JP3720299B2 - Ultrasonic sludge concentration measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic sludge concentration measuring apparatus for measuring the solid matter concentration in sludge at a water treatment facility or the like by utilizing the fact that the attenuation amount of ultrasonic waves has a correlation with the sludge concentration.
[0002]
[Prior art]
In conventional ultrasonic sludge concentration measurement devices, bubbles in sludge that have a large effect on sludge concentration measurement accuracy are reduced or eliminated by the pressure applied by the pressure defoaming device, and a single frequency is applied to the measured sludge. A correction circuit device (equipment) separately performs a correction operation on the ultrasonic attenuation obtained by irradiating ultrasonic waves, and the result is displayed as a measured sludge concentration value of the measured sludge.
[0003]
[Problems to be solved by the invention]
Since the conventional ultrasonic sludge concentration measuring apparatus is configured as described above, if bubbles are mixed in the sludge, the sludge concentration measurement value in which the attenuation amount of the ultrasonic wave is added by the amount affected by the bubbles. Therefore, there has been a problem that the sludge concentration measurement error becomes large. Therefore, when measuring the sludge concentration, the bubbles in the sludge are reduced or eliminated by the pressure applied by the pressure defoaming device. In this case, since the pressurization time is required, intermittent measurement is performed, and air bubbles are mixed in the sludge. However, there is a problem that the bubbles cannot be completely removed.
In addition, since correction calculation of ultrasonic attenuation amount by single-frequency ultrasonic irradiation to the sludge to be measured is performed by a separate correction circuit device, expensive devices and equipment are required, handling is complicated, and as a sludge concentration measurement device There was a problem that it would be a large facility. Furthermore, in order to transmit and receive ultrasonic waves having different frequencies, a wave transmitting unit and a wave receiving unit must be provided for each frequency, and there is a problem similar to the above.
[0004]
This invention was made in order to solve the above problems, and the sludge concentration of the measured sludge is determined from the plurality of ultrasonic attenuations obtained by irradiating the measured sludge with a plurality of ultrasonic waves having different frequencies. An object is to obtain an ultrasonic sludge concentration measuring device that can be directly calculated.
[0005]
Another object of the present invention is to provide an ultrasonic sludge concentration measuring apparatus that can perform an ultrasonic attenuation correction calculation without requiring an expensive apparatus or equipment, and that can be easily handled and reduced in cost. And
[0006]
[Means for Solving the Problems]
The ultrasonic sludge concentration measuring apparatus according to the present invention has an ultrasonic wave transmission unit and an ultrasonic wave reception unit, and determines the sludge concentration of the measured sludge by the attenuation amount of the ultrasonic wave transmitted to the measured sludge. in sonic sludge concentration measuring apparatus, and transmits an ultrasonic wave ultra odd multiples the switchable frequency switching means of the sound wave fundamental frequency frequencies and at least two types of frequencies transmitting the measured sludge to the measured sludge comprising a sludge concentration operation manual stage from the ultrasound attenuation obtained for calculating the sludge concentration in the measurement sludge, the ultrasonic wave transmitter, one of the ultrasonic wave transmitter for transmitting a plurality of ultrasonic waves of different frequencies The ultrasonic wave receiving unit is composed of one ultrasonic wave receiving unit that receives a plurality of ultrasonic waves having different frequencies .
[0008]
The sludge concentration calculating means of the ultrasonic sludge concentration measuring apparatus according to the present invention calculates the ultrasonic attenuation amount due to the bubbles contained in the measured sludge based on the ultrasonic attenuation amount of two kinds of frequencies transmitted to the measured sludge. It corrects and calculates the sludge concentration of the measured sludge.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below.
Embodiment 1 FIG.
FIG. 1 is a conceptual diagram of the solid matter concentration in sludge and the ultrasonic attenuation amount with respect to bubbles.
In the figure, f1 and f2 are two types of measurement frequencies (MHz) with different types of ultrasonic waves applied to the sludge to be measured, Mf1 and Mf2 are ultrasonic attenuation amounts (dB) at f1 and f2, and X is a solid concentration ( %), Y is the bubble amount (%), af1 and af2 are attenuation coefficients (dB /%) of the solid concentration, and bf1 and bf2 are bubble attenuation coefficients (dB /%).
[0010]
In general, the sludge concentration of the sludge to be measured and the amount of bubbles contained therein are proportional to the attenuation of the irradiated ultrasonic wave, so the following equations (1) and (2) hold.
Mf1 = af1 · X + bf1 · Y (1)
Mf2 = af2 · X + bf2 · Y (2)
[0011]
Here, Ka = af2 / af1, Kb = bf2 / bf1, and the following expression (3) is obtained from the above expressions (1) and (2).
X = (Mf2−Kb · Mf1) / [af1 · (Ka−Kb)] (3)
If the solid matter concentration attenuation coefficient and the bubble attenuation coefficient of each frequency are known from this equation (3), the sludge concentration free from the influence of bubbles can be measured from the measured value (attenuation amount).
Since the solid matter concentration attenuation coefficient and the bubble attenuation coefficient are values that vary depending on the measurement target, they are input as coefficients obtained in advance.
When measuring the sludge concentration of the measured sludge at three or more different frequencies, using the factors such as the viscosity of the measured sludge and the sludge particle size, which are proportional to the ultrasonic attenuation, a third or higher order is used. Concentration calculation is performed as an equation. Thereby, the sludge density | concentration of to-be-measured sludge with higher precision can be obtained.
[0012]
FIG. 2 is a block diagram showing an ultrasonic sludge concentration measuring apparatus according to Embodiment 1 of the present invention.
In the figure, 1 is a sludge pipe of a water treatment facility, 2 is an ultrasonic wave transmission section that transmits at least two types of ultrasonic waves having different frequencies with respect to the sludge in the sludge pipe 1, and 3 is an ultrasonic wave transmission thereof. An ultrasonic receiving unit 4 that receives at least two types of ultrasonic waves having different frequencies from the unit 2 through the sludge pipe 1 is an A / D converter that performs A / D conversion on an output signal from the ultrasonic receiving unit 3. A D conversion unit, 5 is a control unit that inputs a digital signal from the A / D conversion unit 4, 6 is a sludge concentration calculation unit that exchanges signals with the control unit 5, 7 is a synthesizer, 8 is a display unit, Reference numeral 9 denotes an output unit. Here, the equations (1) to (3) are set in the sludge concentration calculating means 6.
[0013]
Next, the operation will be described.
The fundamental frequency of the detector is 1 MHz, and a frequency switching command is sent from the sludge concentration calculation means 6 to the control means 5 so that it can be transmitted at an odd multiple of 1 MHz, 3 MHz, and 5 MHz. The ultrasonic wave transmission unit 2 is driven by inputting the signal to the ultrasonic wave transmission unit 2.
In this way, by setting the frequency to an odd multiple, the odd harmonic characteristics can be used, so that one transmission means and one reception means (one ultrasonic detector) can be used. The ultrasonic wave can be transmitted and received.
[0014]
Then, at least two types of ultrasonic waves having different frequencies are transmitted from the ultrasonic wave transmission unit 2 to the ultrasonic wave reception unit 3 through the sludge pipe 1. Thereby, the ultrasonic wave receiving unit 3 receives the transmitted wave having a different frequency of the ultrasonic wave propagated through the sludge in the sludge pipe 1 and sends it to the A / D conversion unit 4, and the voltage is processed by the control unit 5. The sludge concentration calculating means 6 receives the measured value data. In this sludge concentration calculation means 6, the bubble correction calculation by the above formulas (1) and (2) is performed based on the data of the two frequencies (optional selection), and the calculated value as a result is the operation display unit. 8 and output to the output unit 9.
[0015]
According to the first embodiment described above, switching measurement is performed at multiple frequencies (for example, at least two frequencies), and correction calculation is performed from the selected multiple frequency data, so that bubbles, particle size, viscosity, etc. in the sludge can be obtained. There is an effect that an accurate sludge concentration can be measured without being affected.
In addition, it is possible to perform correction calculation of sludge measurement error factors by transmitting and receiving ultrasonic waves of different frequencies with one detector, and therefore, an inexpensive sludge concentration measuring device with a simple structure and high reliability can be obtained. There is an effect that it can be provided.
[0016]
Incidentally, ultrasonic switching means described in the first embodiment is not limited as long as a control means for controlling the ultrasonic transmitting means in response to the command structure and the instruction to transmit the ultrasonic waves having different frequencies .
[0017]
Embodiment 2. FIG.
FIG. 3 is a block diagram showing an ultrasonic sludge concentration measuring apparatus to which a pressure defoaming apparatus according to Embodiment 2 of the present invention is added. The same components as those in FIG. Is omitted.
In the figure, 10 is a pressure defoaming operation circuit for inputting an output signal from the sludge concentration calculating means 6, and 11 is disposed between the ultrasonic wave transmitting unit 2 and the ultrasonic wave receiving unit 3, and It is a pressure defoaming device that inputs a signal from the foam operation circuit 10.
[0018]
According to the second embodiment, it is possible to switch between a pressure defoaming mode based on the amount of bubbles and a correction calculation measurement mode that is a mode for removing a sludge concentration measurement error factor. In this manual mode, each coefficient of bubble calculation can be obtained from the data before and after pressurization and stored. In addition, there is an effect that automatic operation combining the above measurement modes is also possible. Furthermore, even when air bubbles in the sludge to be measured are significant, by combining with the pressure defoaming device 11, the sludge measurement error is reduced, and the sludge concentration of the sludge to be measured can be continuously measured. .
[0019]
【The invention's effect】
As described above, according to the present invention, an ultrasonic method has an ultrasonic wave transmission unit and an ultrasonic wave reception unit, and obtains the sludge concentration of the measured sludge by the attenuation amount of the ultrasonic wave transmitted to the measured sludge. in the sludge concentration measuring device, obtained by transmitting an odd multiple to switchable frequency switching means and at least two of the measured sludge ultrasonic frequency of the ultrasonic frequency to the fundamental frequency of transmitting to the measured sludge comprising a sludge concentration calculation means to calculating the sludge concentration in the measurement sludge from the ultrasound attenuation, the ultrasonic wave transmitter is made one ultrasonic wave transmitter whose frequency is transmitting a different ultrasound Since the ultrasonic wave receiving unit is configured to include a single ultrasonic wave receiving unit that receives a plurality of ultrasonic waves having different frequencies, a plurality of ultrasonic waves having different frequencies irradiated from the ultrasonic wave transmitting unit are provided. The ultrasonic wave is transmitted through the sludge to be measured. By detecting the difference in ultrasonic attenuation due to the difference in the frequency at which the measured sludge propagates, it is possible to apply pressure based on the conventional method simply by performing calculations based on the ultrasonic attenuation that differs depending on the frequency. There is an effect that the sludge concentration of the sludge to be measured can be directly measured without the need for a defoaming device, and the equipment can be simplified and the cost can be reduced.
[0020]
In particular, in the present invention , as described above, one ultrasonic transmission unit and one ultrasonic reception unit capable of transmitting and receiving a plurality of ultrasonic waves having different frequencies are used, and are also transmitted to the sludge to be measured. by was switchable configuration odd multiples of the fundamental frequency the frequency of the ultrasonic wave to be waves, can be utilized odd harmonic characteristics Rutotomoni, as described above, each one ultrasonic wave transmitter and a plurality of ultrasonic waves different frequencies in the ultrasonic wave receiving unit can be transmitted and received waves, since it does not require a conventional such pressurized圧消bubble device, compact and easy maintenance sludge concentration measuring device This has the effect of simplifying the equipment and reducing costs.
[0021]
According to this invention, the sludge concentration calculating means corrects the ultrasonic attenuation amount due to the bubbles contained in the measured sludge based on the ultrasonic attenuation amount of at least two kinds of frequencies transmitted to the measured sludge. Since it is configured to calculate the sludge concentration of the sludge, ultrasonic attenuation by bubbles in the measured sludge, which is a measurement error factor of the sludge concentration of the measured sludge without requiring an expensive and large-scale pressurized defoaming device The amount can be corrected, and the correction can provide a sludge concentration measurement value with high measurement accuracy.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a solid matter concentration in sludge and an ultrasonic attenuation amount with respect to bubbles.
FIG. 2 is a block diagram showing an ultrasonic sludge concentration measuring apparatus according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram showing an ultrasonic sludge concentration measuring apparatus to which a pressure defoaming apparatus according to Embodiment 2 of the present invention is added.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sludge piping 2 Ultrasonic wave transmission part 3 Ultrasonic wave reception part 4 A / D conversion part 5 Control means 6 Sludge density | concentration calculation means 7 Synthesizer 8 Display part 9 Output part 10 Pressurization defoaming operation circuit 11 Pressure defoaming apparatus

Claims (2)

In an ultrasonic sludge concentration measuring device that has an ultrasonic wave transmission unit and an ultrasonic wave reception unit and obtains the sludge concentration of the measured sludge by the attenuation amount of the ultrasonic wave transmitted to the measured sludge,
The frequency switching means that can switch the frequency of the ultrasonic wave transmitted to the measured sludge to an odd multiple of the fundamental frequency and the ultrasonic attenuation obtained by transmitting the ultrasonic waves of at least two frequencies to the measured sludge comprising a sludge concentration calculation means to calculating the sludge concentration in the measurement sludge, the ultrasonic wave transmitter is one of an ultrasonic wave transmitter for transmitting a plurality of ultrasonic waves of different frequencies, the ultrasonic wave receiving The ultrasonic sludge concentration measuring device is characterized in that the unit is one ultrasonic wave receiving unit that receives a plurality of ultrasonic waves having different frequencies . The sludge concentration calculation means calculates the sludge concentration of the measured sludge by correcting the ultrasonic attenuation due to the bubbles contained in the measured sludge based on the ultrasonic attenuation amount of two kinds of frequencies transmitted to the measured sludge. ultrasonic sludge concentration measuring apparatus according to claim 1 Symbol mounting characterized in that it is a computing means.

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