Flocculation state monitoring sensor

Abstract

Provided is a flocculation state monitoring sensor with which blockage of an ejecting part which ejects a gas towards a light emitting part and a light receiving part can be prevented, and which performs stable monitoring. A flocculation state monitoring sensor comprising: a light emitting part which irradiates laser light towards a measuring region which measures a flocculation state; and a light receiving part which receives light scattered along a direction which intersects with a direction along an optical axis of said light emitting part, wherein the light emitting part and the light receiving part are cleaned by air being ejected from nozzles theretowards. A small amount of air is provided to the nozzles between cleaning periods to purge floc, etc.

Claims

1. A flocculation state monitoring sensor comprising: a light emitting part configured to radiate light toward a measuring region in which a flocculation state is measured; a light receiving part configured to receive light scattered in a direction crossing an optical axis direction of the light emitting part; a nozzle for cleaning the light emitting part configured to eject a gas toward the light emitting part; a nozzle for cleaning the light receiving part configured to eject a gas toward the light receiving part; and a control means configured to control ejection of the gas from each of the nozzles, wherein the control means performs control to execute a cleaning period in which the gas is ejected toward the light emitting part from the nozzle for cleaning the light emitting part or the gas is ejected toward the light receiving part from the nozzle for cleaning the light receiving part, and a purging period in which a gas is discharged at a lower flow speed than in the cleaning period from the nozzle during a time between cleaning periods for purging water or floc in the nozzle, wherein a time of the purging period is 6 to 50 milliseconds.

2. The flocculation state monitoring sensor according to claim 1, wherein the nozzles supply gases through electromagnetic valves, respectively.

3. The flocculation state monitoring sensor according to claim 2, wherein chambers are provided between the nozzles and the electromagnetic valves, respectively.

4. The flocculation state monitoring sensor according to claim 3, wherein a time of the cleaning period is 2 to 10 seconds.

5. The flocculation state monitoring sensor according to claim 4, wherein the cleaning period is performed at a frequency of one time per 5 to 60 minutes, and the purging period is performed at a frequency of one time per 0.5 to 5 minutes.

6. The flocculation state monitoring sensor according to claim 2, wherein a time of the cleaning period is 2 to 10 seconds.

7. The flocculation state monitoring sensor according to claim 6, wherein the cleaning period is performed at a frequency of one time per 5 to 60 minutes, and the purging period is performed at a frequency of one time per 0.5 to 5 minutes.

8. The flocculation state monitoring sensor according to claim 1, wherein a time of the cleaning period is 2 to 10 seconds.

9. The flocculation state monitoring sensor according to claim 8, wherein the cleaning period is performed at a frequency of one time per 5 to 60 minutes, and the purging period is performed at a frequency of one time per 0.5 to 5 minutes.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1a is a schematic cross-sectional view showing a configuration of a flocculation state monitoring sensor according to an embodiment. FIG. 1b is a timing chart showing an operation thereof.

DESCRIPTION OF EMBODIMENTS

(2) Hereinafter, an embodiment will be described with reference to FIGS. 1a and 1b.

(3) A probe 1 that constitutes a flocculation state monitoring sensor has a light emitting part 3 disposed on a tip side of a casing 2 and configured to radiate laser light toward a measuring region S of a flocculation processing liquid (a liquid to which flocculant is added and which is stirred according to necessity). In addition, a light receiving part 4 using a light receiving optical axis in a direction perpendicular to a light receiving optical axis of the light emitting part 3 is provided to face the measuring region S. Transparent plates 3a and 4a are provided on front surfaces of the light emitting part 3 and the light receiving part 4, respectively, and circumferential edge portions of the transparent plates 3a and 4a are sealed water-tightly.

(4) A light emitting circuit 5, a detector circuit 6 and a measuring circuit 7 are provided in the probe 1. The measuring circuit 7 has a timing circuit 8, an A/D converting part 9, a calculating part 10, and the like.

(5) Like Patent Literature 1, laser light radiated from the light emitting part 3 to the measuring region S is scattered by particles in the measuring region S, the scattered light is received by the light receiving part 4, and a flocculation state is measured on the basis of intensity of the received light.

(6) The light emitting circuit 5 transmits an electrical signal having a fixed modulation frequency to the light emitting part according to a signal from the timing circuit and performs laser emission. The light emitting part 3 emits a laser according to a signal from the light emitting circuit 5. The light receiving part 4 receives scattered light generated due to abutting of the laser light with suspended matter in water and converts the scattered light into an electrical signal. The detector circuit 6 removes a modulated element from the electrical signal from the light receiving part 4 and outputs a light receiving voltage according to intensity of the scattered light.

(7) The measuring circuit 7 transmits a signal for emission (a specified frequency modulation wave) to the light emitting circuit 5, converts the signal from the detector circuit 6 into a digital signal, and outputs information related to flocculation through logical operation.

(8) A nozzle housing 12 and a nozzle housing 13 are attached to a tip portion of the probe 1. The nozzle housing 12 is disposed at a side opposite to the light receiving part 4 with the measuring region S sandwiched therebetween. A nozzle 31 configured to eject bubbles toward the transparent plate 3a of the light emitting part 3 and clean the transparent plate 3a using a gas-liquid mixed flow and a nozzle 21 configured to eject bubbles toward the transparent plate 4a of the light receiving part 4 and clean the transparent plate 4a using a gas-liquid mixed flow are provided in the nozzle housing 12.

(9) The nozzles 21 and 31 are continuous with an air supply pipeline 42 via chambers 22 and 32, pipelines 23 and 33, electromagnetic valves 24 and 34, and pipelines 25 and 35. The air supply pipeline 42 is continuous with a compressed air supply source such as a compressor (not shown) or the like via a safety valve 41 and a flexible hose 40.

(10) The electromagnetic valves 24 and 34 are controlled by a valve control circuit 50. Further, the valve control circuit 50 may be mounted on the same circuit board as the measuring circuit 7.

(11) Opening and closing control of the electromagnetic valve 24 will be described with reference to FIG. 1b.

(12) The electromagnetic valve 24 is opened during time t.sub.1 to t.sub.2 (a cleaning period), and the transparent plate 4a of the light receiving part 4 is cleaned by a gas-liquid mixed flow. After the electromagnetic valve 24 is closed at the time t.sub.2, the electromagnetic valve 24 is opened for a short time during time t.sub.3 to t.sub.4 (a purging period), and the water entering the chamber 22 and the nozzle 21 (containing SS) is extruded and purged to the measuring region S.

(13) Time between the time t.sub.1 to t.sub.2 is preferably 2 to 10 seconds normally, and in particular, 3 to 5 seconds. The cleaning period (cleaning between time t.sub.1 to t.sub.2) is preferably performed at a frequency of one time per about 5 to 60 minutes, and in particular, one time per about 10 to 20 minutes.

(14) A time of the purging period of the time t.sub.3 to t.sub.4 is preferably about 6 to 50 milliseconds, and in particular, about 8 to 15 milliseconds. The purging period is preferably performed at a frequency of one time per about 0.5 to 5 minutes, and in particular, one time per 1 to 2 minutes.

(15) Opening and closing of the electromagnetic valve 34 is also preferably performed in the same manner as described above.

(16) A timing of opening the electromagnetic valve 34 and cleaning the transparent plate 3a of the light emitting part may not overlap a cleaning timing of the transparent plate 4a. The purging period of the nozzle 21 and the chamber 22 and the purging period of the nozzle 31 and the chamber 32 may overlap each other or may be deviated from each other.

(17) As described above, after the air is ejected during the time t.sub.1 to t.sub.2, when the electromagnetic valve 24 or 34 is closed, water gradually intrudes into the nozzle 21 or 31, or further, the chambers 22 and 32, as time elapses. Then, the flocculated particles (floc) are formed in the nozzles 21 and 31 or in the chambers 22 and 32 by SS elements in the water that have intruded as they are and dissolved medicals (flocculant). When the floc grows until a diameter of the floc is larger than a diameter of the nozzles 21 and 31, a compressed air ejecting resistance upon cleaning is increased.

(18) In the embodiment, since the remaining water or floc in the nozzles 21 and 31 and the chamber 22 and 32 are purged to the region S by performing the purging period between the cleaning periods, an increase in air ejecting resistance from the nozzles 21 and 31 is prevented, and stable measurement (monitoring) can be performed throughout a long period. In addition, since the purging period is short and a frequency thereof is also small, the monitoring is sufficiently performed. In addition, since the purging period is short, a fluid speed flowing from the nozzles 21 and 31 is reduced during the purging period, there is no or little ejected fluid that abuts the plates 3a and 4a, and thus, the plates 3a and 4a are not damaged or abraded.

(19) In the embodiment, while a purge operation is realized during a short “opening” time of the electromagnetic valve, the purge operation may be realized by a method of providing a resistance material in an air flow path for cleaning, adding a pressure flow path for separate cleaning, or the like. Moreover, in these methods, since it is predicted that the structure is complicated or manufacturing cost is increased in comparison with the present invention, it is clear that the present invention is superior to these methods.

(20) The embodiment is an example of the present invention, and the present invention may have configurations other than the above-mentioned.

(21) While the present invention has been described in detail using the specified aspect, it will be apparent to those skilled in the art that various modifications may be made without departing from the spirit of the present invention.

(22) Priority is claimed on Japanese Patent Application No. 2018-176276, filed Sep. 20, 2018, the content of which is incorporated herein by reference.

REFERENCE SIGNS LIST

(23) 1 Probe 2 Casing 3 Light emitting part 3a, 4a Transparent plate 4 Light receiving part 21, 31 Nozzle 24, 34 Electromagnetic valve