WO2013108413A1 - Ultrasonic concentration meter for measuring sludge concentration, and sludge treatment system - Google Patents

Ultrasonic concentration meter for measuring sludge concentration, and sludge treatment system Download PDF

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Publication number
WO2013108413A1
WO2013108413A1 PCT/JP2012/051897 JP2012051897W WO2013108413A1 WO 2013108413 A1 WO2013108413 A1 WO 2013108413A1 JP 2012051897 W JP2012051897 W JP 2012051897W WO 2013108413 A1 WO2013108413 A1 WO 2013108413A1
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WIPO (PCT)
Prior art keywords
sludge
concentration
ultrasonic
frequency
densitometer
Prior art date
Application number
PCT/JP2012/051897
Other languages
French (fr)
Japanese (ja)
Inventor
本多祐二
宮本年昭
牧野匡伸
松下尚孝
舞田雄一
張相福
權進熙
Original Assignee
本多電子株式会社
コリア ウォーター リソーシズ コーポレーション
リーテック株式会社
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Application filed by 本多電子株式会社, コリア ウォーター リソーシズ コーポレーション, リーテック株式会社 filed Critical 本多電子株式会社
Priority to KR1020127003677A priority Critical patent/KR101409043B1/en
Priority to PCT/JP2012/051897 priority patent/WO2013108413A1/en
Publication of WO2013108413A1 publication Critical patent/WO2013108413A1/en

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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/02—Biological treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/12—Treatment of sludge; Devices therefor by de-watering, drying or thickening
    • C02F11/13—Treatment of sludge; Devices therefor by de-watering, drying or thickening by heating
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • C02F11/18—Treatment of sludge; Devices therefor by thermal conditioning
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/006—Regulation methods for biological treatment
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/02—Analysing fluids
    • G01N29/032—Analysing fluids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/222—Constructional or flow details for analysing fluids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
    • G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/001—Upstream control, i.e. monitoring for predictive control
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/01—Density
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/024—Mixtures
    • G01N2291/02416—Solids in liquids
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02809—Concentration of a compound, e.g. measured by a surface mass change
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/028—Material parameters
    • G01N2291/02818—Density, viscosity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/20—Sludge processing

Definitions

  • the present invention relates to an ultrasonic densitometer for measuring the concentration of sludge based on the attenuation amount of ultrasonic waves propagating through the sludge, and a sludge treatment system including the ultrasonic densitometer.
  • ultrasonic densitometers that measure the concentration of liquid using ultrasonic waves have been put into practical use.
  • the ultrasonic densitometer can keep costs low as compared with a densitometer using an electromagnetic wave or a laser.
  • the ultrasonic densitometer can measure the concentration of suspended matter contained in the liquid, and further has an advantage that the concentration can be measured regardless of the transparency and liquid color of the liquid. For this reason, ultrasonic densitometers are used to measure the sludge concentration in sewer facilities (see, for example, Patent Document 1).
  • ultrasonic waves of two types are propagated to the measured sludge. And based on the attenuation amount of the ultrasonic wave of each frequency, the attenuation amount by the bubble contained in the measurement sludge is corrected, and the concentration of the measurement sludge is calculated.
  • the sludge concentration when the sewerage facility is operated normally, the sludge concentration is about 3% to about 11%, but when the treatment of the sewerage facility becomes abnormal, the sludge concentration may be, for example, 3% or less. .
  • the 1 MHz ultrasonic wave hardly attenuates, and the sludge concentration measuring device of Patent Document 1 has a problem that the accurate sludge concentration cannot be measured.
  • the sludge concentration may increase. In this case, the ultrasonic wave of 3 MHz is surely reflected by the foreign matter in the sludge, and the attenuation corresponding to the sludge concentration is saturated, so that the sludge concentration cannot be measured accurately.
  • sludge treatment can be performed in each treatment tank without any problems even if an abnormality occurs in the sludge concentration, so there was no need to perform accurate sludge concentration management.
  • the processing capacity is reduced by optimizing the processing capacity.
  • Such a treatment facility is required to efficiently perform sludge treatment by accurately performing sludge concentration management in each treatment tank.
  • the present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic densitometer for sludge concentration measurement that can accurately measure the sludge concentration. Another object is to provide a sludge treatment system capable of measuring sludge concentration accurately and performing sludge treatment efficiently.
  • the invention according to claim 1 is directed to an ultrasonic transmission means capable of transmitting ultrasonic waves having different frequencies in the measured sludge, and receiving the ultrasonic waves propagated in the measured sludge.
  • an ultrasonic densitometer that calculates the amount of ultrasonic attenuation from the intensity of the received signal of the ultrasonic wave, and calculates the sludge concentration of the sludge to be measured from the ultrasonic attenuation amount, When the concentration determination means determines whether the sludge concentration has reached a set concentration value corresponding to the automatic switching transition point of the frequency, and when the concentration determination means determines that the set concentration value has been reached,
  • the gist thereof is an ultrasonic densitometer for measuring the concentration of sludge, characterized by comprising a measuring frequency switching means for automatically switching the frequency of the ultrasonic wave transmitted by the sound wave transmitting means to another one.
  • the sludge concentration is calculated.
  • the frequency of the ultrasonic wave used for is automatically switched. In this way, when the sludge concentration changes, the sludge concentration can be accurately obtained using the ultrasonic wave having the optimum frequency according to the sludge concentration. Specifically, when the sludge concentration is low, if the frequency of the ultrasonic wave is too low, the ultrasonic wave is not reflected on the foreign matter in the sludge, and attenuation according to the sludge concentration is difficult to occur.
  • the sludge concentration is high, if the frequency of the ultrasonic wave is too high, the ultrasonic wave is surely reflected by the foreign matter in the sludge, and the attenuation corresponding to the sludge concentration is saturated. Accordingly, when the sludge concentration is lower than the set concentration value, the sludge concentration is obtained using high frequency ultrasonic waves. On the other hand, when the sludge concentration becomes higher than the set concentration value, switching to a low frequency ultrasonic wave is performed, and the sludge concentration is obtained using the low frequency ultrasonic wave. If the ultrasonic densitometer is configured in this manner, the sludge concentration can be accurately obtained from a low concentration to a high concentration.
  • a second aspect of the present invention is the method according to the first aspect, wherein the measurement frequency switching means is different from the first frequency suitable for measurement in a low concentration region and the first frequency, and has a high concentration.
  • the ultrasonic wave frequency is switched between the second frequency suitable for the measurement of the area and the concentration determination means determines that the sludge concentration decreases and reaches the set concentration value from the high concentration side.
  • the concentration increases when the sludge concentration increases and reaches the set concentration value from the low concentration side.
  • the gist of the invention is to automatically switch the frequency of the ultrasonic wave from the first frequency to the second frequency when the determination means determines.
  • the sludge concentration when the sludge concentration is lower than the set concentration value, the sludge concentration is obtained using the ultrasonic wave of the first frequency suitable for the measurement in the low concentration range, and the sludge concentration is set to the set concentration.
  • the sludge concentration is obtained using ultrasonic waves of the second frequency suitable for measurement in the high concentration range. If the ultrasonic densitometer is configured in this manner, the sludge concentration can be accurately obtained from a low concentration to a high concentration.
  • the gist of the invention described in claim 3 is that, in claim 2, the first frequency is three times the second frequency.
  • the ultrasonic wave of the second frequency when used as the fundamental wave, the ultrasonic wave of the first frequency becomes the third harmonic of the fundamental wave.
  • the piezoelectric elements constituting the ultrasonic transmission means can be vibrated efficiently at each frequency, and ultrasonic waves of each frequency can be efficiently and reliably transmitted from the ultrasonic transmission means.
  • the signal amplification unit further includes a signal amplification unit capable of amplifying and outputting the reception signal of the ultrasonic reception unit and adjusting a gain of the signal amplification.
  • the gist of the means is to automatically adjust the gain of the signal amplification corresponding to the second frequency based on the result of the sludge concentration calculated using the ultrasonic wave of the first frequency.
  • the gain of signal amplification corresponding to the second frequency can be optimized based on the sludge concentration calculated using the ultrasonic wave of the first frequency. In this way, the concentration range that can be measured using the ultrasonic waves of the second frequency can be expanded.
  • a plurality of pairs of the ultrasonic transmission means and the ultrasonic reception means arranged opposite to the ultrasonic transmission means are provided, and the signal amplification means includes the ultrasonic reception means.
  • the gist is to adjust the gain of signal amplification every time.
  • the sludge concentration measured by each ultrasonic transmission means and ultrasonic reception means is determined. By averaging, the measurement error can be kept low. Further, since the gain of signal amplification is adjusted for each ultrasonic receiving means, variations in element characteristics between the ultrasonic transmitting means and the ultrasonic receiving means can be corrected, and the measurement accuracy can be improved.
  • the gist of the invention described in claim 6 is that, in claim 4 or 5, the measurement frequency switching means switches the frequency of the ultrasonic wave after the gain adjustment by the signal amplifying means.
  • the frequency of the ultrasonic wave is switched from the first frequency to the second frequency after the gain of the signal amplification corresponding to the second frequency is adjusted,
  • the sludge concentration can be accurately measured using ultrasonic waves.
  • the gist of the invention described in claim 7 is that, in any one of claims 1 to 6, further comprising a set density value changing means for changing a set density value corresponding to the automatic switching transition point. .
  • the set density value corresponding to the automatic switching transition point is changed by the set density value changing means.
  • the automatic switching transition point can be changed according to the environment in which the ultrasonic densitometer is used (temperature, concentration, etc. of the sludge to be measured), and the ultrasonic frequency is set at an appropriate set concentration value according to the environment. Can be switched.
  • the invention according to claim 8 is the invention according to claim 7, wherein the set density value changing means changes the set density value to a low density side when the gain is adjusted to be low by the signal amplifying means.
  • the gist is to do.
  • the set concentration value can be appropriately changed according to the gain of signal amplification corresponding to the second frequency, and measurement can be performed using the ultrasonic wave of the second frequency.
  • the possible concentration range can be expanded.
  • the invention according to claim 9 performs a water treatment process using a sand basin, an initial settling tank, an aeration tank or a sealed tank, and a final settling tank, and a plurality of types of processing apparatuses including a chemical treatment tank.
  • a sludge treatment system of a sewerage facility that performs a sludge treatment process using a treatment device group, wherein the sludge discharged from the final sedimentation tank is provided in the middle of a pipe that supplies the treatment device group.
  • the ultrasonic concentration meter according to any one of claims 8 and 8, a chemical input amount adjusting means for adjusting an input amount of the chemical to be input to the chemical treatment tank based on the sludge concentration measured by the ultrasonic concentration meter;
  • a sludge treatment system characterized by comprising
  • emitted from the final sedimentation tank of a sewer facility is measured with an ultrasonic densitometer, and the input amount of the chemical
  • concentration is used. It can be adjusted optimally. If it does in this way, a chemical
  • the invention according to claim 10 is the invention according to claim 9, wherein the treatment device group includes a sludge dehydrator, and the operating rate of the sludge dehydrator is determined based on the sludge concentration measured by the ultrasonic densitometer. The gist is to adjust.
  • the operating rate of the sludge dewatering machine is adjusted based on the sludge concentration measured by the ultrasonic densitometer. In this case, since the sludge dewatering machine is operated in an optimum state, the power consumption can be kept low, and the running cost of the sludge treatment system can be reduced.
  • an ultrasonic densitometer that can accurately measure the sludge concentration by automatically switching the frequency of the ultrasonic wave according to the sludge concentration. be able to.
  • the sludge processing system which can measure sludge density
  • the schematic block diagram which shows the sludge processing system of one embodiment.
  • the schematic block diagram which shows an ultrasonic densitometer.
  • the graph which shows the relationship between ultrasonic attenuation and sludge density
  • the flowchart which shows a sludge density
  • the schematic block diagram which shows the sludge processing system of another embodiment.
  • the sludge treatment system 1 of the present embodiment includes a sand basin 2, an initial sedimentation tank 3, an aeration tank 4, a final sedimentation tank 5, and the like as equipment for performing a water treatment process. Furthermore, the sludge treatment system 1 includes treatment devices such as a flotation concentration tank 11, a digestion tank 12, a sludge dehydrator 13, a sludge incinerator 14, and a powder dephosphorization device 15 as treatment device groups for performing a sludge treatment process. I have.
  • Sedimentation basin 2 is an artificial pond that gently drains sewage discharged from households and business establishments to sink and remove trash and earth and sand.
  • the sewage discharged from the settling basin 2 is poured into the first settling tank 3 to remove the small dust that floats, and the sludge W1 (raw sludge) that has settled at the bottom of the first settling tank 3 passes through the pipe 21 to the digestion tank 12.
  • an ultrasonic densitometer 22 is provided in the middle of a pipe 21 that first connects the sedimentation tank 3 and the digestion tank 12, and the concentration of the sludge W ⁇ b> 1 sent to the digestion tank 12 is measured by the ultrasonic densitometer 22. .
  • aeration tank 4 activated sludge containing microorganisms for purifying sewage is mixed with sewage by compressed air. And the organic matter in sewage is decomposed by the action of microorganisms. In addition, it may replace with the method of processing with an aerobic microorganism using the aeration tank 4, and may employ
  • the activated sludge purified from the sewage is submerged, and the supernatant is taken out as treated water W2. Further, the treated water W2 is filtered by passing through a layer of sand to remove suspended matters, and then discharged into the river. A part of the precipitated sludge W1 discharged from the final settling tank 5 is returned to the aeration tank 4 as activated sludge, and the remaining sludge W1 is sent to the floating concentration tank 11.
  • the sludge W1 supplied from the final sedimentation tank 5 is concentrated by raising the pressure, and the concentrated sludge W1 is sent to a digestion tank 12 as a chemical treatment tank.
  • the digestion tank 12 decomposes organic substances in the sludge W1 by anaerobic digestion.
  • methane gas is generated by the decomposition of the organic matter, and the methane gas is collected in a gas tank (not shown) and used as fuel for the sludge incinerator 14 and the like.
  • the sludge W1 treated in the digestion tank 12 contains a lot of moisture, the sludge W1 is sent to the sludge dehydrator 13 and dehydrated. As a result, the soil is reduced in moisture. And after incinerating the thing of a soil state with the sludge incinerator 14, it carries out outside as a raw material of cement or a fertilizer.
  • the waste water discharged from the sludge dehydrator 13 is sent to the powder dephosphorization device 15. And in the powder dephosphorization apparatus 15, the phosphorus contained in the waste water is collect
  • the recovered magnesium ammonium phosphate is sold to a manufacturer as a fertilizer raw material.
  • the digestion tank 12 is provided with a chemical input device 24 (chemical input amount adjusting means) for supplying a chemical.
  • This chemical is a chemical for allowing fine sludge W1 to float and deposit it efficiently.
  • an ultrasonic concentration meter 26 is provided in the middle of the pipe 25 connecting the final sedimentation tank 5 and the floating concentration tank 11, and the sludge W1 (measured object) discharged from the final sedimentation tank 5 by the ultrasonic concentration meter 26 is provided. Sludge concentration of sludge) is measured.
  • the ultrasonic densitometer 26 is electrically connected to the medicine injection device 24.
  • an ultrasonic densitometer 22 provided in the middle of a pipe 21 that initially connects the precipitation tank 3 and the digestion tank 12 is electrically connected to the medicine charging device 24. Then, the sludge concentration data measured by the ultrasonic densitometers 22 and 26 is input to the chemical injection device 24. The medicine feeding device 24 adjusts the amount of medicine to be fed into the digestion tank 12 based on the sludge concentration measured by the ultrasonic densitometers 22 and 26.
  • the sludge concentration data measured by the ultrasonic densitometers 22 and 26 is also input to the sludge dewatering machine 13, and the operating rate of the sludge dewatering machine 13 is adjusted based on the sludge density.
  • the ultrasonic densitometer 26 used in the present embodiment will be described in detail with reference to FIG. Note that the ultrasonic densitometer 22 provided in the pipe 21 that first connects the precipitation tank 3 and the digestion tank 12 also has the same structure as the ultrasonic densitometer 26 of FIG.
  • the ultrasonic densitometer 26 includes a cylindrical tube body 30, four pairs of transmission sensors 31 and reception sensors 32, an ultrasonic oscillator 33, a reception circuit 34, and a signal amplification circuit 35. And a controller 36 and a display device 37.
  • the pipe main body 30 of the ultrasonic densitometer 26 is connected to the pipe 25, and the sludge W1 flows from the upper side to the lower side in FIG.
  • the sensors 31 and 32 are provided at equal intervals along the flow direction of the sludge W1 (the axial direction of the pipe main body 30) on the side wall of the pipe main body 30, respectively. Note that the sensors 31 and 32 are not necessarily provided at equal intervals.
  • the transmission sensor 31 and the reception sensor 32 that are paired are provided at positions facing each other with the flow path of the pipe main body 30 interposed therebetween, and transmit and receive the ultrasonic wave S1 in a direction orthogonal to the flow direction of the sludge W1. I do.
  • the ultrasonic oscillator 33 is connected to the transmission sensor 31, generates drive signals having different frequencies (specifically, a 1 MHz drive signal and a 3 MHz drive signal) and outputs the drive signals to the transmission sensor 31.
  • the frequency of the drive signal is switched based on a control signal output from the controller 36.
  • the transmission sensor 31 as an ultrasonic transmission means transmits an ultrasonic wave S1 of 1 MHz or 3 MHz into the sludge W1 by vibrating with a drive signal of the ultrasonic oscillator 33.
  • the ultrasonic wave S1 which propagated in the sludge W1 is received by the receiving sensor 32 as an ultrasonic wave receiving means.
  • the reception circuit 34 is connected to the reception sensor 32, acquires the reception signal of the ultrasonic wave S ⁇ b> 1 received by the reception sensor 32, and outputs it to the signal amplification circuit 35.
  • the signal amplification circuit 35 as signal amplification means amplifies the reception signal of the ultrasonic wave S1 and outputs it to the controller 36.
  • the signal amplification circuit 35 according to the present embodiment is configured to be able to adjust the gain of signal amplification based on a control signal output from the controller 36.
  • the controller 36 includes a well-known CPU 38 (central processing unit), a memory 39, etc., and the CPU 38 executes a control program using the memory 39 to measure the sludge concentration of the sludge W1 flowing through the pipe body 30. To do. Specifically, the controller 36 obtains an ultrasonic attenuation amount (attenuation amount of the ultrasonic wave S1 propagating through the sludge W1) from the intensity of the received signal of the ultrasonic wave S1. And the controller 36 calculates
  • an ultrasonic attenuation amount attenuation amount of the ultrasonic wave S1 propagating through the sludge W1 from the intensity of the received signal of the ultrasonic wave S1.
  • the controller 36 calculates
  • the conversion table data is obtained for each of the sensors 31 and 32 at the time of factory shipment or the like, and stored in the memory 39 of the controller 36 in advance.
  • the ultrasonic densitometer 26 includes a 4-channel measurement unit (transmission sensor 31 and reception sensor 32). In each measurement unit, the attenuation amount of the ultrasonic wave S1 is obtained, and the remaining one excluding the largest one is excluded.
  • the sludge concentration is obtained using three average values.
  • the controller 36 displays the sludge concentration on the display device 37 and outputs the sludge concentration data to the chemical charging device 24 and the sludge dehydrator 13 of the digestion tank 12.
  • concentration is not limited only to said method, Another method may be sufficient.
  • the ultrasonic densitometer 26 of the present embodiment measures the sludge concentration using the ultrasonic wave S1 of 3 MHz (first frequency) when the sludge concentration is low, and 1 MHz (second) when the sludge concentration is high.
  • the sludge concentration is measured by using the ultrasonic wave S1 having a frequency of 1).
  • FIG. 3 shows the relationship between the attenuation amount of the ultrasonic wave S1 of 1 MHz and 3 MHz and the sludge concentration.
  • the sludge concentration is attenuated even with 0% water, and the concentration increases when the sludge concentration exceeds a predetermined sludge concentration (for example, 7%). Even so, the attenuation does not change and is saturated.
  • the concentration that shows linearity is less than 5%.
  • the ultrasonic wave S1 is suitable for the measurement in the low concentration region, it cannot measure the high concentration region.
  • the ultrasonic wave S1 of 1 MHz is suitable for measurement in a high concentration region, but cannot measure a low concentration. Therefore, in the ultrasonic densitometer 26 of the present embodiment, the automatic switching transition point P1 is set, and the sludge concentration is measured by switching the frequency of the ultrasonic wave S1 with the set concentration value corresponding to the transition point P1. Specifically, when the sludge concentration decreases and reaches the set concentration value of the automatic switching transition point P1 from the high concentration side, the frequency of the ultrasonic wave S1 is automatically switched from the frequency of 1 MHz to the frequency of 3 MHz.
  • the frequency of the ultrasonic wave S1 is automatically switched from the frequency of 3 MHz to the frequency of 1 MHz.
  • the set concentration value corresponding to the automatic switching transition point P1 is set in a region where the amount of change in ultrasonic attenuation with respect to the sludge concentration has a linear relationship with respect to each of the ultrasonic waves S1 of 3 MHz and 1 MHz.
  • the ultrasonic densitometer 26 is configured to adjust the gain of signal amplification for the ultrasonic wave S1 of 1 MHz based on the sludge concentration measured by the ultrasonic wave S1 of 3 MHz.
  • the ultrasonic densitometer 26 includes a 4ch reception sensor 32 and a reception circuit 34, but adjusts the gain of signal amplification for each 4ch reception signal. In addition, when the signal amplification gain is reduced, the measurement region showing linearity in the relationship between the attenuation and the sludge concentration shifts to the low concentration side, so the set concentration value corresponding to the automatic switching transition point P1 is set to the low concentration. (For example, a density value of 4% to 3%).
  • the controller 36 measures the sludge concentration using 3 MHz ultrasonic waves S1 (step 100). Specifically, the controller 36 outputs a control signal to the ultrasonic oscillator 33 and causes each transmission sensor 31 to output a drive signal of 3 MHz from the ultrasonic oscillator 33. At this time, the ultrasonic wave S1 of 3 MHz is output from the transmission sensor 31 into the sludge W1 of the pipe body 30, and the ultrasonic wave S1 propagated through the sludge W1 is received by the reception sensor 32. Then, the reception signal of the ultrasonic wave S1 is acquired by the reception circuit 34, amplified by the signal amplification circuit 35, and then taken into the controller 36.
  • the controller 36 obtains an ultrasonic attenuation amount based on the intensity of the received signal of the ultrasonic wave S1. And the controller 36 calculates
  • the controller 36 outputs a control signal to the signal amplification circuit 35 based on the sludge concentration measured using the 3 MHz ultrasonic wave S1, and adjusts the gain of signal amplification corresponding to the 1 MHz ultrasonic wave S1 (Ste 110).
  • the signal amplification gain is set to a high value, and when it is less than 3%, the signal amplification gain is set to a low value.
  • the transmission sensor 31 and the reception sensor 32 of each channel have different signal strengths of reception signals obtained by the reception circuit 34 due to element variations. Therefore, in step 110, the gain of each channel is adjusted so as to reduce the element variation.
  • the controller 36 as the set density value changing means sets a set density value corresponding to the automatic switching transition point P1 for changing the frequency of the ultrasonic wave S1, and stores it in the memory 39 (step 120). Specifically, when the sludge concentration is 3% or more, for example, the set concentration value corresponding to the automatic switching transition point P1 is set to 4%, and when it is less than 3%, the automatic switching transition point P1 is set. The corresponding set density value is set to 3%. As described above, in the present embodiment, the set concentration value corresponding to the automatic switching transition point P1 is switched based on the sludge concentration measured by the ultrasonic wave S1 of 3 MHz.
  • the controller 36 determines whether or not the sludge concentration measured in step 100 is equal to or higher than the set concentration value corresponding to the automatic switching transition point P1 (step). 130).
  • the controller 36 outputs a control signal to the ultrasonic oscillator 33 and changes the drive signal output from the ultrasonic oscillator 33 to a signal of 1 MHz (step 140). )
  • the frequency of the drive signal of the ultrasonic oscillator 33 is not changed from 3 MHz, and the processing of FIG.
  • the controller 36 executes the processing of FIG. That is, the controller 36 causes the ultrasonic oscillator 33 to output a drive signal having the frequency set in the processing of FIG. 4, and causes the transmission sensor 31 and the reception sensor 32 to transmit / receive the ultrasonic wave S ⁇ b> 1 having that frequency. And the controller 36 calculates
  • the controller 36 as the concentration determination means determines whether or not the sludge concentration measured in step 200 has reached the set concentration value corresponding to the automatic switching transition point P1 (step 210).
  • the controller 36 as the measurement frequency switching means automatically switches the frequency of the ultrasonic wave S1 to another one and remeasures the sludge concentration ( Step 220).
  • the controller 36 outputs the superfluid output from the transmission sensor 31.
  • the frequency of sound waves (drive signal of the ultrasonic oscillator 33) is switched from 1 MHz to 3 MHz, and the sludge concentration is measured again.
  • the controller 36 outputs the ultrasonic wave S1 output from the transmission sensor 31.
  • the frequency (drive signal of the ultrasonic oscillator 33) is switched from 3 MHz to 1 MHz, and the sludge concentration is measured again. Thereafter, the controller 36 outputs the sludge concentration data remeasured in step 220 to the display device 37, the chemical charging device 24, and the sludge dehydrator 13 (step 230). At this time, the sludge concentration is displayed on the display device 37.
  • the controller 36 determines that the sludge concentration has not reached the set concentration value
  • the controller 36 proceeds to Step 230 without switching the frequency of the ultrasonic wave S1 (the drive signal of the ultrasonic oscillator 33).
  • the controller 36 outputs the sludge concentration data measured in step 200 to the display device 37, the chemical injection device 24 and the sludge dehydrator 13. At this time, the sludge concentration is displayed on the display device 37.
  • the controller 36 determines whether or not the power button is turned off after the sludge concentration data is output (step 240). If the power button is turned off, the process of FIG. 5 is terminated. On the other hand, if the power button is on, the controller 36 returns to the process of step 200 and repeatedly executes the processes of step 200 to step 240.
  • the frequency of the ultrasonic wave S1 used for calculating the sludge concentration is automatically set. Can be switched.
  • the sludge concentration is lower than the set concentration value, the sludge concentration is obtained using the 3 MHz ultrasonic wave S1 suitable for the measurement in the low concentration range.
  • the sludge concentration is higher than the set concentration value, the high concentration is obtained.
  • the sludge concentration is determined using 1 MHz ultrasonic wave S1 suitable for the measurement of the area. In this way, the sludge concentration can be accurately determined from a low concentration to a high concentration.
  • the frequency of the ultrasonic wave S1 used for concentration measurement is switched between 3 MHz as the first frequency and 1 MHz as the second frequency.
  • the frequency of 3 MHz as the first frequency is a frequency (third harmonic) that is three times the frequency (fundamental wave) of 1 MHz as the second frequency.
  • the piezoelectric element constituting the transmission sensor 31 can be vibrated efficiently at each frequency, and the ultrasonic wave S1 of each frequency can be transmitted from the transmission sensor 31 efficiently and reliably.
  • the gain of signal amplification corresponding to the ultrasonic wave S1 of 1 MHz can be optimized based on the sludge concentration calculated using the ultrasonic wave S1 of 3 MHz. . In this way, the concentration range that can be measured using the 1 MHz ultrasonic wave S1 can be expanded.
  • a plurality of pairs of transmission sensors 31 and reception sensors 32 arranged to face the transmission sensors 31 are provided. Therefore, by averaging the sludge concentrations measured by the transmission sensor 31 and the reception sensor 32, the measurement error can be suppressed low. In addition, since the gain of signal amplification is adjusted for each reception sensor 32, variations in element characteristics in the sensors 31 and 32 can be corrected, and measurement accuracy can be improved.
  • the frequency of the ultrasonic wave S1 is switched from 3 MHz to 1 MHz after adjusting the gain of signal amplification corresponding to the ultrasonic wave S1 of 1 MHz, so the ultrasonic wave S1 of 1 MHz. Can be used to accurately measure the sludge concentration.
  • the signal amplification circuit 35 adjusts the gain of signal amplification to be low, the set density value is changed to the low density side. As a result, the concentration range that can be measured using the ultrasonic wave S1 of 1 MHz can be expanded.
  • the sludge concentration of the sludge W1 discharged from the final sedimentation tank 5 of the sewer facility is measured by the ultrasonic densitometer 26, and the digestion tank 12 is supplied according to the sludge concentration. It is possible to optimally adjust the amount of medicine to be introduced. If it does in this way, a chemical
  • the concentration of sludge discharged from the final sedimentation tank 5 is usually about 3% to 11%.
  • the sludge concentration can be accurately measured by appropriately switching the frequency of the ultrasonic wave S1 in the ultrasonic densitometer 26. Then, by introducing an optimal amount of medicine into the digestion tank 12 according to the sludge concentration, the sludge treatment can be performed efficiently and reliably.
  • the sludge treatment system 1 is configured in this way, the digester tank 12 having a relatively small volume can be used, and the equipment cost can be reduced.
  • the operating rate of the sludge dehydrator 13 is adjusted based on the sludge concentration measured by the ultrasonic densitometer 26. In this case, since the sludge dehydrator 13 is operated in an optimum state, the power consumption can be kept low, and the running cost of the sludge treatment system 1 can be reduced.
  • the sludge concentration is displayed on the display device 37, but the present invention is not limited to this.
  • a warning message or the like may be displayed on the display device 37 together with the sludge concentration.
  • the sludge concentration is displayed and a graph having line segments L1, L2, L3 indicating the relationship between the sludge concentration and the attenuation amount of the ultrasonic wave S1 as shown in FIG. It may be displayed every time.
  • a straight line indicating the set concentration value corresponding to the frequency automatic switching transition point P1 in the graph having line segments L1, L2, and L3 indicating the relationship between the sludge concentration and the attenuation amount of the ultrasonic wave S1. L4 may be displayed.
  • an alarm device 41 is provided separately, and when the sludge concentration becomes an abnormal value based on the sludge concentration data output from the ultrasonic densitometer 26, You may comprise so that it may notify that it is system abnormality using a warning buzzer, a warning lamp, etc.
  • the set concentration value corresponding to the automatic switching transition point P1 is set according to the sludge concentration measured by the ultrasonic S1 of 3 MHz as the initialization process. It is not limited. In general, in the sludge treatment system 1 in the sewage treatment plant, the treatment capacity of the aeration tank 4 and the like varies depending on the season, and the concentration of the sludge W1 discharged from the final sedimentation tank 5 also changes. Specifically, in a relatively warm season with a lot of rainfall, the microorganisms in the aeration tank 4 work actively, so that the sludge concentration tends to be low.
  • the ultrasonic concentration meter 26 may be configured to measure the temperature of the sludge W1 and change the set concentration value corresponding to the automatic switching transition point P1 based on the temperature.
  • a thermometer may be provided separately from the ultrasonic densitometer 26, or a thermometer function (temperature measuring means) may be added to the ultrasonic densitometer 26.
  • the ultrasonic densitometer 26 is provided with a timer for measuring the propagation time of the ultrasonic wave S1, and the propagation time of the ultrasonic wave S1 measured by the timer is taken into the controller 36.
  • the controller 36 as a temperature measurement means is comprised so that the temperature of the sludge W1 may be measured based on the propagation time.
  • the sludge concentration changes abruptly at the turn of the season. For this reason, even if the set concentration value corresponding to the automatic switching transition point P1 is changed based on the rate of change in attenuation at a specific sludge concentration (for example, a concentration of 5%) at the time of measurement using a frequency of 1 MHz. Good. Further, even if the set concentration value corresponding to the automatic switching transition point P1 is changed based on the rate of change of attenuation at a specific sludge concentration (for example, 2% concentration) at the time of measurement using a frequency of 3 MHz. Good.
  • a specific sludge concentration for example, a concentration of 5%
  • data of date information and weather information is input to the ultrasonic densitometer 26 from a control device (not shown) that supervises the sludge treatment system 1 and corresponds to the automatic switching transition point P1 according to the data.
  • the ultrasonic densitometer 26 may be configured to change the set density value.
  • the same set concentration value is used when the frequency of the ultrasonic wave S1 is switched from 1 MHz to 3 MHz when the sludge concentration is decreased and when the frequency is switched from 3 MHz to 1 MHz when the sludge concentration is increased.
  • the present invention is not limited to this. You may comprise so that the frequency of the ultrasonic wave S1 may be switched using a different setting density value by the case where it switches from 1 MHz to 3 MHz, and the case where it switches from 3 MHz to 1 MHz.
  • the signal amplification gain for the 1 MHz ultrasonic wave S1 is automatically adjusted based on the sludge concentration measured by the 3 MHz ultrasonic wave S1. It is not limited to. On the contrary, the ultrasonic densitometer 26 may be configured to automatically adjust the gain of signal amplification for the ultrasonic wave S1 of 3 MHz based on the sludge concentration measured by the ultrasonic wave S1 of 1 MHz.
  • the 4ch transmission sensor 31 and the reception sensor 32 are provided, but the number of channels of the transmission sensor 31 and the reception sensor 32 may be changed as appropriate.
  • the ultrasonic densitometer 26 is configured to obtain the sludge concentration using the ultrasonic waves S1 of 1 MHz and 3 MHz. However, the sludge concentration may be obtained using the ultrasonic waves S1 having other different frequencies. However, it is preferable that the frequency is switched between the fundamental wave and its third harmonic as in the above embodiment. If comprised in this way, the ultrasonic wave S1 from which the frequency differs from one transmission sensor 31 can be output efficiently.
  • the transmission sensor 31 and the reception sensor 32 are provided at positions facing each other across the flow path of the tube main body 30, and the ultrasonic concentration meter 26 is super perpendicular to the direction in which the sludge W1 flows.
  • the sound wave S1 is transmitted and received
  • the transmission sensor 31 and the reception sensor 32 may be provided so as to transmit and receive the ultrasonic wave S1 in parallel with the flow direction of the sludge W1.
  • an ultrasonic densitometer 26 is provided on the downstream side of the branch part that returns the sludge W1 to the aeration tank 4.
  • the ultrasonic densitometer 26 may be provided in a pipe on the upstream side of the branch portion or a pipe on the aeration tank 4 side.
  • the adjustment of the input amount of the chemical in the digestion tank 12 is performed based on the sludge concentration measured by the two ultrasonic densitometers 22 and 26, it is limited to this. It is not a thing. You may comprise so that adjustment of the injection
  • the amount of chemical to be fed into the digester 12 is adjusted based on the sludge concentration measured by the ultrasonic densitometers 22 and 26, or the operating rate of the sludge dehydrator 13
  • it may be configured to adjust processing conditions in processing apparatuses other than these. Specifically, based on the sludge concentration measured by the ultrasonic densitometer 26, for example, the thermal power adjustment in the sludge incinerator 14 or the chemical input amount in the powder dephosphorization apparatus 15 may be adjusted. Good.
  • Claim 2 or 3 further comprising a signal amplifying means capable of amplifying and outputting a received signal of the ultrasonic receiving means and adjusting a gain of the signal amplification, wherein the signal amplifying means includes the second signal amplifying means.
  • the apparatus includes temperature measuring means for measuring the temperature of the sludge to be measured, and the set concentration value changing means corresponds to the automatic switching transition point based on the measurement result of the temperature measuring means.
  • the temperature measuring means measures the temperature based on the propagation time of the ultrasonic wave propagating through the measured sludge. Densitometer.
  • the set concentration value changing means is the rate of change of the attenuation amount at a specific sludge concentration at the first frequency, and the specific sludge concentration at the second frequency.
  • An ultrasonic densitometer for sludge concentration measurement wherein a set concentration value corresponding to the automatic switching transition point is changed based on a change rate of the attenuation amount.
  • a graph having a line segment indicating the relationship between the sludge concentration and the ultrasonic attenuation is displayed for each ultrasonic frequency.
  • An ultrasonic densitometer for measuring the concentration of sludge comprising a display device for displaying on the screen.
  • an ultrasonic densitometer for sludge concentration measurement comprising: a display device for displaying a straight line indicating a set concentration value corresponding to the automatic switching transition point of the frequency in the graph.
  • a water treatment process is performed by circulating sewage in the order of a sand basin, an initial sedimentation tank, an aeration tank or a closed tank, and a final sedimentation tank, and a sludge treatment process is performed using a treatment apparatus group including a plurality of kinds of treatment apparatuses.
  • the ultrasonic treatment according to any one of claims 1 to 8, wherein the ultrasonic treatment system is a sludge treatment system for a sewerage facility that is provided in the middle of a pipe that supplies the sludge discharged from the final sedimentation tank to the treatment device group.
  • a sludge treatment system comprising: a densitometer; and an adjusting unit that adjusts a treatment condition in the treatment device based on the sludge concentration measured by the ultrasonic densitometer.

Abstract

[Problem] To provide an ultrasonic concentration meter in which the sludge concentration can be accurately measured by switching the frequency of ultrasound according to sludge concentration. [Solution] A controller (36) determines whether or not the sludge concentration has reached a preset concentration value corresponding to the change point in which the frequency is automatically switched. The controller (36), upon determining that the sludge concentration has decreased and reached the preset concentration value from the high-concentration side, automatically switches the frequency of ultrasound (S1) emitted by a transmission sensor (31) from 1MHz to 3MHz. The controller (36), upon determining that the sludge concentration has increased and reached the preset concentration value from the low-concentration side, automatically switches the frequency of ultrasound (S1) emitted by the transmission sensor (31) from 3MHz to 1MHz.

Description

汚泥濃度測定用の超音波濃度計、及び汚泥処理システムUltrasonic densitometer for measuring sludge concentration and sludge treatment system
　本発明は、汚泥を伝搬する超音波の減衰量に基づいて汚泥濃度を測定する汚泥濃度測定用の超音波濃度計、及びその超音波濃度計を備えた汚泥処理システムに関するものである。 The present invention relates to an ultrasonic densitometer for measuring the concentration of sludge based on the attenuation amount of ultrasonic waves propagating through the sludge, and a sludge treatment system including the ultrasonic densitometer.
　従来、超音波を利用して液体の濃度を測定する超音波濃度計が実用化されている。超音波濃度計は、電磁波やレーザーを用いた濃度計と比較して、コストを低く抑えることができる。また、超音波濃度計は、液体に含まれる浮遊物の濃度を測定することができ、さらに液体の透視度や液色にかかわらず濃度を測定することができるといったメリットがある。このようなことから、超音波濃度計は、下水道施設における汚泥濃度を測定するために用いられている（例えば、特許文献１等参照）。 Conventionally, ultrasonic densitometers that measure the concentration of liquid using ultrasonic waves have been put into practical use. The ultrasonic densitometer can keep costs low as compared with a densitometer using an electromagnetic wave or a laser. In addition, the ultrasonic densitometer can measure the concentration of suspended matter contained in the liquid, and further has an advantage that the concentration can be measured regardless of the transparency and liquid color of the liquid. For this reason, ultrasonic densitometers are used to measure the sludge concentration in sewer facilities (see, for example, Patent Document 1).
　特許文献１に開示されている汚泥濃度測定装置では、２種類の周波数（例えば、１ＭＨｚと３ＭＨｚ）の超音波を被測定汚泥に伝搬させている。そして、各周波数の超音波の減衰量に基づいて、被測定汚泥に含まれる気泡による減衰量を補正して被測定汚泥の濃度を算出している。 In the sludge concentration measuring apparatus disclosed in Patent Document 1, ultrasonic waves of two types (for example, 1 MHz and 3 MHz) are propagated to the measured sludge. And based on the attenuation amount of the ultrasonic wave of each frequency, the attenuation amount by the bubble contained in the measurement sludge is corrected, and the concentration of the measurement sludge is calculated.
特開２００３−２０２３２７号公報JP 2003-202327 A
　ところで、下水道施設が正常に運転される場合、汚泥濃度は３％程度から１１％程度の濃度となるが、下水道施設の処理が異常となる場合、汚泥濃度が例えば３％以下となることがある。汚泥濃度が３％以下となると、１ＭＨｚの超音波では減衰が殆ど起こらなくなり、特許文献１の汚泥濃度測定装置では、正確な汚泥濃度が測定できなくなるといった問題が生じてしまう。また、下水道施設の異常時には、汚泥濃度が高くなる場合も考えられる。この場合、３ＭＨｚの超音波は汚泥中の異物で確実に反射するようになり、汚泥濃度に応じた減衰量が飽和してしまうため、汚泥濃度が正確に測定できなくなる。 By the way, when the sewerage facility is operated normally, the sludge concentration is about 3% to about 11%, but when the treatment of the sewerage facility becomes abnormal, the sludge concentration may be, for example, 3% or less. . When the sludge concentration is 3% or less, the 1 MHz ultrasonic wave hardly attenuates, and the sludge concentration measuring device of Patent Document 1 has a problem that the accurate sludge concentration cannot be measured. In addition, when the sewerage facility is abnormal, the sludge concentration may increase. In this case, the ultrasonic wave of 3 MHz is surely reflected by the foreign matter in the sludge, and the attenuation corresponding to the sludge concentration is saturated, so that the sludge concentration cannot be measured accurately.
　下水道施設における汚泥の処理能力に余裕がある場合、汚泥濃度に異常が生じても各処理槽において汚泥処理を問題なく行うことができるため、正確な汚泥濃度管理を行う必要がなかった。これに対して、近年の下水道施設では、処理能力の最適化を図ることで処理設備の省スペース化が図られている。このような処理設備では、各処理槽での汚泥濃度管理を正確に行って汚泥処理を効率よく行うことが求められている。 If there is a margin for sludge treatment capacity in the sewerage facility, sludge treatment can be performed in each treatment tank without any problems even if an abnormality occurs in the sludge concentration, so there was no need to perform accurate sludge concentration management. On the other hand, in recent sewer facilities, the processing capacity is reduced by optimizing the processing capacity. Such a treatment facility is required to efficiently perform sludge treatment by accurately performing sludge concentration management in each treatment tank.
　本発明は上記の課題に鑑みてなされたものであり、その目的は、汚泥濃度を正確に測定することができる汚泥濃度測定用の超音波濃度計を提供することにある。また別の目的は、汚泥濃度を正確に測定して汚泥処理を効率よく行うことができる汚泥処理システムを提供することにある。 The present invention has been made in view of the above problems, and an object of the present invention is to provide an ultrasonic densitometer for sludge concentration measurement that can accurately measure the sludge concentration. Another object is to provide a sludge treatment system capable of measuring sludge concentration accurately and performing sludge treatment efficiently.
　上記課題を解決するために、請求項１に記載の発明は、被測定汚泥中に周波数の異なる超音波を発信可能な超音波送信手段と、前記被測定汚泥中を伝搬した前記超音波を受信する超音波受信手段とを備え、前記超音波の受信信号の強度から超音波減衰量を求め、前記超音波減衰量から前記被測定汚泥の汚泥濃度を演算する超音波濃度計であって、前記汚泥濃度が前記周波数の自動切換変移点に対応した設定濃度値に到達したか否かを判定する濃度判定手段と、前記設定濃度値に到達したと前記濃度判定手段が判断したときに、前記超音波送信手段が発信する前記超音波の周波数を別のものに自動的に切り換える測定用周波数切換手段とを備えたことを特徴とする汚泥濃度測定用の超音波濃度計をその要旨とする。 In order to solve the above problems, the invention according to claim 1 is directed to an ultrasonic transmission means capable of transmitting ultrasonic waves having different frequencies in the measured sludge, and receiving the ultrasonic waves propagated in the measured sludge. And an ultrasonic densitometer that calculates the amount of ultrasonic attenuation from the intensity of the received signal of the ultrasonic wave, and calculates the sludge concentration of the sludge to be measured from the ultrasonic attenuation amount, When the concentration determination means determines whether the sludge concentration has reached a set concentration value corresponding to the automatic switching transition point of the frequency, and when the concentration determination means determines that the set concentration value has been reached, The gist thereof is an ultrasonic densitometer for measuring the concentration of sludge, characterized by comprising a measuring frequency switching means for automatically switching the frequency of the ultrasonic wave transmitted by the sound wave transmitting means to another one.
　請求項１に記載の発明によると、汚泥濃度が自動切換変移点に対応した設定濃度値に到達したか否かが判定され、設定濃度値に到達したと判定されたときに、汚泥濃度の演算に用いる超音波の周波数が自動的に切り換えられる。このようにすると、汚泥濃度が変化する場合、その汚泥濃度に合わせた最適な周波数の超音波を用いて、汚泥濃度を正確に求めることができる。具体的には、汚泥濃度が低い場合、超音波の周波数が低すぎると、超音波が汚泥中の異物に反射しなくなり、汚泥濃度に応じた減衰が起こり難くなる。一方、汚泥濃度が高い場合、超音波の周波数が高すぎると、超音波が汚泥中の異物で確実に反射するようになり、汚泥濃度に応じた減衰量が飽和してしまう。従って、汚泥濃度が設定濃度値よりも低い場合には、高い周波数の超音波を用いて汚泥濃度を求める。一方、汚泥濃度が設定濃度値よりも高くなった場合には、低い周波数の超音波に切り換え、その低い周波数の超音波を用いて汚泥濃度を求める。このように超音波濃度計を構成すると、汚泥濃度を低濃度から高濃度まで正確に求めることができる。 According to the first aspect of the present invention, it is determined whether or not the sludge concentration has reached the set concentration value corresponding to the automatic switching transition point. When it is determined that the sludge concentration has reached the set concentration value, the sludge concentration is calculated. The frequency of the ultrasonic wave used for is automatically switched. In this way, when the sludge concentration changes, the sludge concentration can be accurately obtained using the ultrasonic wave having the optimum frequency according to the sludge concentration. Specifically, when the sludge concentration is low, if the frequency of the ultrasonic wave is too low, the ultrasonic wave is not reflected on the foreign matter in the sludge, and attenuation according to the sludge concentration is difficult to occur. On the other hand, when the sludge concentration is high, if the frequency of the ultrasonic wave is too high, the ultrasonic wave is surely reflected by the foreign matter in the sludge, and the attenuation corresponding to the sludge concentration is saturated. Accordingly, when the sludge concentration is lower than the set concentration value, the sludge concentration is obtained using high frequency ultrasonic waves. On the other hand, when the sludge concentration becomes higher than the set concentration value, switching to a low frequency ultrasonic wave is performed, and the sludge concentration is obtained using the low frequency ultrasonic wave. If the ultrasonic densitometer is configured in this manner, the sludge concentration can be accurately obtained from a low concentration to a high concentration.
　請求項２に記載の発明は、請求項１において、前記測定用周波数切換手段は、低濃度域の測定に適した第１の周波数と、前記第１の周波数とは異なるものであって高濃度域の測定に適した第２の周波数との間で前記超音波の周波数の切換を行うとともに、前記汚泥濃度が減少して高濃度側から前記設定濃度値に到達したと前記濃度判定手段が判断したときに、前記超音波の周波数を、前記第２の周波数から前記第１の周波数に自動的に切り換える一方、前記汚泥濃度が増加して低濃度側から前記設定濃度値に到達したと前記濃度判定手段が判断したときに、前記超音波の周波数を、前記第１の周波数から前記第２の周波数に自動的に切り換えることをその要旨とする。 A second aspect of the present invention is the method according to the first aspect, wherein the measurement frequency switching means is different from the first frequency suitable for measurement in a low concentration region and the first frequency, and has a high concentration. The ultrasonic wave frequency is switched between the second frequency suitable for the measurement of the area and the concentration determination means determines that the sludge concentration decreases and reaches the set concentration value from the high concentration side. When the frequency of the ultrasonic wave is automatically switched from the second frequency to the first frequency, the concentration increases when the sludge concentration increases and reaches the set concentration value from the low concentration side. The gist of the invention is to automatically switch the frequency of the ultrasonic wave from the first frequency to the second frequency when the determination means determines.
　請求項２に記載の発明によると、汚泥濃度が設定濃度値よりも低い場合、低濃度域の測定に適した第１の周波数の超音波を用いて汚泥濃度が求められ、汚泥濃度が設定濃度値よりも高い場合には、高濃度域の測定に適した第２の周波数の超音波を用いて汚泥濃度が求められる。このように超音波濃度計を構成すると、汚泥濃度を低濃度から高濃度まで正確に求めることができる。 According to the invention described in claim 2, when the sludge concentration is lower than the set concentration value, the sludge concentration is obtained using the ultrasonic wave of the first frequency suitable for the measurement in the low concentration range, and the sludge concentration is set to the set concentration. When the value is higher than the value, the sludge concentration is obtained using ultrasonic waves of the second frequency suitable for measurement in the high concentration range. If the ultrasonic densitometer is configured in this manner, the sludge concentration can be accurately obtained from a low concentration to a high concentration.
　請求項３に記載の発明は、請求項２において、前記第１の周波数は、前記第２の周波数の３倍の周波数であることをその要旨とする。 The gist of the invention described in claim 3 is that, in claim 2, the first frequency is three times the second frequency.
　請求項３に記載の発明によれば、第２の周波数の超音波を基本波とする場合、第１の周波数の超音波はその基本波の第３高調波となる。この場合、超音波送信手段を構成する圧電素子を各周波数で効率よく振動させることができ、超音波送信手段から各周波数の超音波を効率よく確実に発信させることができる。 According to the invention described in claim 3, when the ultrasonic wave of the second frequency is used as the fundamental wave, the ultrasonic wave of the first frequency becomes the third harmonic of the fundamental wave. In this case, the piezoelectric elements constituting the ultrasonic transmission means can be vibrated efficiently at each frequency, and ultrasonic waves of each frequency can be efficiently and reliably transmitted from the ultrasonic transmission means.
　請求項４に記載の発明は、請求項２または３において、前記超音波受信手段の受信信号を増幅して出力するとともに、信号増幅のゲインを調整可能な信号増幅手段をさらに備え、前記信号増幅手段は、前記第１の周波数の超音波を用いて演算した前記汚泥濃度の結果に基づき、前記第２の周波数に対応する前記信号増幅のゲインを自動的に調整することをその要旨とする。 According to a fourth aspect of the present invention, in the second or third aspect, the signal amplification unit further includes a signal amplification unit capable of amplifying and outputting the reception signal of the ultrasonic reception unit and adjusting a gain of the signal amplification. The gist of the means is to automatically adjust the gain of the signal amplification corresponding to the second frequency based on the result of the sludge concentration calculated using the ultrasonic wave of the first frequency.
　請求項４に記載の発明によると、第１の周波数の超音波を用いて演算した汚泥濃度に基づいて、第２の周波数に対応する信号増幅のゲインを最適化することができる。このようにすると、第２の周波数の超音波を用いて測定することが可能な濃度範囲を拡げることができる。 According to the fourth aspect of the invention, the gain of signal amplification corresponding to the second frequency can be optimized based on the sludge concentration calculated using the ultrasonic wave of the first frequency. In this way, the concentration range that can be measured using the ultrasonic waves of the second frequency can be expanded.
　請求項５に記載の発明は、請求項４において、前記超音波送信手段及びそれに対向して配置される前記超音波受信手段は複数対設けられるとともに、前記信号増幅手段は、前記超音波受信手段毎に信号増幅のゲインを調整することをその要旨とする。 According to a fifth aspect of the present invention, in the fourth aspect, a plurality of pairs of the ultrasonic transmission means and the ultrasonic reception means arranged opposite to the ultrasonic transmission means are provided, and the signal amplification means includes the ultrasonic reception means. The gist is to adjust the gain of signal amplification every time.
　請求項５に記載の発明によると、超音波送信手段及びそれに対向して配置される超音波受信手段が複数対設けられるので、それぞれの超音波送信手段及び超音波受信手段で測定した汚泥濃度を平均化することで、測定誤差を低く抑えることができる。また、超音波受信手段毎に信号増幅のゲインが調整されるので、超音波送信手段及び超音波受信手段における素子特性のバラツキを補正することができ、測定精度を高めることができる。 According to the invention described in claim 5, since a plurality of pairs of ultrasonic transmission means and ultrasonic reception means arranged opposite to each other are provided, the sludge concentration measured by each ultrasonic transmission means and ultrasonic reception means is determined. By averaging, the measurement error can be kept low. Further, since the gain of signal amplification is adjusted for each ultrasonic receiving means, variations in element characteristics between the ultrasonic transmitting means and the ultrasonic receiving means can be corrected, and the measurement accuracy can be improved.
　請求項６に記載の発明は、請求項４または５において、前記測定用周波数切換手段は、前記信号増幅手段による前記ゲインの調整後に前記超音波の周波数の切換を行うことをその要旨とする。 The gist of the invention described in claim 6 is that, in claim 4 or 5, the measurement frequency switching means switches the frequency of the ultrasonic wave after the gain adjustment by the signal amplifying means.
　請求項６に記載の発明によれば、第２の周波数に対応する信号増幅のゲインの調整後に、超音波の周波数が第１の周波数から第２の周波数に切り換えられるので、第２の周波数の超音波を用いて汚泥濃度を正確に測定することができる。 According to the invention described in claim 6, since the frequency of the ultrasonic wave is switched from the first frequency to the second frequency after the gain of the signal amplification corresponding to the second frequency is adjusted, The sludge concentration can be accurately measured using ultrasonic waves.
　請求項７に記載の発明は、請求項１乃至６のいずれか１項において、前記自動切換変移点に対応した設定濃度値を変更する設定濃度値変更手段をさらに備えたことをその要旨とする。 The gist of the invention described in claim 7 is that, in any one of claims 1 to 6, further comprising a set density value changing means for changing a set density value corresponding to the automatic switching transition point. .
　請求項７に記載の発明によると、設定濃度値変更手段によって自動切換変移点に対応した設定濃度値が変更される。この場合、超音波濃度計の使用環境（被測定汚泥の温度や濃度等）に応じて自動切換変移点を変更することができ、使用環境に応じた適切な設定濃度値で超音波の周波数を切り換えることができる。 According to the invention described in claim 7, the set density value corresponding to the automatic switching transition point is changed by the set density value changing means. In this case, the automatic switching transition point can be changed according to the environment in which the ultrasonic densitometer is used (temperature, concentration, etc. of the sludge to be measured), and the ultrasonic frequency is set at an appropriate set concentration value according to the environment. Can be switched.
　請求項８に記載の発明は、請求項７において、前記設定濃度値変更手段は、前記信号増幅手段によって前記ゲインが低くなるように調整されたときに、前記設定濃度値を低濃度側に変更することをその要旨とする。 The invention according to claim 8 is the invention according to claim 7, wherein the set density value changing means changes the set density value to a low density side when the gain is adjusted to be low by the signal amplifying means. The gist is to do.
　請求項８に記載の発明によると、第２の周波数に対応する信号増幅のゲインに応じて設定濃度値を適切に変更することができ、第２の周波数の超音波を用いて測定することが可能な濃度範囲を拡げることができる。 According to the eighth aspect of the present invention, the set concentration value can be appropriately changed according to the gain of signal amplification corresponding to the second frequency, and measurement can be performed using the ultrasonic wave of the second frequency. The possible concentration range can be expanded.
　請求項９に記載の発明は、沈砂池と、最初沈殿槽と、曝気槽または密閉槽と、最終沈殿槽とを用いて水処理工程を行うとともに、薬剤処理槽を含む複数種の処理装置からなる処理装置群を用いて汚泥処理工程を行う下水道施設の汚泥処理システムであって、前記最終沈殿槽から排出された汚泥を前記処理装置群に供給する配管の途中に設けられた請求項１乃至８のいずれか１項に記載の超音波濃度計と、前記超音波濃度計が測定した前記汚泥濃度に基づいて、前記薬剤処理槽に投入する薬剤の投入量を調整する薬剤投入量調整手段とを備えたことを特徴とする汚泥処理システムをその要旨とする。 The invention according to claim 9 performs a water treatment process using a sand basin, an initial settling tank, an aeration tank or a sealed tank, and a final settling tank, and a plurality of types of processing apparatuses including a chemical treatment tank. A sludge treatment system of a sewerage facility that performs a sludge treatment process using a treatment device group, wherein the sludge discharged from the final sedimentation tank is provided in the middle of a pipe that supplies the treatment device group. The ultrasonic concentration meter according to any one of claims 8 and 8, a chemical input amount adjusting means for adjusting an input amount of the chemical to be input to the chemical treatment tank based on the sludge concentration measured by the ultrasonic concentration meter; A sludge treatment system characterized by comprising
　請求項９に記載の発明によると、下水道施設の最終沈殿槽から排出された汚泥の汚泥濃度が超音波濃度計によって測定され、その汚泥濃度に応じて薬剤処理槽に投入する薬剤の投入量を最適に調整することができる。このようにすると、薬剤が無駄に使用されることがなく、汚泥処理システムのランニングコストを低く抑えることができる。また、汚泥処理システムでは、比較的容積の小さな薬剤処理槽を用いることが可能となり、設備コストを低く抑えることができる。 According to invention of Claim 9, the sludge density | concentration of the sludge discharged | emitted from the final sedimentation tank of a sewer facility is measured with an ultrasonic densitometer, and the input amount of the chemical | drug | medicine thrown into a chemical | medical agent processing tank according to the sludge density | concentration is used. It can be adjusted optimally. If it does in this way, a chemical | medical agent will not be used wastefully and the running cost of a sludge processing system can be suppressed low. Further, in the sludge treatment system, it is possible to use a chemical treatment tank having a relatively small volume, and the equipment cost can be kept low.
　請求項１０に記載の発明は、請求項９において、前記処理装置群には汚泥脱水機が含まれ、前記超音波濃度計が測定した前記汚泥濃度に基づいて、前記汚泥脱水機の稼働率を調整することをその要旨とする。 The invention according to claim 10 is the invention according to claim 9, wherein the treatment device group includes a sludge dehydrator, and the operating rate of the sludge dehydrator is determined based on the sludge concentration measured by the ultrasonic densitometer. The gist is to adjust.
　請求項１０に記載の発明によると、超音波濃度計が測定した汚泥濃度に基づいて、汚泥脱水機の稼働率が調整される。この場合、汚泥脱水機が最適な状態で稼動されるため、その消費電力を低く抑えることができ、汚泥処理システムのランニングコストを低減することができる。 According to the invention described in claim 10, the operating rate of the sludge dewatering machine is adjusted based on the sludge concentration measured by the ultrasonic densitometer. In this case, since the sludge dewatering machine is operated in an optimum state, the power consumption can be kept low, and the running cost of the sludge treatment system can be reduced.
　以上詳述したように、請求項１~８に記載の発明によると、汚泥濃度に応じて超音波の周波数を自動的に切り換えることにより、汚泥濃度を正確に測定できる超音波濃度計を提供することができる。また、請求項９または１０に記載の発明によると、汚泥濃度を正確に測定して汚泥処理を効率よく行うことができる汚泥処理システムを提供することができる。 As described in detail above, according to the first to eighth aspects of the invention, an ultrasonic densitometer that can accurately measure the sludge concentration by automatically switching the frequency of the ultrasonic wave according to the sludge concentration is provided. be able to. Moreover, according to invention of Claim 9 or 10, the sludge processing system which can measure sludge density | concentration correctly and can perform sludge processing efficiently can be provided.
一実施の形態の汚泥処理システムを示す概略構成図。The schematic block diagram which shows the sludge processing system of one embodiment. 超音波濃度計を示す概略構成図。The schematic block diagram which shows an ultrasonic densitometer. 超音波減衰量と汚泥濃度との関係を示すグラフ。The graph which shows the relationship between ultrasonic attenuation and sludge density | concentration. 汚泥濃度測定処理を示すフローチャート。The flowchart which shows a sludge density | concentration measurement process. 汚泥濃度測定処理を示すフローチャート。The flowchart which shows a sludge density | concentration measurement process. 別の実施の形態の汚泥処理システムを示す概略構成図。The schematic block diagram which shows the sludge processing system of another embodiment.
　以下、本発明を下水道施設の汚泥処理システムに具体化した一実施の形態を図面に基づき詳細に説明する。 Hereinafter, an embodiment in which the present invention is embodied in a sludge treatment system of a sewer facility will be described in detail with reference to the drawings.
　図１に示されるように、本実施の形態の汚泥処理システム１は、水処理工程を行うための設備として、沈砂池２、最初沈殿槽３、曝気槽４、最終沈殿槽５等を備える。さらに、汚泥処理システム１は、汚泥処理工程を行うための処理装置群として、浮上濃縮槽１１、消化槽１２、汚泥脱水機１３、汚泥焼却炉１４、造粉脱りん装置１５等の処理装置を備えている。 As shown in FIG. 1, the sludge treatment system 1 of the present embodiment includes a sand basin 2, an initial sedimentation tank 3, an aeration tank 4, a final sedimentation tank 5, and the like as equipment for performing a water treatment process. Furthermore, the sludge treatment system 1 includes treatment devices such as a flotation concentration tank 11, a digestion tank 12, a sludge dehydrator 13, a sludge incinerator 14, and a powder dephosphorization device 15 as treatment device groups for performing a sludge treatment process. I have.
　沈砂池２は、各家庭や事業所などから排出される下水を緩やかに流し、ゴミや土砂などを沈めて除去するための人工池である。最初沈殿槽３には沈砂池２から排出される下水が流され、浮いている小さなゴミが取り除かれるとともに、最初沈殿槽３の底部に沈殿した汚泥Ｗ１（生汚泥）が配管２１を通して消化槽１２に送られる。また、最初沈殿槽３と消化槽１２とを繋ぐ配管２１の途中に超音波濃度計２２が設けられており、超音波濃度計２２によって、消化槽１２に送られる汚泥Ｗ１の濃度が測定される。 Sedimentation basin 2 is an artificial pond that gently drains sewage discharged from households and business establishments to sink and remove trash and earth and sand. The sewage discharged from the settling basin 2 is poured into the first settling tank 3 to remove the small dust that floats, and the sludge W1 (raw sludge) that has settled at the bottom of the first settling tank 3 passes through the pipe 21 to the digestion tank 12. Sent to. In addition, an ultrasonic densitometer 22 is provided in the middle of a pipe 21 that first connects the sedimentation tank 3 and the digestion tank 12, and the concentration of the sludge W <b> 1 sent to the digestion tank 12 is measured by the ultrasonic densitometer 22. .
　曝気槽４において、下水を浄化するための微生物を含んだ活性汚泥が、圧搾空気によって下水と混ぜられる。そして、微生物の働きによって下水中の有機物が分解される。なお、曝気槽４を用いて好気性微生物で処理を行う方法に代えて、密閉槽を用いて嫌気性微生物で処理を行う方法を採用してもよい。 In the aeration tank 4, activated sludge containing microorganisms for purifying sewage is mixed with sewage by compressed air. And the organic matter in sewage is decomposed by the action of microorganisms. In addition, it may replace with the method of processing with an aerobic microorganism using the aeration tank 4, and may employ | adopt the method of processing with an anaerobic microorganism using a sealed tank.
　最終沈殿槽５では、下水を浄化した活性汚泥を沈め、上澄みを処理水Ｗ２として取り出す。またこの処理水Ｗ２は、砂の層を通すことで濾過して浮遊物を取り除いた後に、河川に放流される。そして、最終沈殿槽５から排出される沈殿汚泥Ｗ１の一部が活性汚泥として曝気槽４に返送されるとともに、残りの汚泥Ｗ１は浮上濃縮槽１１に送られる。 In the final sedimentation tank 5, the activated sludge purified from the sewage is submerged, and the supernatant is taken out as treated water W2. Further, the treated water W2 is filtered by passing through a layer of sand to remove suspended matters, and then discharged into the river. A part of the precipitated sludge W1 discharged from the final settling tank 5 is returned to the aeration tank 4 as activated sludge, and the remaining sludge W1 is sent to the floating concentration tank 11.
　浮上濃縮槽１１では、最終沈殿槽５から供給された汚泥Ｗ１を加圧浮上させることで濃縮し、その濃縮した汚泥Ｗ１を薬剤処理槽としての消化槽１２に送る。消化槽１２は、汚泥Ｗ１中の有機物を嫌気性消化によって分解する。このとき、有機物の分解によってメタンガスが発生し、そのメタンガスはガスタンク（図示略）に回収されて汚泥焼却炉１４等の燃料として利用される。 In the levitation concentration tank 11, the sludge W1 supplied from the final sedimentation tank 5 is concentrated by raising the pressure, and the concentrated sludge W1 is sent to a digestion tank 12 as a chemical treatment tank. The digestion tank 12 decomposes organic substances in the sludge W1 by anaerobic digestion. At this time, methane gas is generated by the decomposition of the organic matter, and the methane gas is collected in a gas tank (not shown) and used as fuel for the sludge incinerator 14 and the like.
　消化槽１２で処理された汚泥Ｗ１は水分を多く含んでいるため、その汚泥Ｗ１が汚泥脱水機１３に送られて脱水される。この結果、水分を少なくした土の状態とする。そして、土の状態のものを汚泥焼却炉１４で焼却処理した後、セメントや肥料の原料として外部に搬出する。 Since the sludge W1 treated in the digestion tank 12 contains a lot of moisture, the sludge W1 is sent to the sludge dehydrator 13 and dehydrated. As a result, the soil is reduced in moisture. And after incinerating the thing of a soil state with the sludge incinerator 14, it carries out outside as a raw material of cement or a fertilizer.
　また、汚泥脱水機１３から排出される排水を造粉脱りん装置１５に送る。そして、造粉脱りん装置１５において、その排水中に含まれているりんを、りん酸マグネシウムアンモニウムの結晶として回収する。この回収したりん酸マグネシウムアンモニウムは、肥料の原料として業者に売却される。 Also, the waste water discharged from the sludge dehydrator 13 is sent to the powder dephosphorization device 15. And in the powder dephosphorization apparatus 15, the phosphorus contained in the waste water is collect | recovered as a crystal of magnesium ammonium phosphate. The recovered magnesium ammonium phosphate is sold to a manufacturer as a fertilizer raw material.
　本実施の形態の汚泥処理システム１において、消化槽１２には、薬剤を投入するための薬剤投入装置２４（薬剤投入量調整手段）が設けられている。この薬剤は、浮遊する微小な汚泥Ｗ１を付着させて効率よく沈殿させるための薬剤である。また、最終沈殿槽５と浮上濃縮槽１１とを繋ぐ配管２５の途中には超音波濃度計２６が設けられており、超音波濃度計２６によって最終沈殿槽５から排出される汚泥Ｗ１（被測定汚泥）の汚泥濃度が測定される。この超音波濃度計２６は、薬剤投入装置２４と電気的に接続されている。さらに、薬剤投入装置２４には、最初沈殿槽３と消化槽１２とを繋ぐ配管２１の途中に設けられている超音波濃度計２２が電気的に接続されている。そして、各超音波濃度計２２，２６で測定した汚泥濃度のデータが薬剤投入装置２４に入力される。薬剤投入装置２４は、各超音波濃度計２２，２６が測定した汚泥濃度に基づいて、消化槽１２に投入する薬剤の投入量を調整する。 In the sludge treatment system 1 of the present embodiment, the digestion tank 12 is provided with a chemical input device 24 (chemical input amount adjusting means) for supplying a chemical. This chemical is a chemical for allowing fine sludge W1 to float and deposit it efficiently. Further, an ultrasonic concentration meter 26 is provided in the middle of the pipe 25 connecting the final sedimentation tank 5 and the floating concentration tank 11, and the sludge W1 (measured object) discharged from the final sedimentation tank 5 by the ultrasonic concentration meter 26 is provided. Sludge concentration of sludge) is measured. The ultrasonic densitometer 26 is electrically connected to the medicine injection device 24. Furthermore, an ultrasonic densitometer 22 provided in the middle of a pipe 21 that initially connects the precipitation tank 3 and the digestion tank 12 is electrically connected to the medicine charging device 24. Then, the sludge concentration data measured by the ultrasonic densitometers 22 and 26 is input to the chemical injection device 24. The medicine feeding device 24 adjusts the amount of medicine to be fed into the digestion tank 12 based on the sludge concentration measured by the ultrasonic densitometers 22 and 26.
　また、汚泥処理システム１では、各超音波濃度計２２，２６で測定した汚泥濃度のデータが汚泥脱水機１３にも入力されており、汚泥濃度に基づいて汚泥脱水機１３の稼働率が調整される。 In the sludge treatment system 1, the sludge concentration data measured by the ultrasonic densitometers 22 and 26 is also input to the sludge dewatering machine 13, and the operating rate of the sludge dewatering machine 13 is adjusted based on the sludge density. The
　次に、本実施の形態で用いられる超音波濃度計２６の構成について、図２を用いて詳述する。なお、最初沈殿槽３と消化槽１２とを繋ぐ配管２１に設けた超音波濃度計２２も図２の超音波濃度計２６と同様の構造を有している。 Next, the configuration of the ultrasonic densitometer 26 used in the present embodiment will be described in detail with reference to FIG. Note that the ultrasonic densitometer 22 provided in the pipe 21 that first connects the precipitation tank 3 and the digestion tank 12 also has the same structure as the ultrasonic densitometer 26 of FIG.
　図２に示されるように、超音波濃度計２６は、円筒状の管本体３０と、４対の送信センサ３１及び受信センサ３２と、超音波発振器３３と、受信回路３４と、信号増幅回路３５と、コントローラ３６と、表示装置３７とを備える。超音波濃度計２６の管本体３０は、配管２５と接続されており、管本体３０内の流路において図２の上方から下方に汚泥Ｗ１が流れるようになっている。 As shown in FIG. 2, the ultrasonic densitometer 26 includes a cylindrical tube body 30, four pairs of transmission sensors 31 and reception sensors 32, an ultrasonic oscillator 33, a reception circuit 34, and a signal amplification circuit 35. And a controller 36 and a display device 37. The pipe main body 30 of the ultrasonic densitometer 26 is connected to the pipe 25, and the sludge W1 flows from the upper side to the lower side in FIG.
　各センサ３１，３２は、本実施形態では、管本体３０の側壁において汚泥Ｗ１の流通方向（管本体３０の軸方向）に沿って等間隔となる位置にそれぞれ設けられている。なお、各センサ３１，３２は必ずしも等間隔となる位置に設けられなくてもよい。また、対となる送信センサ３１と受信センサ３２とは、管本体３０の流路を挟んで対向する位置に設けられており、汚泥Ｗ１の流通方向に対して直交する方向に超音波Ｓ１の送受信を行う。 In this embodiment, the sensors 31 and 32 are provided at equal intervals along the flow direction of the sludge W1 (the axial direction of the pipe main body 30) on the side wall of the pipe main body 30, respectively. Note that the sensors 31 and 32 are not necessarily provided at equal intervals. The transmission sensor 31 and the reception sensor 32 that are paired are provided at positions facing each other with the flow path of the pipe main body 30 interposed therebetween, and transmit and receive the ultrasonic wave S1 in a direction orthogonal to the flow direction of the sludge W1. I do.
　超音波発振器３３は、送信センサ３１に接続されており、周波数の異なる駆動信号（具体的には、１ＭＨｚの駆動信号と３ＭＨｚの駆動信号）を生成して送信センサ３１に出力する。超音波発振器３３において、駆動信号の周波数の切り換えは、コントローラ３６から出力される制御信号に基づいて行われる。超音波送信手段としての送信センサ３１は、超音波発振器３３の駆動信号によって振動することにより、１ＭＨｚまたは３ＭＨｚの超音波Ｓ１を汚泥Ｗ１中に発信する。そして、超音波受信手段としての受信センサ３２によって、汚泥Ｗ１中を伝搬した超音波Ｓ１が受信される。 The ultrasonic oscillator 33 is connected to the transmission sensor 31, generates drive signals having different frequencies (specifically, a 1 MHz drive signal and a 3 MHz drive signal) and outputs the drive signals to the transmission sensor 31. In the ultrasonic oscillator 33, the frequency of the drive signal is switched based on a control signal output from the controller 36. The transmission sensor 31 as an ultrasonic transmission means transmits an ultrasonic wave S1 of 1 MHz or 3 MHz into the sludge W1 by vibrating with a drive signal of the ultrasonic oscillator 33. And the ultrasonic wave S1 which propagated in the sludge W1 is received by the receiving sensor 32 as an ultrasonic wave receiving means.
　受信回路３４は、受信センサ３２に接続されており、受信センサ３２で受信された超音波Ｓ１の受信信号を取得して信号増幅回路３５に出力する。信号増幅手段としての信号増幅回路３５は、超音波Ｓ１の受信信号を増幅してコントローラ３６に出力する。本実施の形態の信号増幅回路３５は、コントローラ３６から出力される制御信号に基づいて、信号増幅のゲインを調整可能に構成されている。 The reception circuit 34 is connected to the reception sensor 32, acquires the reception signal of the ultrasonic wave S <b> 1 received by the reception sensor 32, and outputs it to the signal amplification circuit 35. The signal amplification circuit 35 as signal amplification means amplifies the reception signal of the ultrasonic wave S1 and outputs it to the controller 36. The signal amplification circuit 35 according to the present embodiment is configured to be able to adjust the gain of signal amplification based on a control signal output from the controller 36.
　コントローラ３６は、周知のＣＰＵ３８（中央処理装置）やメモリ３９等を含んで構成されており、ＣＰＵ３８がメモリ３９を利用して制御プログラムを実行し、管本体３０を流れる汚泥Ｗ１の汚泥濃度を測定する。具体的には、コントローラ３６は、超音波Ｓ１の受信信号の強度から超音波減衰量（汚泥Ｗ１中を伝搬する超音波Ｓ１の減衰量）を求める。そして、コントローラ３６は、超音波減衰量に対する濃度の変換テーブルのデータを使用して、汚泥濃度を求める。なお、変換テーブルのデータは、工場出荷時等においてセンサ３１，３２毎に求められ、コントローラ３６のメモリ３９に予め記憶されている。また、超音波濃度計２６は、４ｃｈの測定部（送信センサ３１及び受信センサ３２）を備えているが、各測定部において、超音波Ｓ１の減衰量をそれぞれ求め、最も大きいものを除外した残り３つの平均値を用いて汚泥濃度を求めている。コントローラ３６は、その汚泥濃度を表示装置３７に表示させるとともに、汚泥濃度のデータを消化槽１２の薬剤投入装置２４や汚泥脱水機１３に出力する。なお、汚泥濃度を求める方法は上記の方法のみに限定されず、別の方法であってもよい。 The controller 36 includes a well-known CPU 38 (central processing unit), a memory 39, etc., and the CPU 38 executes a control program using the memory 39 to measure the sludge concentration of the sludge W1 flowing through the pipe body 30. To do. Specifically, the controller 36 obtains an ultrasonic attenuation amount (attenuation amount of the ultrasonic wave S1 propagating through the sludge W1) from the intensity of the received signal of the ultrasonic wave S1. And the controller 36 calculates | requires sludge density | concentration using the data of the conversion table of the density | concentration with respect to ultrasonic attenuation amount. The conversion table data is obtained for each of the sensors 31 and 32 at the time of factory shipment or the like, and stored in the memory 39 of the controller 36 in advance. The ultrasonic densitometer 26 includes a 4-channel measurement unit (transmission sensor 31 and reception sensor 32). In each measurement unit, the attenuation amount of the ultrasonic wave S1 is obtained, and the remaining one excluding the largest one is excluded. The sludge concentration is obtained using three average values. The controller 36 displays the sludge concentration on the display device 37 and outputs the sludge concentration data to the chemical charging device 24 and the sludge dehydrator 13 of the digestion tank 12. In addition, the method of calculating | requiring a sludge density | concentration is not limited only to said method, Another method may be sufficient.
　本実施の形態の超音波濃度計２６は、汚泥濃度が低い場合に３ＭＨｚ（第１の周波数）の超音波Ｓ１を利用して汚泥濃度を測定し、汚泥濃度が高い場合には１ＭＨｚ（第２の周波数）の超音波Ｓ１を利用して汚泥濃度を測定するよう構成されている。 The ultrasonic densitometer 26 of the present embodiment measures the sludge concentration using the ultrasonic wave S1 of 3 MHz (first frequency) when the sludge concentration is low, and 1 MHz (second) when the sludge concentration is high. The sludge concentration is measured by using the ultrasonic wave S1 having a frequency of 1).
　図３には、１ＭＨｚ及び３ＭＨｚの超音波Ｓ１の減衰量と汚泥濃度との関係を示している。図３に示されるように、３ＭＨｚの超音波Ｓ１の場合（線分Ｌ１の場合）は、汚泥濃度が０％の水でも減衰し、所定の汚泥濃度（例えば７％）以上となると濃度が増加しても減衰量が変化せず飽和してしまう。なお、３ＭＨｚの超音波Ｓ１の場合、直線性を示すのは５％未満の濃度である。一方、１ＭＨｚの超音波Ｓ１の場合（線分Ｌ２の場合）、汚泥濃度が比較的高くなっても、減衰量と汚泥濃度との関係が直線性を示しているが、汚泥濃度が低くなる（例えば、３％未満となる）と超音波Ｓ１が殆ど減衰しなくなる。 FIG. 3 shows the relationship between the attenuation amount of the ultrasonic wave S1 of 1 MHz and 3 MHz and the sludge concentration. As shown in FIG. 3, in the case of the ultrasonic wave S1 of 3 MHz (in the case of the line segment L1), the sludge concentration is attenuated even with 0% water, and the concentration increases when the sludge concentration exceeds a predetermined sludge concentration (for example, 7%). Even so, the attenuation does not change and is saturated. In the case of the ultrasonic wave S1 of 3 MHz, the concentration that shows linearity is less than 5%. On the other hand, in the case of 1 MHz ultrasonic wave S1 (in the case of line segment L2), even if the sludge concentration is relatively high, the relationship between the attenuation and the sludge concentration shows linearity, but the sludge concentration is low ( For example, when it is less than 3%, the ultrasonic wave S1 hardly attenuates.
　このように、３ＭＨｚの超音波Ｓ１は、低濃度域の測定に適しているが、高濃度域を測定することができない。一方、１ＭＨｚの超音波Ｓ１は、高濃度域の測定に適しているが、低濃度を測定することができない。従って、本実施の形態の超音波濃度計２６では、自動切換変移点Ｐ１を設定し、その変移点Ｐ１に対応した設定濃度値で超音波Ｓ１の周波数を切り換えて汚泥濃度を測定している。具体的には、汚泥濃度が減少して高濃度側から自動切換変移点Ｐ１の設定濃度値に到達したときに、１ＭＨｚの周波数から３ＭＨｚの周波数に超音波Ｓ１の周波数が自動的に切り換えられる。一方、汚泥濃度が増加して低濃度側から自動切換変移点Ｐ１の設定濃度値に到達したときに、３ＭＨｚの周波数から１ＭＨｚの周波数に超音波Ｓ１の周波数が自動的に切り換えられる。なお、自動切換変移点Ｐ１に対応した設定濃度値は、３ＭＨｚ及び１ＭＨｚの各超音波Ｓ１について、汚泥濃度に対する超音波減衰量の変化量が直線的な関係を有する領域に設定される。 Thus, although the 3 MHz ultrasonic wave S1 is suitable for the measurement in the low concentration region, it cannot measure the high concentration region. On the other hand, the ultrasonic wave S1 of 1 MHz is suitable for measurement in a high concentration region, but cannot measure a low concentration. Therefore, in the ultrasonic densitometer 26 of the present embodiment, the automatic switching transition point P1 is set, and the sludge concentration is measured by switching the frequency of the ultrasonic wave S1 with the set concentration value corresponding to the transition point P1. Specifically, when the sludge concentration decreases and reaches the set concentration value of the automatic switching transition point P1 from the high concentration side, the frequency of the ultrasonic wave S1 is automatically switched from the frequency of 1 MHz to the frequency of 3 MHz. On the other hand, when the sludge concentration increases and reaches the set concentration value of the automatic switching transition point P1 from the low concentration side, the frequency of the ultrasonic wave S1 is automatically switched from the frequency of 3 MHz to the frequency of 1 MHz. The set concentration value corresponding to the automatic switching transition point P1 is set in a region where the amount of change in ultrasonic attenuation with respect to the sludge concentration has a linear relationship with respect to each of the ultrasonic waves S1 of 3 MHz and 1 MHz.
　また、本発明者らは、１ＭＨｚの超音波Ｓ１を用いる場合、信号増幅の感度調整を最適化することにより、低濃度側の測定可能領域が拡がることを実験によって導き出した。具体的には、信号増幅回路３５におけるゲインが低くなるよう調整することで、図３において一点鎖線の線分Ｌ３で示すように、低濃度（例えば２％程度）の汚泥Ｗ１まで濃度測定が可能となった。従って、超音波濃度計２６では、３ＭＨｚの超音波Ｓ１で測定した汚泥濃度に基づいて、１ＭＨｚの超音波Ｓ１に対する信号増幅のゲインを調整するよう構成している。なお、超音波濃度計２６では、４ｃｈの受信センサ３２及び受信回路３４を備えているが、４ｃｈの受信信号毎に信号増幅のゲインを調整している。また、信号増幅のゲインを低下させた場合、減衰量と汚泥濃度との関係において直線性を示す測定領域が低濃度側にシフトするため、自動切換変移点Ｐ１に対応した設定濃度値を低濃度側（例えば、４％から３％の濃度値）に変更している。 In addition, when the present inventors used 1 MHz ultrasonic wave S1, the inventors have experimentally derived that the measurable region on the low concentration side is expanded by optimizing the sensitivity adjustment of signal amplification. Specifically, by adjusting the gain in the signal amplification circuit 35 to be low, the concentration can be measured up to sludge W1 having a low concentration (for example, about 2%) as shown by a dashed line L3 in FIG. It became. Therefore, the ultrasonic densitometer 26 is configured to adjust the gain of signal amplification for the ultrasonic wave S1 of 1 MHz based on the sludge concentration measured by the ultrasonic wave S1 of 3 MHz. The ultrasonic densitometer 26 includes a 4ch reception sensor 32 and a reception circuit 34, but adjusts the gain of signal amplification for each 4ch reception signal. In addition, when the signal amplification gain is reduced, the measurement region showing linearity in the relationship between the attenuation and the sludge concentration shifts to the low concentration side, so the set concentration value corresponding to the automatic switching transition point P1 is set to the low concentration. (For example, a density value of 4% to 3%).
　次に、本実施の形態の超音波濃度計２６においてコントローラ３６が実行する汚泥濃度測定処理の具体例について、図４及び図５のフローチャートを用いて説明する。なお、図４の処理は、汚泥処理システム１の稼動時において、図示しない電源ボタンがオン操作されたときに、超音波濃度計２６の初期化処理として実行される。また、図５の処理は、図４の初期化処理の後、所定期間毎（例えば、１秒毎）に実行される。 Next, a specific example of the sludge concentration measurement process executed by the controller 36 in the ultrasonic densitometer 26 of the present embodiment will be described with reference to the flowcharts of FIGS. 4 and 5. 4 is executed as an initialization process of the ultrasonic concentration meter 26 when a power button (not shown) is turned on while the sludge treatment system 1 is in operation. 5 is executed every predetermined period (for example, every second) after the initialization process of FIG.
　図４に示されるように、コントローラ３６は、３ＭＨｚの超音波Ｓ１を利用して汚泥濃度を測定する（ステップ１００）。具体的には、コントローラ３６は、超音波発振器３３に制御信号を出力し、超音波発振器３３から各送信センサ３１に３ＭＨｚの駆動信号を出力させる。このとき、送信センサ３１から管本体３０の汚泥Ｗ１中に３ＭＨｚの超音波Ｓ１が出力されるとともに、汚泥Ｗ１中を伝搬した超音波Ｓ１が受信センサ３２で受信される。そして、その超音波Ｓ１の受信信号が受信回路３４で取得され、信号増幅回路３５で信号増幅された後、コントローラ３６に取り込まれる。コントローラ３６は、超音波Ｓ１の受信信号の強度に基づいて、超音波減衰量を求める。そして、コントローラ３６は、メモリ３９に記憶されている変換テーブルのデータを用いて、超音波減衰量に応じた汚泥濃度を演算にて求める。 As shown in FIG. 4, the controller 36 measures the sludge concentration using 3 MHz ultrasonic waves S1 (step 100). Specifically, the controller 36 outputs a control signal to the ultrasonic oscillator 33 and causes each transmission sensor 31 to output a drive signal of 3 MHz from the ultrasonic oscillator 33. At this time, the ultrasonic wave S1 of 3 MHz is output from the transmission sensor 31 into the sludge W1 of the pipe body 30, and the ultrasonic wave S1 propagated through the sludge W1 is received by the reception sensor 32. Then, the reception signal of the ultrasonic wave S1 is acquired by the reception circuit 34, amplified by the signal amplification circuit 35, and then taken into the controller 36. The controller 36 obtains an ultrasonic attenuation amount based on the intensity of the received signal of the ultrasonic wave S1. And the controller 36 calculates | requires the sludge density | concentration according to an ultrasonic attenuation amount by calculation using the data of the conversion table memorize | stored in the memory 39. FIG.
　次に、コントローラ３６は、３ＭＨｚの超音波Ｓ１を用いて測定した汚泥濃度に基づいて、信号増幅回路３５に制御信号を出力し、１ＭＨｚの超音波Ｓ１に対応する信号増幅のゲインを調整する（ステップ１１０）。詳しくは、汚泥濃度が、例えば３％以上である場合、信号増幅のゲインを高い値に設定し、３％未満である場合には、信号増幅のゲインを低い値に設定する。また、各ｃｈの送信センサ３１及び受信センサ３２は、素子バラツキにより受信回路３４で得られる受信信号の信号強度が異なる。従って、ステップ１１０では、素子バラツキを緩和するように各ｃｈのゲインが調整される。 Next, the controller 36 outputs a control signal to the signal amplification circuit 35 based on the sludge concentration measured using the 3 MHz ultrasonic wave S1, and adjusts the gain of signal amplification corresponding to the 1 MHz ultrasonic wave S1 ( Step 110). Specifically, when the sludge concentration is, for example, 3% or more, the signal amplification gain is set to a high value, and when it is less than 3%, the signal amplification gain is set to a low value. Further, the transmission sensor 31 and the reception sensor 32 of each channel have different signal strengths of reception signals obtained by the reception circuit 34 due to element variations. Therefore, in step 110, the gain of each channel is adjusted so as to reduce the element variation.
　その後、設定濃度値変更手段としてのコントローラ３６は、超音波Ｓ１の周波数を変更するための自動切換変移点Ｐ１に対応した設定濃度値を設定してメモリ３９に記憶する（ステップ１２０）。具体的には、汚泥濃度が、例えば３％以上である場合、自動切換変移点Ｐ１に対応した設定濃度値を４％に設定し、３％未満である場合には、自動切換変移点Ｐ１に対応した設定濃度値を３％に設定する。このように、本実施の形態では、３ＭＨｚの超音波Ｓ１で測定した汚泥濃度に基づいて、自動切換変移点Ｐ１に対応した設定濃度値を切り換えるように構成している。 Thereafter, the controller 36 as the set density value changing means sets a set density value corresponding to the automatic switching transition point P1 for changing the frequency of the ultrasonic wave S1, and stores it in the memory 39 (step 120). Specifically, when the sludge concentration is 3% or more, for example, the set concentration value corresponding to the automatic switching transition point P1 is set to 4%, and when it is less than 3%, the automatic switching transition point P1 is set. The corresponding set density value is set to 3%. As described above, in the present embodiment, the set concentration value corresponding to the automatic switching transition point P1 is switched based on the sludge concentration measured by the ultrasonic wave S1 of 3 MHz.
　自動切換変移点Ｐ１の設定後、測定用周波数切換手段としてのコントローラ３６は、ステップ１００で測定した汚泥濃度が自動切換変移点Ｐ１に対応した設定濃度値以上であるか否かを判定する（ステップ１３０）。ここで、汚泥濃度が設定濃度値以上である場合には、コントローラ３６は、超音波発振器３３に制御信号を出力し、超音波発振器３３から出力する駆動信号を１ＭＨｚの信号に変更し（ステップ１４０）、図４の処理を終了する。一方、設定濃度値未満である場合、超音波発振器３３の駆動信号の周波数を３ＭＨｚから変更せず、図４の処理を終了する。 After setting the automatic switching transition point P1, the controller 36 as the measurement frequency switching means determines whether or not the sludge concentration measured in step 100 is equal to or higher than the set concentration value corresponding to the automatic switching transition point P1 (step). 130). Here, if the sludge concentration is equal to or higher than the set concentration value, the controller 36 outputs a control signal to the ultrasonic oscillator 33 and changes the drive signal output from the ultrasonic oscillator 33 to a signal of 1 MHz (step 140). ), The process of FIG. On the other hand, if it is less than the set concentration value, the frequency of the drive signal of the ultrasonic oscillator 33 is not changed from 3 MHz, and the processing of FIG.
　その後、コントローラ３６は、図５の処理を実行する。すなわち、コントローラ３６は、図４の処理で設定した周波数の駆動信号を超音波発振器３３から出力させ、送信センサ３１及び受信センサ３２でその周波数の超音波Ｓ１を送受信させる。そして、コントローラ３６は、得られた超音波Ｓ１の受信信号に基づいて、汚泥濃度を求める（ステップ２００）。 Thereafter, the controller 36 executes the processing of FIG. That is, the controller 36 causes the ultrasonic oscillator 33 to output a drive signal having the frequency set in the processing of FIG. 4, and causes the transmission sensor 31 and the reception sensor 32 to transmit / receive the ultrasonic wave S <b> 1 having that frequency. And the controller 36 calculates | requires sludge density | concentration based on the received signal of the obtained ultrasonic wave S1 (step 200).
　次に、濃度判定手段としてのコントローラ３６は、ステップ２００で測定した汚泥濃度が自動切換変移点Ｐ１に対応した設定濃度値に到達したか否かを判定する（ステップ２１０）。そして、汚泥濃度が設定濃度値に到達したと判定したとき、測定用周波数切換手段としてのコントローラ３６は、超音波Ｓ１の周波数を別のものに自動的に切り換えて、汚泥濃度を再測定する（ステップ２２０）。 Next, the controller 36 as the concentration determination means determines whether or not the sludge concentration measured in step 200 has reached the set concentration value corresponding to the automatic switching transition point P1 (step 210). When it is determined that the sludge concentration has reached the set concentration value, the controller 36 as the measurement frequency switching means automatically switches the frequency of the ultrasonic wave S1 to another one and remeasures the sludge concentration ( Step 220).
　具体的には、１ＭＨｚの超音波Ｓ１で汚泥濃度を測定している場合、汚泥濃度が減少して高濃度側から設定濃度値に到達したとき、コントローラ３６は、送信センサ３１から出力される超音波の周波数（超音波発振器３３の駆動信号）を１ＭＨｚから３ＭＨｚに切り替えて、汚泥濃度を再測定する。また、３ＭＨｚの超音波Ｓ１で汚泥濃度を測定している場合、汚泥濃度が増加して低濃度側から設定濃度値に到達したとき、コントローラ３６は、送信センサ３１から出力される超音波Ｓ１の周波数（超音波発振器３３の駆動信号）を３ＭＨｚから１ＭＨｚに切り替えて、汚泥濃度を再測定する。その後、コントローラ３６は、ステップ２２０で再測定した汚泥濃度のデータを表示装置３７、薬剤投入装置２４及び汚泥脱水機１３に出力する（ステップ２３０）。このとき、汚泥濃度が表示装置３７に表示される。 Specifically, when the sludge concentration is measured by the ultrasonic wave S1 of 1 MHz, when the sludge concentration decreases and reaches the set concentration value from the high concentration side, the controller 36 outputs the superfluid output from the transmission sensor 31. The frequency of sound waves (drive signal of the ultrasonic oscillator 33) is switched from 1 MHz to 3 MHz, and the sludge concentration is measured again. Further, when the sludge concentration is measured with the ultrasonic wave S1 of 3 MHz, when the sludge concentration increases and reaches the set concentration value from the low concentration side, the controller 36 outputs the ultrasonic wave S1 output from the transmission sensor 31. The frequency (drive signal of the ultrasonic oscillator 33) is switched from 3 MHz to 1 MHz, and the sludge concentration is measured again. Thereafter, the controller 36 outputs the sludge concentration data remeasured in step 220 to the display device 37, the chemical charging device 24, and the sludge dehydrator 13 (step 230). At this time, the sludge concentration is displayed on the display device 37.
　一方、コントローラ３６は、汚泥濃度が設定濃度値に到達していないと判定したときには、超音波Ｓ１の周波数（超音波発振器３３の駆動信号）を切り換えないまま、ステップ２３０に移行する。そして、コントローラ３６は、ステップ２００で測定した汚泥濃度のデータを表示装置３７、薬剤投入装置２４及び汚泥脱水機１３に出力する。このとき、汚泥濃度が表示装置３７に表示される。 On the other hand, when the controller 36 determines that the sludge concentration has not reached the set concentration value, the controller 36 proceeds to Step 230 without switching the frequency of the ultrasonic wave S1 (the drive signal of the ultrasonic oscillator 33). Then, the controller 36 outputs the sludge concentration data measured in step 200 to the display device 37, the chemical injection device 24 and the sludge dehydrator 13. At this time, the sludge concentration is displayed on the display device 37.
　そして、コントローラ３６は、汚泥濃度のデータ出力後に、電源ボタンがオフ操作されたか否かを判定し（ステップ２４０）、オフ操作された場合には、図５の処理を終了する。一方、電源ボタンがオンである場合には、コントローラ３６は、ステップ２００の処理に戻り、ステップ２００~ステップ２４０の処理を繰り返し実行する。 Then, the controller 36 determines whether or not the power button is turned off after the sludge concentration data is output (step 240). If the power button is turned off, the process of FIG. 5 is terminated. On the other hand, if the power button is on, the controller 36 returns to the process of step 200 and repeatedly executes the processes of step 200 to step 240.
　従って、本実施の形態によれば以下の効果を得ることができる。 Therefore, according to the present embodiment, the following effects can be obtained.
　（１）本実施の形態の超音波濃度計２６では、汚泥濃度が自動切換変移点Ｐ１に対応した設定濃度値に到達したときに、汚泥濃度の演算に用いる超音波Ｓ１の周波数が自動的に切り換えられる。そして、汚泥濃度が設定濃度値よりも低い場合、低濃度域の測定に適した３ＭＨｚの超音波Ｓ１を用いて汚泥濃度が求められ、汚泥濃度が設定濃度値よりも高い場合には、高濃度域の測定に適した１ＭＨｚの超音波Ｓ１を用いて汚泥濃度が求められる。このようにすると、汚泥濃度を低濃度から高濃度まで正確に求めることができる。 (1) In the ultrasonic densitometer 26 of the present embodiment, when the sludge concentration reaches a set concentration value corresponding to the automatic switching transition point P1, the frequency of the ultrasonic wave S1 used for calculating the sludge concentration is automatically set. Can be switched. When the sludge concentration is lower than the set concentration value, the sludge concentration is obtained using the 3 MHz ultrasonic wave S1 suitable for the measurement in the low concentration range. When the sludge concentration is higher than the set concentration value, the high concentration is obtained. The sludge concentration is determined using 1 MHz ultrasonic wave S1 suitable for the measurement of the area. In this way, the sludge concentration can be accurately determined from a low concentration to a high concentration.
　（２）本実施の形態の超音波濃度計２６では、濃度測定に用いる超音波Ｓ１の周波数を、第１の周波数としての３ＭＨｚと第２の周波数としての１ＭＨｚとで切り換えている。第１の周波数としての３ＭＨｚの周波数は、第２の周波数としての１ＭＨｚの周波数（基本波）の３倍の周波数（第３高調波）となっている。この場合、送信センサ３１を構成する圧電素子を各周波数で効率よく振動させることができ、送信センサ３１から各周波数の超音波Ｓ１を効率よく確実に発信させることができる。 (2) In the ultrasonic densitometer 26 of the present embodiment, the frequency of the ultrasonic wave S1 used for concentration measurement is switched between 3 MHz as the first frequency and 1 MHz as the second frequency. The frequency of 3 MHz as the first frequency is a frequency (third harmonic) that is three times the frequency (fundamental wave) of 1 MHz as the second frequency. In this case, the piezoelectric element constituting the transmission sensor 31 can be vibrated efficiently at each frequency, and the ultrasonic wave S1 of each frequency can be transmitted from the transmission sensor 31 efficiently and reliably.
　（３）本実施の形態の超音波濃度計２６では、３ＭＨｚの超音波Ｓ１を用いて演算した汚泥濃度に基づいて、１ＭＨｚの超音波Ｓ１に対応する信号増幅のゲインを最適化することができる。このようにすると、１ＭＨｚの超音波Ｓ１を用いて測定することが可能な濃度範囲を拡げることができる。 (3) In the ultrasonic densitometer 26 of the present embodiment, the gain of signal amplification corresponding to the ultrasonic wave S1 of 1 MHz can be optimized based on the sludge concentration calculated using the ultrasonic wave S1 of 3 MHz. . In this way, the concentration range that can be measured using the 1 MHz ultrasonic wave S1 can be expanded.
　（４）本実施の形態の超音波濃度計２６では、送信センサ３１及びそれに対向して配置される受信センサ３２が複数対設けられる。従って、それぞれ送信センサ３１及び受信センサ３２で測定した汚泥濃度を平均化することで、測定誤差を低く抑えることができる。また、受信センサ３２毎に信号増幅のゲインが調整されるので、各センサ３１，３２における素子特性のバラツキを補正することができ、測定精度を高めることができる。 (4) In the ultrasonic densitometer 26 of the present embodiment, a plurality of pairs of transmission sensors 31 and reception sensors 32 arranged to face the transmission sensors 31 are provided. Therefore, by averaging the sludge concentrations measured by the transmission sensor 31 and the reception sensor 32, the measurement error can be suppressed low. In addition, since the gain of signal amplification is adjusted for each reception sensor 32, variations in element characteristics in the sensors 31 and 32 can be corrected, and measurement accuracy can be improved.
　（５）本実施の形態の超音波濃度計２６では、１ＭＨｚの超音波Ｓ１に対応する信号増幅のゲインの調整後に、超音波Ｓ１の周波数が３ＭＨｚから１ＭＨｚに切り換えられるので、１ＭＨｚの超音波Ｓ１を用いて汚泥濃度を正確に測定することができる。また、信号増幅回路３５によって信号増幅のゲインが低くなるように調整されたときに、設定濃度値が低濃度側に変更される。この結果、１ＭＨｚの超音波Ｓ１を用いて測定することが可能な濃度範囲を拡げることができる。 (5) In the ultrasonic densitometer 26 of the present embodiment, the frequency of the ultrasonic wave S1 is switched from 3 MHz to 1 MHz after adjusting the gain of signal amplification corresponding to the ultrasonic wave S1 of 1 MHz, so the ultrasonic wave S1 of 1 MHz. Can be used to accurately measure the sludge concentration. When the signal amplification circuit 35 adjusts the gain of signal amplification to be low, the set density value is changed to the low density side. As a result, the concentration range that can be measured using the ultrasonic wave S1 of 1 MHz can be expanded.
　（６）本実施の形態の汚泥処理システム１では、下水道施設の最終沈殿槽５から排出された汚泥Ｗ１の汚泥濃度が超音波濃度計２６によって測定され、その汚泥濃度に応じて消化槽１２に投入する薬剤の投入量を最適に調整することができる。このようにすると、薬剤が無駄に使用されることがなく、汚泥処理システム１のランニングコストを低く抑えることができる。また、最終沈殿槽５から排出される汚泥濃度は通常３％~１１％程度の濃度であるが、例えば曝気槽４における処理異常が発生して汚泥濃度が３％未満となった場合や１１％を超えた場合でも、超音波濃度計２６における超音波Ｓ１の周波数を適宜切り換えることで、汚泥濃度を正確に測定することができる。そして、汚泥濃度に応じて最適な投入量の薬剤が消化槽１２に投入されることにより、汚泥処理を効率よく確実に行うことができる。このように汚泥処理システム１を構成すると、比較的容積の小さな消化槽１２を用いることができ、設備コストを低減することができる。 (6) In the sludge treatment system 1 of the present embodiment, the sludge concentration of the sludge W1 discharged from the final sedimentation tank 5 of the sewer facility is measured by the ultrasonic densitometer 26, and the digestion tank 12 is supplied according to the sludge concentration. It is possible to optimally adjust the amount of medicine to be introduced. If it does in this way, a chemical | medical agent will not be used wastefully and the running cost of the sludge treatment system 1 can be restrained low. The concentration of sludge discharged from the final sedimentation tank 5 is usually about 3% to 11%. For example, when a processing abnormality occurs in the aeration tank 4 and the sludge concentration becomes less than 3%, or 11% Even if the frequency exceeds the value, the sludge concentration can be accurately measured by appropriately switching the frequency of the ultrasonic wave S1 in the ultrasonic densitometer 26. Then, by introducing an optimal amount of medicine into the digestion tank 12 according to the sludge concentration, the sludge treatment can be performed efficiently and reliably. When the sludge treatment system 1 is configured in this way, the digester tank 12 having a relatively small volume can be used, and the equipment cost can be reduced.
　（７）本実施の形態の汚泥処理システム１では、超音波濃度計２６が測定した汚泥濃度に基づいて、汚泥脱水機１３の稼働率が調整される。この場合、汚泥脱水機１３が最適な状態で稼動されるため、その消費電力を低く抑えることができ、汚泥処理システム１のランニングコストを低減することができる。 (7) In the sludge treatment system 1 of the present embodiment, the operating rate of the sludge dehydrator 13 is adjusted based on the sludge concentration measured by the ultrasonic densitometer 26. In this case, since the sludge dehydrator 13 is operated in an optimum state, the power consumption can be kept low, and the running cost of the sludge treatment system 1 can be reduced.
　なお、本発明の実施の形態は以下のように変更してもよい。 The embodiment of the present invention may be modified as follows.
　・上記実施の形態の超音波濃度計２６では、表示装置３７に汚泥濃度を表示していたが、これに限定されるものではない。例えば、汚泥処理システム１で正常稼動時には起こりえない汚泥濃度が測定された場合に、その汚泥濃度とともに警告メッセージ等を表示装置３７に表示するように構成してもよい。さらに、表示装置３７において、汚泥濃度を表示するとともに、図３に示すような汚泥濃度と超音波Ｓ１の減衰量との関係を示す線分Ｌ１，Ｌ２，Ｌ３を有するグラフを超音波Ｓ１の周波数毎に表示してもよい。さらには、表示装置３７において、汚泥濃度と超音波Ｓ１の減衰量との関係を示す線分Ｌ１，Ｌ２，Ｌ３を有するグラフ中において周波数の自動切換変移点Ｐ１に対応した設定濃度値を示す直線Ｌ４を表示してもよい。 In the ultrasonic densitometer 26 of the above embodiment, the sludge concentration is displayed on the display device 37, but the present invention is not limited to this. For example, when a sludge concentration that cannot occur during normal operation in the sludge treatment system 1 is measured, a warning message or the like may be displayed on the display device 37 together with the sludge concentration. Further, on the display device 37, the sludge concentration is displayed and a graph having line segments L1, L2, L3 indicating the relationship between the sludge concentration and the attenuation amount of the ultrasonic wave S1 as shown in FIG. It may be displayed every time. Further, in the display device 37, a straight line indicating the set concentration value corresponding to the frequency automatic switching transition point P1 in the graph having line segments L1, L2, and L3 indicating the relationship between the sludge concentration and the attenuation amount of the ultrasonic wave S1. L4 may be displayed.
　また、図６に示される汚泥処理システム１のように、警報装置４１を別途設け、超音波濃度計２６から出力される汚泥濃度のデータに基づいて、汚泥濃度が異常値になった場合に、システム異常である旨を警告ブザーや警告ランプ等を用いて通知するように構成してもよい。 Further, as in the sludge treatment system 1 shown in FIG. 6, an alarm device 41 is provided separately, and when the sludge concentration becomes an abnormal value based on the sludge concentration data output from the ultrasonic densitometer 26, You may comprise so that it may notify that it is system abnormality using a warning buzzer, a warning lamp, etc. FIG.
　・上記実施の形態の超音波濃度計２６では、初期化処理として３ＭＨｚの超音波Ｓ１で測定した汚泥濃度に応じて自動切換変移点Ｐ１に対応した設定濃度値を設定していたが、これに限定されるものではない。一般に、下水処理場の汚泥処理システム１では、季節に応じて曝気槽４等の処理能力が異なり、最終沈殿槽５から排出される汚泥Ｗ１の濃度も変化する。具体的には、降雨量が多く比較的暖かい季節では、曝気槽４の微生物が活発に働くため、汚泥濃度が低くなる傾向にある。逆に、降雨量が少なく気温が低くなる季節では、汚泥濃度が高くなる傾向にある。従って、汚泥Ｗ１の温度を測定し、その温度に基づいて自動切換変移点Ｐ１に対応した設定濃度値を変更するよう超音波濃度計２６を構成してもよい。なおこの場合、超音波濃度計２６とは別に温度計を設けてもよいし、超音波濃度計２６に温度計の機能（温度測定手段）を付加してもよい。温度計の機能を付加する場合、超音波濃度計２６において、超音波Ｓ１の伝搬時間を計測するためのタイマを設け、タイマが計測した超音波Ｓ１の伝搬時間をコントローラ３６に取り込む。そして、温度測定手段としてのコントローラ３６がその伝搬時間に基づいて汚泥Ｗ１の温度を測定するよう構成する。 In the ultrasonic densitometer 26 of the above embodiment, the set concentration value corresponding to the automatic switching transition point P1 is set according to the sludge concentration measured by the ultrasonic S1 of 3 MHz as the initialization process. It is not limited. In general, in the sludge treatment system 1 in the sewage treatment plant, the treatment capacity of the aeration tank 4 and the like varies depending on the season, and the concentration of the sludge W1 discharged from the final sedimentation tank 5 also changes. Specifically, in a relatively warm season with a lot of rainfall, the microorganisms in the aeration tank 4 work actively, so that the sludge concentration tends to be low. Conversely, in the season when the rainfall is low and the temperature is low, the sludge concentration tends to be high. Therefore, the ultrasonic concentration meter 26 may be configured to measure the temperature of the sludge W1 and change the set concentration value corresponding to the automatic switching transition point P1 based on the temperature. In this case, a thermometer may be provided separately from the ultrasonic densitometer 26, or a thermometer function (temperature measuring means) may be added to the ultrasonic densitometer 26. When adding the function of a thermometer, the ultrasonic densitometer 26 is provided with a timer for measuring the propagation time of the ultrasonic wave S1, and the propagation time of the ultrasonic wave S1 measured by the timer is taken into the controller 36. And the controller 36 as a temperature measurement means is comprised so that the temperature of the sludge W1 may be measured based on the propagation time.
　また、季節の変わり目などでは汚泥濃度が急激に変化する。このため、１ＭＨｚの周波数を用いた測定時における特定の汚泥濃度（例えば、５％の濃度）での減衰量の変化率に基づいて自動切換変移点Ｐ１に対応した設定濃度値を変更してもよい。また、３ＭＨｚの周波数を用いた測定時における特定の汚泥濃度（例えば、２％の濃度）での減衰量の変化率に基づいて、自動切換変移点Ｐ１に対応した設定濃度値を変更してもよい。さらに、汚泥処理システム１を統括する制御装置（図示略）から超音波濃度計２６に日付情報や天候情報（降雨量など）のデータを入力し、それらデータに応じて自動切換変移点Ｐ１に対応した設定濃度値を変更するよう超音波濃度計２６を構成してもよい。 Also, the sludge concentration changes abruptly at the turn of the season. For this reason, even if the set concentration value corresponding to the automatic switching transition point P1 is changed based on the rate of change in attenuation at a specific sludge concentration (for example, a concentration of 5%) at the time of measurement using a frequency of 1 MHz. Good. Further, even if the set concentration value corresponding to the automatic switching transition point P1 is changed based on the rate of change of attenuation at a specific sludge concentration (for example, 2% concentration) at the time of measurement using a frequency of 3 MHz. Good. Furthermore, data of date information and weather information (rainfall, etc.) is input to the ultrasonic densitometer 26 from a control device (not shown) that supervises the sludge treatment system 1 and corresponds to the automatic switching transition point P1 according to the data. The ultrasonic densitometer 26 may be configured to change the set density value.
　・上記実施の形態の超音波濃度計２６では、汚泥濃度の減少時に超音波Ｓ１の周波数を１ＭＨｚから３ＭＨｚに切り換える場合と汚泥濃度の増加時に３ＭＨｚから１ＭＨｚに切り換える場合とで同じ設定濃度値を用いていたが、これに限定されるものではない。１ＭＨｚから３ＭＨｚに切り換える場合と３ＭＨｚから１ＭＨｚに切り換える場合とで、異なる設定濃度値を用いて超音波Ｓ１の周波数を切り換えるよう構成してもよい。 In the ultrasonic densitometer 26 of the above embodiment, the same set concentration value is used when the frequency of the ultrasonic wave S1 is switched from 1 MHz to 3 MHz when the sludge concentration is decreased and when the frequency is switched from 3 MHz to 1 MHz when the sludge concentration is increased. However, the present invention is not limited to this. You may comprise so that the frequency of the ultrasonic wave S1 may be switched using a different setting density value by the case where it switches from 1 MHz to 3 MHz, and the case where it switches from 3 MHz to 1 MHz.
　・上記実施の形態の超音波濃度計２６では、３ＭＨｚの超音波Ｓ１で測定した汚泥濃度に基づいて、１ＭＨｚの超音波Ｓ１に対する信号増幅のゲインを自動的に調整するよう構成していたがこれに限定されるものではない。これとは逆に、１ＭＨｚの超音波Ｓ１で測定した汚泥濃度に基づいて、３ＭＨｚの超音波Ｓ１に対する信号増幅のゲインを自動的に調整するよう超音波濃度計２６を構成してもよい。 In the ultrasonic densitometer 26 of the above embodiment, the signal amplification gain for the 1 MHz ultrasonic wave S1 is automatically adjusted based on the sludge concentration measured by the 3 MHz ultrasonic wave S1. It is not limited to. On the contrary, the ultrasonic densitometer 26 may be configured to automatically adjust the gain of signal amplification for the ultrasonic wave S1 of 3 MHz based on the sludge concentration measured by the ultrasonic wave S1 of 1 MHz.
　・上記実施の形態の超音波濃度計２６では、４ｃｈの送信センサ３１及び受信センサ３２を備えるものであったが、送信センサ３１及び受信センサ３２のｃｈ数は適宜変更してもよい。また、超音波濃度計２６では、１ＭＨｚ及び３ＭＨｚの超音波Ｓ１を利用して汚泥濃度を求めるように構成したが、他の異なる周波数の超音波Ｓ１を利用して汚泥濃度を求めてもよい。但し、上記実施の形態のように、基本波とその第３高調波とで周波数を切り換えるように構成することが好ましい。このように構成すると、１つの送信センサ３１から周波数の異なる超音波Ｓ１を効率よく出力することができる。 In the ultrasonic densitometer 26 of the above embodiment, the 4ch transmission sensor 31 and the reception sensor 32 are provided, but the number of channels of the transmission sensor 31 and the reception sensor 32 may be changed as appropriate. The ultrasonic densitometer 26 is configured to obtain the sludge concentration using the ultrasonic waves S1 of 1 MHz and 3 MHz. However, the sludge concentration may be obtained using the ultrasonic waves S1 having other different frequencies. However, it is preferable that the frequency is switched between the fundamental wave and its third harmonic as in the above embodiment. If comprised in this way, the ultrasonic wave S1 from which the frequency differs from one transmission sensor 31 can be output efficiently.
　・上記実施の形態の超音波濃度計２６において、管本体３０の流路を挟んで対向する位置に送信センサ３１と受信センサ３２とを設け、汚泥Ｗ１の流通方向に対して直交する方向に超音波Ｓ１の送受信を行うものであったが、これに限定されるものではない。例えば、汚泥Ｗ１の流通方向と平行に超音波Ｓ１の送受信を行うように送信センサ３１及び受信センサ３２を設けてもよい。また、汚泥Ｗ１の流通方向に対して傾斜した状態で超音波Ｓ１の送受信を行うように送信センサ３１及び受信センサ３２を設けてもよい。 In the ultrasonic densitometer 26 of the above-described embodiment, the transmission sensor 31 and the reception sensor 32 are provided at positions facing each other across the flow path of the tube main body 30, and the ultrasonic concentration meter 26 is super perpendicular to the direction in which the sludge W1 flows. Although the sound wave S1 is transmitted and received, the present invention is not limited to this. For example, the transmission sensor 31 and the reception sensor 32 may be provided so as to transmit and receive the ultrasonic wave S1 in parallel with the flow direction of the sludge W1. Moreover, you may provide the transmission sensor 31 and the reception sensor 32 so that the ultrasonic wave S1 may be transmitted / received in the state inclined with respect to the distribution direction of the sludge W1.
　・上記実施の形態の汚泥処理システム１では、最終沈殿槽５から汚泥Ｗ１を排出する配管２５において、曝気槽４に汚泥Ｗ１を返送する分岐部よりも下流側に超音波濃度計２６を設けていたが、その分岐部よりも上流側の配管や曝気槽４側の配管に超音波濃度計２６を設けてもよい。さらには、浮上濃縮槽１１と消化槽１２とを繋ぐ配管の途中などに超音波濃度計２６を設けてもよい。また、汚泥処理システム１では、２つの超音波濃度計２２，２６で測定した汚泥濃度に基づいて、消化槽１２における薬剤の投入量の調整等を行うものであったが、これに限定されるものではない。１つの超音波濃度計や３つ以上の複数の超音波濃度計で測定した汚泥濃度に基づいて、薬剤の投入量の調整等を行うように構成してもよい。 In the sludge treatment system 1 of the above embodiment, in the pipe 25 for discharging the sludge W1 from the final sedimentation tank 5, an ultrasonic densitometer 26 is provided on the downstream side of the branch part that returns the sludge W1 to the aeration tank 4. However, the ultrasonic densitometer 26 may be provided in a pipe on the upstream side of the branch portion or a pipe on the aeration tank 4 side. Furthermore, you may provide the ultrasonic concentration meter 26 in the middle of the piping which connects the floating concentration tank 11 and the digestion tank 12, etc. FIG. Moreover, in the sludge treatment system 1, although the adjustment of the input amount of the chemical in the digestion tank 12 is performed based on the sludge concentration measured by the two ultrasonic densitometers 22 and 26, it is limited to this. It is not a thing. You may comprise so that adjustment of the injection | throwing-in amount of a chemical | medical agent etc. may be performed based on the sludge density | concentration measured with one ultrasonic densitometer or three or more ultrasonic densitometers.
　・上記実施の形態の汚泥処理システム１において、超音波濃度計２２，２６で測定した汚泥濃度に基づいて、消化槽１２に投入する薬剤の投入量を調整したり、汚泥脱水機１３の稼働率を調整したりしていたが、これら以外の処理装置における処理条件を調整するように構成してもよい。具体的には、超音波濃度計２６で測定した汚泥濃度に基づいて、例えば汚泥焼却炉１４における火力の調整や造粉脱りん装置１５における薬剤の投入量の調整を行うように構成してもよい。 In the sludge treatment system 1 of the above-described embodiment, the amount of chemical to be fed into the digester 12 is adjusted based on the sludge concentration measured by the ultrasonic densitometers 22 and 26, or the operating rate of the sludge dehydrator 13 However, it may be configured to adjust processing conditions in processing apparatuses other than these. Specifically, based on the sludge concentration measured by the ultrasonic densitometer 26, for example, the thermal power adjustment in the sludge incinerator 14 or the chemical input amount in the powder dephosphorization apparatus 15 may be adjusted. Good.
　次に、特許請求の範囲に記載された技術的思想のほかに、前述した実施の形態によって把握される技術的思想を以下に列挙する。 Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiment described above are listed below.
　（１）請求項２または３において、前記超音波受信手段の受信信号を増幅して出力するとともに、信号増幅のゲインを調整可能な信号増幅手段をさらに備え、前記信号増幅手段は、前記第２の周波数の超音波を用いて演算した前記汚泥濃度の結果に基づき、前記第１の周波数に対応する前記信号増幅のゲインを自動的に調整することを特徴とする汚泥濃度測定用の超音波濃度計。 (1) In Claim 2 or 3, further comprising a signal amplifying means capable of amplifying and outputting a received signal of the ultrasonic receiving means and adjusting a gain of the signal amplification, wherein the signal amplifying means includes the second signal amplifying means. An ultrasonic concentration for measuring the sludge concentration, wherein the gain of the signal amplification corresponding to the first frequency is automatically adjusted based on the result of the sludge concentration calculated using the ultrasonic wave having the frequency of Total.
　（２）請求項２乃至８のいずれか１項において、前記第１の周波数及び前記第２の周波数の各超音波について、前記汚泥濃度に対する前記減衰量の変化量が直線的な関係を有する領域に、前記自動切換変移点に対応した設定濃度値が設定されることを特徴とする汚泥濃度測定用の超音波濃度計。 (2) In any one of claims 2 to 8, for each of the ultrasonic waves of the first frequency and the second frequency, a region where the amount of change in the attenuation with respect to the sludge concentration has a linear relationship Further, a set concentration value corresponding to the automatic switching transition point is set, and an ultrasonic densitometer for measuring sludge concentration.
　（３）請求項７において、前記被測定汚泥の温度を測定する温度測定手段を備え、前記設定濃度値変更手段は、前記温度測定手段の測定結果に基づいて、前記自動切換変移点に対応した設定濃度値を変更することを特徴とする汚泥濃度測定用の超音波濃度計。 (3) In Claim 7, the apparatus includes temperature measuring means for measuring the temperature of the sludge to be measured, and the set concentration value changing means corresponds to the automatic switching transition point based on the measurement result of the temperature measuring means. An ultrasonic densitometer for measuring sludge concentration, characterized by changing the set concentration value.
　（４）技術的思想（３）において、前記温度測定手段は、前記被測定汚泥を伝搬する超音波の伝搬時間に基づいて、前記温度を測定することを特徴とする汚泥濃度測定用の超音波濃度計。 (4) In the technical idea (3), the temperature measuring means measures the temperature based on the propagation time of the ultrasonic wave propagating through the measured sludge. Densitometer.
　（５）請求項７において、前記設定濃度値変更手段は、前記第１の周波数における特定の汚泥濃度での前記減衰量の変化率、及び、前記第２の周波数における前記特定の汚泥濃度での前記減衰量の変化率に基づいて、前記自動切換変移点に対応した設定濃度値を変更することを特徴とする汚泥濃度測定用の超音波濃度計。 (5) In claim 7, the set concentration value changing means is the rate of change of the attenuation amount at a specific sludge concentration at the first frequency, and the specific sludge concentration at the second frequency. An ultrasonic densitometer for sludge concentration measurement, wherein a set concentration value corresponding to the automatic switching transition point is changed based on a change rate of the attenuation amount.
　（６）請求項１乃至８のいずれか１項において、前記汚泥濃度を表示する表示装置を備えることを特徴とする汚泥濃度測定用の超音波濃度計。 (6) The ultrasonic densitometer for measuring the sludge concentration according to any one of claims 1 to 8, further comprising a display device that displays the sludge concentration.
　（７）請求項１乃至８のいずれか１項において、前記汚泥濃度を表示するとともに、前記汚泥濃度と前記超音波の減衰量との関係を示す線分を有するグラフを前記超音波の周波数毎に表示する表示装置を備えることを特徴とする汚泥濃度測定用の超音波濃度計。 (7) In any one of claims 1 to 8, a graph having a line segment indicating the relationship between the sludge concentration and the ultrasonic attenuation is displayed for each ultrasonic frequency. An ultrasonic densitometer for measuring the concentration of sludge, comprising a display device for displaying on the screen.
　（８）請求項１乃至８のいずれか１項において、前記汚泥濃度を表示するとともに、前記汚泥濃度と前記超音波の減衰量との関係を示す線分を有するグラフを前記超音波の周波数毎に表示し、かつ、前記グラフ中において前記周波数の自動切換変移点に対応した設定濃度値を示す直線を表示する表示装置を備えることを特徴とする汚泥濃度測定用の超音波濃度計。 (8) In any one of Claim 1 thru | or 8, while displaying the said sludge density | concentration, the graph which has the line segment which shows the relationship between the said sludge density | concentration and the attenuation amount of the said ultrasonic wave for every frequency of the said ultrasonic wave An ultrasonic densitometer for sludge concentration measurement, comprising: a display device for displaying a straight line indicating a set concentration value corresponding to the automatic switching transition point of the frequency in the graph.
　（９）請求項９または１０において、前記超音波濃度計を用いて測定した汚泥濃度が異常値になった場合に、システム異常である旨を通知する警報手段を備えたことを特徴とする汚泥処理システム。 (9) The sludge according to claim 9 or 10, further comprising alarm means for notifying that the system is abnormal when the sludge concentration measured using the ultrasonic densitometer becomes an abnormal value. Processing system.
　（１０）沈砂池、最初沈殿槽、曝気槽または密閉槽、最終沈殿槽の順に下水を流通させて水処理工程を行うとともに、複数種の処理装置からなる処理装置群を用いて汚泥処理工程を行う下水道施設の汚泥処理システムであって、前記最終沈殿槽から排出された汚泥を前記処理装置群に供給する配管の途中に設けられた請求項１乃至８のいずれか１項に記載の超音波濃度計と、前記超音波濃度計が測定した前記汚泥濃度に基づいて、前記処理装置における処理条件を調整する調整手段とを備えたことを特徴とする汚泥処理システム。 (10) A water treatment process is performed by circulating sewage in the order of a sand basin, an initial sedimentation tank, an aeration tank or a closed tank, and a final sedimentation tank, and a sludge treatment process is performed using a treatment apparatus group including a plurality of kinds of treatment apparatuses. The ultrasonic treatment according to any one of claims 1 to 8, wherein the ultrasonic treatment system is a sludge treatment system for a sewerage facility that is provided in the middle of a pipe that supplies the sludge discharged from the final sedimentation tank to the treatment device group. A sludge treatment system comprising: a densitometer; and an adjusting unit that adjusts a treatment condition in the treatment device based on the sludge concentration measured by the ultrasonic densitometer.
　１…汚泥処理システム
　２…沈砂池
　３…最初沈殿槽
　４…曝気槽
　５…最終沈殿槽
　１２…薬剤処理槽としての消化槽
　１３…汚泥脱水機
　１４…処理装置としての汚泥焼却炉
　１５…処理装置としての造粉脱りん装置
　２４…薬剤投入量調整手段としての薬剤投入装置
　２６…汚泥濃度測定用の超音波濃度計としての超音波濃度計
　３１…超音波送信手段としての送信センサ
　３２…超音波受信手段としての受信センサ
　３５…信号増幅手段としての信号増幅回路
　３６…濃度判定手段、測定用周波数切換手段及び設定濃度値変更手段としてのコントローラ
　Ｓ１…超音波
　Ｗ１…汚泥 DESCRIPTION OF SYMBOLS 1 ... Sludge processing system 2 ... Sedimentation basin 3 ... Initial sedimentation tank 4 ... Aeration tank 5 ... Final sedimentation tank 12 ... Digestion tank as a chemical treatment tank 13 ... Sludge dehydrator 14 ... Sludge incinerator 15 as a processing apparatus 15 ... Processing apparatus Powder dephosphorization device 24 as a medicine input device as a medicine input amount adjusting means 26 ... Ultrasonic concentration meter as an ultrasonic concentration meter for measuring sludge concentration 31 ... Transmission sensor as an ultrasonic transmission means 32 ... Ultrasonic Receiving sensor 35 as receiving means 35 ... Signal amplifying circuit as signal amplifying means 36 ... Controller as concentration determining means, measuring frequency switching means and set concentration value changing means S1 ... Ultrasonic wave W1 ... Sludge

Claims (10)

  1. 　被測定汚泥中に周波数の異なる超音波を発信可能な超音波送信手段と、前記被測定汚泥中を伝搬した前記超音波を受信する超音波受信手段とを備え、前記超音波の受信信号の強度から超音波減衰量を求め、前記超音波減衰量から前記被測定汚泥の汚泥濃度を演算する超音波濃度計であって、
    　前記汚泥濃度が前記周波数の自動切換変移点に対応した設定濃度値に到達したか否かを判定する濃度判定手段と、
    　前記設定濃度値に到達したと前記濃度判定手段が判断したときに、前記超音波送信手段が発信する前記超音波の周波数を別のものに自動的に切り換える測定用周波数切換手段と
    を備えたことを特徴とする汚泥濃度測定用の超音波濃度計。     An ultrasonic transmission means capable of transmitting ultrasonic waves having different frequencies in the measured sludge; and an ultrasonic receiving means for receiving the ultrasonic waves propagated in the measured sludge, the intensity of the received signal of the ultrasonic waves An ultrasonic densitometer that calculates an ultrasonic attenuation amount from the ultrasonic attenuation amount and calculates a sludge concentration of the measured sludge from the ultrasonic attenuation amount,
    A concentration determination means for determining whether the sludge concentration has reached a set concentration value corresponding to the automatic switching transition point of the frequency;
    A frequency switching unit for measurement that automatically switches the frequency of the ultrasonic wave transmitted from the ultrasonic wave transmission unit to another when the concentration determination unit determines that the set concentration value has been reached. Ultrasonic densitometer for measuring sludge concentration.
  2. 　前記測定用周波数切換手段は、低濃度域の測定に適した第１の周波数と、前記第１の周波数とは異なるものであって高濃度域の測定に適した第２の周波数との間で前記超音波の周波数の切換を行うとともに、
    　前記汚泥濃度が減少して高濃度側から前記設定濃度値に到達したと前記濃度判定手段が判断したときに、前記超音波の周波数を、前記第２の周波数から前記第１の周波数に自動的に切り換える一方、
    　前記汚泥濃度が増加して低濃度側から前記設定濃度値に到達したと前記濃度判定手段が判断したときに、前記超音波の周波数を、前記第１の周波数から前記第２の周波数に自動的に切り換える
    ことを特徴とする請求項１に記載の汚泥濃度測定用の超音波濃度計。     The frequency switching means for measurement is between a first frequency suitable for measurement in a low concentration region and a second frequency different from the first frequency and suitable for measurement in a high concentration region. While switching the frequency of the ultrasonic wave,
    The ultrasonic frequency is automatically changed from the second frequency to the first frequency when the concentration determination means determines that the sludge concentration has decreased and has reached the set concentration value from the high concentration side. While switching to
    The ultrasonic frequency is automatically changed from the first frequency to the second frequency when the concentration determination means determines that the sludge concentration has increased and has reached the set concentration value from the low concentration side. The ultrasonic densitometer for measuring the sludge concentration according to claim 1, wherein
  3. 　前記第１の周波数は、前記第２の周波数の３倍の周波数であることを特徴とする請求項２に記載の汚泥濃度測定用の超音波濃度計。 The ultrasonic densitometer for sludge concentration measurement according to claim 2, wherein the first frequency is three times the second frequency.
  4. 　前記超音波受信手段の受信信号を増幅して出力するとともに、信号増幅のゲインを調整可能な信号増幅手段をさらに備え、
    　前記信号増幅手段は、前記第１の周波数の超音波を用いて演算した前記汚泥濃度の結果に基づき、前記第２の周波数に対応する前記信号増幅のゲインを自動的に調整する
    ことを特徴とする請求項２または３に記載の汚泥濃度測定用の超音波濃度計。     Amplifying and outputting the received signal of the ultrasonic receiving means, and further comprising a signal amplifying means capable of adjusting a gain of signal amplification,
    The signal amplification means automatically adjusts the gain of the signal amplification corresponding to the second frequency based on the result of the sludge concentration calculated using the ultrasonic wave of the first frequency. The ultrasonic densitometer for sludge concentration measurement according to claim 2 or 3.
  5. 　前記超音波送信手段及びそれに対向して配置される前記超音波受信手段は複数対設けられるとともに、前記信号増幅手段は、前記超音波受信手段毎に信号増幅のゲインを調整することを特徴とする請求項４に記載の超音波濃度計。 A plurality of pairs of the ultrasonic transmission means and the ultrasonic reception means arranged opposite to the ultrasonic transmission means are provided, and the signal amplification means adjusts a gain of signal amplification for each of the ultrasonic reception means. The ultrasonic densitometer according to claim 4.
  6. 　前記測定用周波数切換手段は、前記信号増幅手段による前記ゲインの調整後に前記超音波の周波数の切換を行うことを特徴とする請求項４または５に記載の汚泥濃度測定用の超音波濃度計。 6. The ultrasonic densitometer for measuring a sludge concentration according to claim 4, wherein the frequency switching means for measurement switches the frequency of the ultrasonic wave after the gain is adjusted by the signal amplifying means.
  7. 　前記自動切換変移点に対応した設定濃度値を変更する設定濃度値変更手段をさらに備えたことを特徴とする請求項１乃至６のいずれか１項に記載の汚泥濃度測定用の超音波濃度計。 The ultrasonic concentration meter for sludge concentration measurement according to any one of claims 1 to 6, further comprising set concentration value changing means for changing a set concentration value corresponding to the automatic switching transition point. .
  8. 　前記設定濃度値変更手段は、前記信号増幅手段によって前記ゲインが低くなるように調整されたときに、前記設定濃度値を低濃度側に変更することを特徴とする請求項７に記載の汚泥濃度測定用の超音波濃度計。 The sludge concentration according to claim 7, wherein the set concentration value changing means changes the set concentration value to a low concentration side when the gain is adjusted by the signal amplifying means to be low. Ultrasonic densitometer for measurement.
  9. 　沈砂池と、最初沈殿槽と、曝気槽または密閉槽と、最終沈殿槽とを用いて水処理工程を行うとともに、薬剤処理槽を含む複数種の処理装置からなる処理装置群を用いて汚泥処理工程を行う下水道施設の汚泥処理システムであって、
    　前記最終沈殿槽から排出された汚泥を前記処理装置群に供給する配管の途中に設けられた請求項１乃至８のいずれか１項に記載の超音波濃度計と、
    　前記超音波濃度計が測定した前記汚泥濃度に基づいて、前記薬剤処理槽に投入する薬剤の投入量を調整する薬剤投入量調整手段と
    を備えたことを特徴とする汚泥処理システム。     A water treatment process is performed using a sand basin, an initial sedimentation tank, an aeration tank or a closed tank, and a final sedimentation tank, and sludge treatment is performed using a treatment apparatus group including a plurality of treatment apparatuses including a chemical treatment tank. A sludge treatment system for a sewerage facility that performs a process,
    The ultrasonic densitometer according to any one of claims 1 to 8, which is provided in the middle of a pipe for supplying the sludge discharged from the final sedimentation tank to the treatment device group,
    A sludge treatment system comprising: a chemical input amount adjusting means for adjusting an input amount of a chemical to be supplied to the chemical treatment tank based on the sludge concentration measured by the ultrasonic densitometer.
  10. 　前記処理装置群には汚泥脱水機が含まれ、前記超音波濃度計が測定した前記汚泥濃度に基づいて、前記汚泥脱水機の稼働率を調整することを特徴とする請求項９に記載の汚泥処理システム。 10. The sludge according to claim 9, wherein the treatment device group includes a sludge dewatering machine, and the operating rate of the sludge dewatering machine is adjusted based on the sludge concentration measured by the ultrasonic densitometer. Processing system.
PCT/JP2012/051897 2012-01-20 2012-01-20 Ultrasonic concentration meter for measuring sludge concentration, and sludge treatment system WO2013108413A1 (en)

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