 2 of the probe.
[0021]
The light emitting unit 10 electrically connects a laser oscillator 11 such as a laser diode that oscillates and outputs a laser beam L having a wavelength of 630 nm, and the laser beam L that is oscillated and output by the laser oscillator 11 at 70 to 150 kHz (for example, 95 kHz). And an amplitude modulator 12 such as a function generator that performs amplitude modulation (AM modulation). The detection unit 20 includes a photoelectric converter 21 such as a phototransistor that generates an electric signal corresponding to the amount of received scattered light S (received light intensity), and only a frequency component whose amplitude is modulated from the photoelectric conversion output as described above. And a detector 24 that detects the signal F of the amplitude-modulated frequency component obtained by amplifying the output of the band-pass filter 22 via an amplifier 23 and obtains an envelope component E thereof. And is provided.
[0022]
Note that the amplitude modulation of the laser light L plays a role of distinguishing from extraneous light such as natural light mixed in the test water by modulating scattered light generated by the irradiation of the laser light L into the test water. Therefore, by filtering the output of the photoelectric converter 21 through the band-pass filter 22, it is possible to extract only the component of the scattered light by the laser light L irradiated into the test water as the frequency component of the amplitude modulation. Become.
[0023]
Further, in the particle state detecting device according to another embodiment of the present invention, as shown in the embodiment in FIG. 3, the upper end portion of the cover 9 provided around the particle state detecting probe 5 is closed. A measurement hood 30 is provided. The measurement hood 30 has an air introduction hole 6 for ejecting air supplied from an external air supply source (not shown) to each end face of the optical fibers 1 and 2 and the vicinity of the minute area S. An exhaust hole 41 for discharging air in the hood to the outside and an exhaust valve 42 for controlling the exhaust are provided.
[0024]
The air introduction hole 6 is provided with an ejection port 7 formed in the measurement hood 30 and ejecting air in close proximity to each end face of the optical fibers 1 and 2. Connected to the air supply. The air supply passage 45 has an air supply valve 46 for controlling the air flowing into the measurement hood 30 as described later. In particular, the ejection port 7 provided in the measuring hood 30 is set so as to eject air to each end face of the optical fibers 1 and 2, and each ejection face of the optical fibers 1 and 2 is ejected by the air jet. It also plays a role in removing dirt adhering to.
[0025]
When the thus configured probe for detecting a particle state is applied to the particle state detection device shown in FIG. 2 and, for example, the treatment water in the flocculation tank is measured, first, the air is supplied from the air supply source through the air introduction hole 6. The supplied air is ejected from the ejection port 7. Then, the air pushes away the water sample and reaches the end faces of the optical fibers 1 and 2 and the minute area S, and the light projecting unit 2a and the light receiving unit 1a of the probe for detecting the state of particles are washed. Then, all the water sampled in the hood 30 is discharged out of the hood 30 by the air that has flowed into the measurement hood 30 from the ejection port 7.
[0026]
Preferably, the amount of air supplied from the air supply source is set to a time sufficient to discharge all the test water present in the measurement hood 30.
Then, the valve control unit 40 closes the air supply valve 46 after discharging the water sample stored in the measurement hood 30 to the outside of the hood 30. Next, the valve control unit 40 opens the exhaust valve 42. Then, the treated water in the coagulation tank flows from the lower end of the measuring hood 30. This treated water eventually reaches the particle state detection probe 5 provided in the measurement hood. At this time, since the detection unit 20 can detect the change in the light reception signal of the probe 5, the suspended substance (fine colloid particles) in the treated water (water sample) can be captured from this point in the same manner as in the above-described particle state detection device. Alternatively, the detection of the state of particles composed of flocs generated by the aggregation is started.
[0027]
Since the height [h] from the lower end of the measuring hood 30 to the light receiving surface 2a is set in advance, the time [t] from the opening of the exhaust valve 42 to the arrival of the treated water at the light receiving surface 2a is measured. By doing so, the rising speed [v] of the treated water in the probe 5 can be obtained (v = h / t). The floc particle size can be calculated from the floc signal detected by the probe 5 based on the rising speed [v].
[0028]
That is, the rising speed [v ₁ ] of the floc in the probe 5 is determined from the time [t ₁ ] from the arrival of the treated water to the micro region S of the probe 5 until the floc passes through the micro region S. The approximate floc particle size can be determined from the difference between [v] and [v ₁ ].
Thereafter, the treated water flows to the upper limit position in the measuring hood 30. After a lapse of a sufficient time in anticipation of the inflow of the treated water to the upper limit position, the valve control unit 40 closes the exhaust valve 42.
[0029]
By the way, when the treated water flows into the upper limit position in the measuring hood, similarly to the particle state detecting probe 5 provided with the above-mentioned cover body, the treated water in the measuring hood 30 and the inside of the coagulation tank other than the portion are treated. Replacement with treated water is reduced. For this reason, the sedimentation starts from the floc having high sedimentation property, that is, the floc that has grown greatly contained in the measuring hood 30. Then, after a while, fine suspended matter and small flocs which hardly settle remain in the measuring hood 30. At this time, the detection unit 20 can measure the number of microcolloid particles excluding the influence of flocs, that is, the scattered light intensity proportional to the number of unaggregated colloid particles, by averaging the detection signals of the probe 5. it can. Further, the detection unit 20 measures the time from when the exhaust valve 42 is closed until the state of the average turbidity is reached, so that the sedimentation speed of the floc can be measured.
[0030]
By repeating the measurement in such a procedure, it is possible to grasp the treatment state of the treated water in the flocculation tank in real time.
Further, the above-described embodiment exemplifies a case where one end of the measurement hood 30 is located above the water test surface. However, the particle state detection device according to the present invention measures even in a state immersed in test water. Is possible. In this case, the exhaust valve 42 may be closed when the water level in the measurement hood 30 reaches a predetermined constant water level or is completely filled with the water level.
[0031]
Thus, according to the particle state detection device using the particle state detection probe configured as described above, since the cover body 9 or the measurement hood 30 is provided around the probe 5, for example, the processing in the aggregation tank is performed. In the measurement of water, the scattered light intensity of the sample can be detected without being affected by flowing water. Further, the particle state detecting device can measure the sedimentation speed and particle size of flocs.
[0032]
Therefore, it is possible to correctly measure the characteristic value for evaluating the cohesion of the coagulation tank. In addition, since the water sample in and out of the measurement hood 30 can be opened and closed by opening and closing the air valves (42, 46), it can be performed without using a conventional piston drive mechanism.
Furthermore, it is possible to clean the end faces of the optical fibers 1 and 2 using the air ejected from the ejection port 7 to remove dirt attached to the end faces. Therefore, the probe can be kept in a clean state, and it is possible to achieve a great effect in practical use such as easy maintenance.
[0033]
Next, as a second embodiment, a particle state detection probe that detects transmitted light will be described. As shown schematically in FIG. 4, the probe has a first optical fiber 1 for irradiating laser light into the test water and a second optical fiber 1 for receiving the transmitted light transmitted by the laser light through the test water. The two optical fibers 2 are fixed to a predetermined pedestal (supporting member) 3 with their fiber end faces closely facing each other.
[0034]
As schematically shown in FIG. 4A, the optical fibers 1 and 2 are respectively curved so that the central axes at the end faces of the respective fibers coincide with each other, and are fixed to the pedestal 3 so as to face each other. Then, a laser beam is applied to a small area S having a diameter of about 0.2 to 0.4 mm near the center axis of each end face of the optical fibers 1 and 2, and the transmitted light transmitted through the area S is received. Is done. The pedestal 3 also has a role of blocking external light (natural light) entering from above the probe 5 from reaching the region S.
[0035]
Alternatively, as shown in FIG. 4B, the optical fiber 2 on the light receiving section side is curved and is fixed to the pedestal 3 so that the end face of the optical fiber 1 and the center axis thereof coincide with each other. . And it is comprised so that the transmitted light which permeate | transmits the micro area | region S may be received.
If the radius of curvature of the curved portion of the optical fiber shown in FIG. 4A or 4B cannot be reduced and it is difficult to reduce the size of the probe, for example, as shown in FIG. The transmitted light may be obtained by using a prism 7 or the like in the curved portion.
[0036]
As described above, in the above-described probe for detecting a particle state using transmitted light, similarly to the probe using scattered light described above, the cover body 9 (not shown in FIG. ) Is provided. That is, since the cover body 9 is provided in the vicinity of the minute region S, the sedimentation speed and the particle size of the floc in the treated water can be determined regardless of the flow rate of the sampled water even if the probe utilizes the transmitted light. It is possible to stably measure the distribution and the turbidity of the unaggregated colloid particles.
[0037]
In the above-described embodiment, the aggregating process is described as an example. However, the present invention can be applied to a biological treatment tank (aeration tank). In this case, it is possible to stably measure the sedimentation velocity and the like of the sludge in the aeration tank.
In addition, the present invention can be variously modified and implemented without departing from the gist thereof.
[0038]
【The invention's effect】
As described above, according to the present invention, since the cover or the measuring hood is provided around the detection area of the probe, the turbidity of the sample and the floc of the floc are not affected by the flow rate of the sample. It becomes possible to measure the sedimentation velocity and the particle size. In addition, the entry and exit of water sample in the measurement hood can be easily performed by opening and closing the air valve.
[0039]
Further, by providing the function of cleaning the fiber end face with air ejected near the tip of the probe, it is possible to reliably and reliably detect the state of particles in the sample while removing dirt attached to the fiber end face. Therefore, a great effect in practical use can be obtained, for example, the measurement accuracy can be easily increased.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a particle state detection probe according to the present invention, which detects scattered light in a minute region S accompanying aggregation of a suspended substance (fine colloid particles).
FIG. 2 is a schematic configuration diagram showing a particle state detection device using the particle state detection probe according to the present invention.
FIG. 3 is a schematic configuration diagram showing a particle state detection device according to another embodiment using the particle state detection probe according to the present invention.
FIG. 4 is a schematic configuration diagram of a particle state detection probe for detecting transmitted light according to another embodiment of the present invention.
[Explanation of symbols]
1 First optical fiber (light emitting unit)
2 Second optical fiber (light receiving unit)
3 pedestal (support member)
5 Probe 9 Cover body 10 Light emitting unit 20 Detecting unit 30 Measurement hood 40 Valve control unit 41 Exhaust hole 42 Exhaust valve 45 Air supply path 46 Air supply valve

Claims (5)

A light emitting unit that irradiates a laser beam during the test water,
A light receiving unit provided near the light emitting unit and receiving scattered light generated by the irradiation of the laser light or transmitted light transmitted through the test water by the irradiation of the laser light,
A measurement area for measuring a particle state in the test water by supporting the light emitting unit and the light receiving unit in a state where the irradiation area of the laser light by the light emitting unit and the light receiving area of the scattered light by the light receiving unit overlap each other. A support member that defines
A cover provided outside the measurement area and through which the water sample can enter and exit. The light emitting unit is a first optical fiber that guides laser light emitted from a light source and emits the laser light from an end face thereof,
2. The probe according to claim 1, wherein the light receiving unit includes a second optical fiber that guides scattered light or transmitted light incident from an end surface of the light receiving unit to the detection unit. 3. The particle state detection probe according to claim 1, wherein the cover body has a cylindrical shape with both ends opened. A particle state detection device configured using the particle state detection probe according to any one of claims 1 to 3,
An air inlet for guiding the cleaning air supplied from the outside by being pierced in the cover body and ejecting the cleaning air from an outlet provided near a measurement area defined by the support member is provided. Particle state detection device. A particle state detection device configured using the particle state detection probe according to any one of claims 1 to 3,
A measurement hood in which the upper end of the cover body is closed,
An air inlet that guides cleaning air supplied from the outside by being pierced by the measurement hood, and that blows out the cleaning air from a discharge port provided near a measurement region defined by the support member,
A cleaning air valve provided at the air inlet to permit the inflow of cleaning air;
An exhaust valve for discharging air held inside the measuring hood to the outside, and a particle state detecting device.

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