JP4004935B2 - Processed water flow measurement system for sewerage plant - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an exterior type flow rate measurement that detects the flow rate of treated water such as domestic wastewater and human urine water from outside a pipe using ultrasonic waves in a sewerage plant.
[0002]
[Prior art]
There are two types of methods, a time difference type and a Doppler type, in which an ultrasonic wave receiving / transmitting head is provided outside the pipe and the flow rates of various fluids are measured. Since the measurement principle of the flow rate measurement by these is well known, the technical explanation is omitted.
Next, the advantages and problems of the time difference type ultrasonic flowmeter and the Doppler type ultrasonic flowmeter will be described.
Since the time difference formula is a method for measuring the flow velocity distribution in the entire pipe, it has an advantage that the flow rate can be measured with high accuracy. However, if a large amount of substances that inhibit the transmission of ultrasonic waves, such as bubbles and sludge, is mixed in the treated water, not only will the measurement accuracy be deteriorated, but the flow measurement may be impossible (missed). .
The Doppler method is a method that uses reflection of ultrasonic waves. Therefore, even when a large amount of ultrasonic transmitting material that cannot be measured by the time difference method described above is mixed, the missing measurement does not occur. Have. However, if the substance that reflects ultrasonic waves is not mixed in the fluid to be measured, it may be missed, and the place where the mixed substance is close to the sensor attached to the pipe, that is, the place near the outer diameter of the pipe. In the case where the flow is offset, the flow rate can be measured only in the vicinity of the sensor installation location, so the average flow rate in the entire pipe cannot be known, and the accuracy is poor compared to the time difference formula. Have.
[0003]
Sewerage plants usually cannot be shut down due to their social mission. Therefore, an external ultrasonic flowmeter that can be maintained without stopping operation is heavily used. Since the amount of treated water to be measured is a basic object of plant control, accuracy is also required. Therefore, although the time difference type flow meter is applied to almost all sewerage plants, on the other hand, the missing measurement which is the disadvantage described above often occurs, and the flow measurement accuracy is inferior to compensate for this. In many cases, the Doppler type is used. Thus, in order to measure the flow rate with high accuracy and no missing measurement for sewerage plants, two types are installed to take advantage of both the time difference method and the Doppler method, and switch according to the state of the treated water. It is efficient to use.
[0004]
From this point of view, when a plurality of sensors are connected in a pipe shape in a pipe and one sensor falls into a state that is difficult to measure for some reason, the situation is detected and complemented by other sensors. (See, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-7-110246 (5th page, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, in the prior art disclosed in Patent Document 1, since a sensor for measuring the flow rate is provided in the pipe, for example, when one sensor becomes unable to measure the flow rate for some reason, the cause is unknown. If the sensor is not restored, it is necessary to remove the entire sensor from the pipe, and there is a problem that the flow rate of the treated water cannot be measured during the maintenance period and the plant is stopped.
The present invention has been made to solve the above-described problems, and is not missing even when the mixing of ultrasonic permeation-inhibiting substances increases in the treated water, is easy to maintain, and stops plant operation. It aims at providing the treated water measuring system of a sewerage plant which does not need to be made to do.
[0007]
[Means for Solving the Problems]
A process water flow measurement system for a sewer plant equipped with a time difference type ultrasonic flow meter and a Doppler type ultrasonic flow meter,
Each of the flow meters is composed of a respective ultrasonic transmission / reception head unit and a signal converter,
The ultrasonic wave receiving / transmitting head part is provided outside the treated water piping, the signal converter is provided with a flow rate alarm setting unit, and the flow rate alarm setting unit has a threshold value of the treated water flow rate. Is set, and when the treated water flow rate is equal to or lower than the threshold value, the flow rate measurement by the time difference type ultrasonic flow meter is performed. The flow rate alarm setting unit performs switching.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a treated water flow rate measurement system 100 of a sewer plant using ultrasonic waves according to the first embodiment. Fig. (A) is a perspective view of the piping section, Fig. (B) is a side view thereof, and Fig. (C) is a perspective view of the converter. In the figure, outside of the sewage sludge pipe 1 through which treated water flows, time difference type ultrasonic wave receiving / transmitting head portions 2a, 2b and Doppler type ultrasonic wave receiving / transmitting head portions 3a, 3b are attached by a fixing band 4. Yes.
Ultrasonic signals from the transmission / reception head units 2a, 2b, 3a, 3b are transmitted to the converter 6 via the dedicated cable 5. FIG. 2 is a diagram showing the logic in the converter 6, in which flow rate conversion units 7 a and 7 b, flow rate alarm setting units 8 a and 8 b, and an analog conversion unit 9 are provided. Here, a time difference type ultrasonic flowmeter 200 is connected to the flow rate conversion unit 7a, the flow rate alarm setting unit 8a, and the analog converter 9 that receive signals from the time difference type ultrasonic wave transmission / reception heads 2a and 2b. The Doppler type ultrasonic flowmeter 300 is composed of a second circuit connected to the Doppler type ultrasonic wave receiving / transmitting heads 3a and 3b, the flow rate conversion unit 7b, the flow rate alarm setting unit 8b, and the analog converter 9.
[0009]
Next, the operation will be described.
In the previous stage where the treated water flow rate measuring system 100 is provided, a sludge pond for temporarily storing sludge water to be treated is provided. The sludge pond has a capacity capable of accommodating the increase in the amount of sludge water while flowing into the sludge pond through the city piping.
Inside the pipe 1 provided on the lower side of the sludge pond, the treated water flows in a state of filling the inside thereof, and also includes bubbles generated in the sludge pond together with various filths. When such treated water passes through the time difference type ultrasonic wave receiving / transmitting head portions 2a, 2b and the Doppler type ultrasonic wave receiving / transmitting head portions 3a, 3b provided outside the pipe 1, the head portions 2a, 2b. , 3a, 3b are transmitted by the dedicated cable 5 and input to the converter 6. The signals are converted through the flow rate conversion unit 7a or 7b for the time difference type or Doppler type, respectively, and further converted into general industrial signals by the analog conversion unit 9 through the flow rate alarm setting unit 8a or 8b. It is converted and transmitted as flow rate information to the upper system of the sewerage plant control.
[0010]
In the first embodiment, the flow rate alarm setting units 8a and 8b include the time difference type ultrasonic flow rate corresponding to the treated water conditions of the plant, that is, the amount and size of sludge, the amount of bubbles generated in the sludge pond, and the like. A threshold value of the treated water flow rate to be switched between the flow rate measurement by the meter 200 and the flow rate measurement by the Doppler ultrasonic flow meter 300 is set. The reason for setting this threshold value is based on the idea of making use of the advantages of the flow rate measurement by the time difference type ultrasonic flow meter 200 and the Doppler type ultrasonic flow meter 300.
That is, the flow rate measurement by the time difference type ultrasonic flowmeter 200 is provided with receiving / transmitting heads 2a and 2b outside the pipe 1, and measures the flow rate of the treated water flowing in the pipe 1 so that the flow rate can be measured. It is desirable to measure the flow rate with the time difference type ultrasonic flowmeter 200 as much as possible because it can be performed with high accuracy. However, the flow rate measurement by the time difference type ultrasonic flowmeter 200 causes missing measurement when a large amount of bubbles, sludge, etc., which are substances that inhibit ultrasonic transmission, are mixed in the treated water. The ultrasonic transmission inhibiting substance is predominantly bubbles in the treated water, and the amount of bubbles varies depending on the plant depending on various factors such as plant installation conditions and changes in the amount of treated water over time. In the first embodiment, a flow rate upper limit value that can be measured by the time difference type ultrasonic flowmeter 200 is determined as a unique value in a plant in which the system is installed, and the flow rate alarm setting unit is set with this value as a threshold value. Set to 8a, 8b. When the amount of treated water exceeds the threshold value, the flow rate measurement by the Doppler type ultrasonic flow meter 300 is switched to compensate for the disadvantage of the time difference type ultrasonic flow meter 200.
[0011]
That is, a threshold value determined for each plant is provided in the flow rate alarm setting units 8a and 8b, and when the amount of treated water is equal to or less than the threshold value, the flow rate alarm setting unit 8a performs the time difference type ultrasonic transmission / reception head. The signals from the units 2a and 2b are measured so that the flow rate of the treated water is measured by the first circuit passing through the flow rate conversion unit 7a, the flow rate alarm setting unit 8a, and the analog conversion unit 9, that is, the time difference type ultrasonic flowmeter 200. When the threshold value is exceeded, the flow rate alarm setting unit 8a receives a signal from the Doppler type ultrasonic wave transmission / reception head units 3a, 3b through the second flow rate conversion unit 7b, the flow rate alarm setting unit 8b, and the analog conversion unit 9. The circuit is switched to measure the flow rate of the treated water by the Doppler type ultrasonic flowmeter 300. In this state, when the flow rate becomes equal to or lower than the threshold value, the flow rate alarm setting unit 8b similarly switches to perform the flow rate measurement by the first circuit, that is, the time difference type ultrasonic flowmeter 200.
Note that the threshold value can be measured before the time difference ultrasonic flowmeter 200 causes a missing measurement due to the water treatment conditions of the plant after the flowmeters 200 and 300 are installed in the plant, for example, sludge and bubble amount. The upper limit of the flow rate value is determined, and this value is changed with a significant change in the plant water treatment conditions.
[0012]
As described above, in the first embodiment, the exterior type time difference type ultrasonic flowmeter 200 and the Doppler type ultrasonic flowmeter 300 are provided, and at a predetermined threshold value determined in accordance with the treated water conditions of the plant. Since the flow rate is measured by switching the flowmeters 200 and 300, there is no missing measurement, and it is possible to follow a change in water treatment conditions, and it is easy to maintain and does not bring down the plant during maintenance. Can be provided.
[0013]
Embodiment 2. FIG.
In the first embodiment, the switching between the time difference type ultrasonic flow meter 200 and the Doppler type ultrasonic flow meter 300 is performed by the flow rate alarm setting units 8a and 8b with the treated water flow rate threshold value. In the second embodiment, as shown in FIG. 3, ultrasonic reception intensity alarm setting units 10a and 10b are provided on the input side of the flow rate conversion units 7a and 7b in the signal converter 6.
The first circuit connected to the ultrasonic wave reception intensity alarm setting unit 10a, the flow rate conversion unit 7a, and the analog converter 9 that receive signals from the time difference type ultrasonic wave transmission / reception head units 2a and 2b shown in FIG. Therefore, a time difference type ultrasonic flowmeter 200a is formed, and a second circuit connected to the Doppler type ultrasonic wave transmission / reception head units 3a and 3b, an ultrasonic wave reception intensity alarm setting unit 10b, a flow rate conversion unit 7b, and an analog converter 9 is used. Thus, a Doppler type ultrasonic flowmeter 300a is formed.
[0014]
Next, the operation will be described.
In the ultrasonic wave reception intensity alarm setting units 10a and 10b, a threshold value of ultrasonic wave reception intensity corresponding to the treated water condition of the plant, that is, the amount and size of sludge and the amount of bubbles contained in the treated water is set. For example, when the amount of bubbles contained in the treated water increases when the treated water flow rate is measured by the first circuit, that is, the time difference type ultrasonic flowmeter 200a, the ultrasonic reception intensity gradually decreases, When the threshold value is reached, the ultrasonic wave reception intensity alarm setting unit 10a switches to perform flow rate measurement with the second circuit, that is, the Doppler ultrasonic flow meter 300a. When the flow rate measurement is performed in this state and the amount of bubbles contained in the treated water decreases and reaches the threshold value, the ultrasonic reception intensity alarm setting unit 10b sets the first circuit, that is, It switches so that flow measurement may be performed with the time difference type ultrasonic flowmeter 200a.
The threshold value is determined according to the water treatment conditions of the plant after the flow meters 200a and 300a are installed in the plant, as in the first embodiment, and is a value according to a significant state change of the water treatment conditions. Is to be changed.
As described above, in the second embodiment, the ultrasonic wave reception intensity threshold value is set in the ultrasonic wave reception intensity alarm setting units 10a and 10b, and the flowmeter is switched using the threshold value as a boundary. Regardless of the water conditions, we can measure the flow rate without missing and provide a flow rate measurement system that is easy to maintain.
[0015]
Embodiment 3 FIG.
In the third embodiment, in place of the ultrasonic wave reception intensity alarm setting units 10a and 10b of the second embodiment, the ultrasonic wave velocity alarm setting units 11a and 11b are provided in the signal conversion unit 6 as shown in FIG. It is a configuration. The time difference type ultrasonic flowmeter 200b is formed by a first circuit connected to the time difference type ultrasonic wave receiving / transmitting head units 2a and 2b, the ultrasonic wave propagation speed alarm setting unit 11a, the flow rate conversion unit 7a, and the analog converter 9. The Doppler ultrasonic flowmeter 300b is constituted by a second circuit connected to the Doppler ultrasonic wave receiving / transmitting head units 3a and 3b, the ultrasonic wave propagation speed alarm setting unit 11b, the flow rate conversion unit 7b, and the analog converter 9. .
[0016]
Next, the operation will be described.
In the ultrasonic wave propagation speed alarm setting units 11a and 11b, similarly to the second embodiment, a threshold value of ultrasonic wave propagation speed corresponding to the treated water condition of the plant is set. Further, for example, when the treated water flow rate is measured by the first circuit, that is, the time difference type ultrasonic flowmeter 200b, the amount of bubbles and sludge contained in the treated water changes, and the ultrasonic propagation velocity is When the threshold value is reached, the ultrasonic wave propagation speed alarm setting unit 11a switches to the measurement by the second circuit, that is, the Doppler ultrasonic flow meter 300b. When the measurement in this state is performed and the amount of bubbles contained in the treated water changes again and reaches the threshold value, the ultrasonic wave propagation speed alarm setting unit 11b performs the first circuit, that is, the time difference type ultrasonic wave. Switch to flow measurement with the flow meter 200b.
As in the first embodiment, the threshold value is determined by the water treatment conditions of the plant after the flow meters 200b and 300b are installed in the plant, and the value is greatly increased as the water treatment conditions change. It will be changed.
As described above, in the third embodiment, the ultrasonic wave propagation speed threshold value is set in the ultrasonic wave propagation speed alarm setting units 11a and 11b, and the flowmeter is switched using this threshold value as a boundary. Regardless of the water conditions, we can measure the flow rate without missing and provide a flow rate measurement system that is easy to maintain.
[0017]
Embodiment 4 FIG.
In the first to third embodiments, an example in which the ultrasonic transmission / reception head units are provided with the time difference type 2a and 2b and the Doppler type 3a and 3b, respectively, is shown. As shown in FIG. 5, since the ultrasonic wave receiving / transmitting head portion 2c that can be used for both the time difference type and the Doppler type is provided, the number of sets of the receiving / transmitting heads is reduced and the system becomes inexpensive. 1 to the same effect as the third embodiment. In FIG. 5, the entry of the signal converter 6 is omitted.
[0018]
【The invention's effect】
Since the present invention is a treated water measuring system for a sewer plant having the above-described configuration, the following effects can be obtained.
It is equipped with a time difference type ultrasonic flow meter and a Doppler type ultrasonic flow meter, each flow meter is composed of a respective ultrasonic receiving / transmitting head part and a signal converter,
The ultrasonic transmission / reception head unit is provided outside the treated water piping, the signal converter is provided with a flow rate alarm setting unit, and a threshold value for the treated water flow rate is set in the flow rate alarm setting unit. The flow rate alarm setting unit switches so that the flow rate measurement using the time difference type ultrasonic flow meter is performed when the treated water flow rate is lower than the threshold value, and the flow rate measurement is performed using the Doppler ultrasonic flow meter when the treated water flow rate is higher than the threshold value. Therefore, even if there is an increase in the amount of substances that inhibit ultrasonic transmission due to bubbles, sludge, etc. in the treated water, there will be no situation that the flow measurement becomes impossible, and it will respond to changes in the water treatment conditions of the plant. In addition, it is possible to set the threshold value, and further, the maintenance is easy, and there is an excellent effect that the plant does not need to be stopped for the maintenance.
[Brief description of the drawings]
FIG. 1 is a diagram showing a treated water flow rate measurement system for a sewer plant according to Embodiments 1 and 2 of the present invention.
FIG. 2 is a diagram showing logic in a converter according to Embodiment 1 of the present invention.
FIG. 3 is a diagram showing logic in a converter according to a second embodiment of the present invention.
FIG. 4 is a diagram showing logic in a converter according to Embodiment 3 of the present invention.
FIG. 5 is a diagram showing a treated water flow rate measurement system for a sewer plant according to Embodiment 4 of the present invention.
[Explanation of symbols]
1 piping, 2a, 2b time difference type ultrasonic wave receiving / transmitting head,
2c Ultrasonic receiving / transmitting head,
3a, 3b Doppler type ultrasonic transmission / reception head, 6 signal converter,
7a, 7b Flow rate conversion unit, 8a, 8b Flow rate alarm setting unit, 9 Analog conversion unit,
10a, 10b Ultrasonic wave reception intensity alarm setting unit,
11a, 11b ultrasonic wave propagation speed alarm setting unit,
100 treated water flow measurement system,
200, 200a, 200b Time difference type ultrasonic flowmeter,
300, 300a, 300b Doppler type ultrasonic flowmeter.

Claims (3)

A process water flow measurement system for a sewer plant equipped with a time difference type ultrasonic flow meter and a Doppler type ultrasonic flow meter,
Each of the flow meters is composed of a respective ultrasonic transmission / reception head unit and a signal converter,
The ultrasonic wave receiving / transmitting head part is provided outside the treated water piping, the signal converter is provided with a flow rate alarm setting unit, and the flow rate alarm setting unit has a threshold value of the treated water flow rate. Is set, and when the treated water flow rate is equal to or lower than the threshold value, the flow rate measurement by the time difference type ultrasonic flow meter is performed. A system for measuring the flow rate of treated water in a sewage plant, wherein a flow rate alarm setting unit performs switching. The treated water measuring system for a sewage plant according to claim 1, wherein the ultrasonic wave receiving / transmitting head unit is provided so as to share the time difference type flow meter and the Doppler type flow meter. The said threshold value is set according to the treated water conditions after installing the said time difference type flow meter and the Doppler type flow meter in the said plant , The Claim 1 and Claim 2 characterized by the above-mentioned. The treated water measuring system of the sewer plant of any one of.

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