JPS6319804B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for calibrating a flowmeter that uses a Doppler flowmeter to calibrate a flowmeter placed in a piping section that does not satisfy installation conditions.

Generally, flowmeters installed in a piping network meet predetermined installation conditions (distance from the flowmeter to valves, pumps, etc. installed upstream and downstream, straight length of piping before and after the flowmeter, etc.). Therefore, it is installed to ensure that there are no errors in the measurement of the flowmeter. However, in recent years,
In order to transport appropriate amounts of water, gas, etc., it is necessary to accurately understand the flow rate of fluid flowing through each part of the existing piping network, and it is also necessary to measure the flow rate of fluid flowing through piping parts that do not meet the above installation conditions. It may happen. Figures 1, 2, and 3 show the case where a flowmeter is installed near a curved pipe section where a straight pipe length that satisfies the installation conditions is not obtained. Figure 1 shows the curve of pipe 1. A case is shown in which a flowmeter 2 such as an insertion type electromagnetic flowmeter, a pitot tube type flowmeter, a Karman type flowmeter, a blade wheel type flowmeter, etc. is provided near the pipe portion 1a. FIG. 2 shows a case where an ultrasonic flow meter 4 is provided near the curved pipe portion 3a of the pipe 3. Further, FIG. 3 shows a case where a differential pressure output section 5b for obtaining a fluid pressure difference is provided near the curved pipe portion 5a of the pipe 5, and a differential pressure flowmeter is installed in this section 5b. However, in either case, the flowmeters 2, 4, and 6 are installed near the bent pipe sections 1a, 3a, and 5a, and it is not possible to obtain a straight pipe length that satisfies the installation conditions, making it impossible to accurately measure the flow rate. There is a problem. Therefore, it has been desired to accurately measure the flow rate by disposing a conventional flow meter in a piping section that does not meet the installation conditions.

The present invention has been made in consideration of the above circumstances, and provides calibration of a flowmeter that can accurately measure the flow rate of fluid flowing through a piping section even when the flowmeter is installed in a piping section that does not meet the installation conditions. The purpose is to provide a method.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 4 is a diagram for explaining the same embodiment, and shows a curved pipe portion 7a of the pipe 7 with a part cut away.
A vibration generator 8, an ultrasonic Doppler flowmeter 9 for measuring the absolute flow rate of a fluid, and a flowmeter to be calibrated 10 for measuring the flow rate of a fluid containing almost no foreign matter such as solid matter or bubbles are installed near the . ing. Note that the Doppler flowmeter 9 is detachably attached to the piping 7 during calibration. A fluid 11 containing almost no foreign matter such as solid matter or air bubbles is flowing in the pipe 7 in the direction indicated by the arrow, and foreign matter 12 is mixed into the fluid 11 by a foreign matter generation operation to be described later. In addition, a scale 13 is attached to the pipe wall of the pipe 7.
is attached. Note that the Doppler flowmeter 9
A sensor head 16 consisting of transmitting/receiving elements 14 and 15, a processing circuit 17 that processes the signal sent from the sensor head 16 to obtain the flow rate, and a not-shown circuit that displays the flow rate based on the signal sent from the processing circuit 17. The sensor head 16 is fixed to the piping 7 via a mounting member 18 during calibration, and is removed after calibration.

Note that an ultrasonic medium oscillator is used as the vibration generator 8 to separate the scale 13 adhering to the inner wall of the pipe into the fluid 11 and mix the foreign matter 12 therein.

In the above configuration, the flowmeter to be calibrated 10
At the time of calibration, the vibration generator 8 is operated, and the scale 13 adhering to the inner wall of the pipe 7 is separated into the fluid 11 and mixed in as foreign matter 12. Then, the foreign matter 12 is dispersed within the fluid 11 and flows through the pipe 7 at the same flow rate as the fluid 11, functioning as an indicator of the movement of the fluid 11. Next, an ultrasonic wave as a detection wave is transmitted to the fluid 11 from the transmitting element 14 of the sensor head 16, and the ultrasonic wave as a reflected wave reflected by the foreign object 12 in the fluid 11 is received by the receiving element 15. In the series of processes of transmission of ultrasonic waves, reflection by the moving foreign object 12, and reception as described above, the ultrasonic waves exhibit a Doppler effect with a frequency change depending on the flow velocity of the foreign object 12. Therefore, due to the change in the frequency of the ultrasonic waves, foreign particles 1
2, that is, the flow velocity of the fluid 11, can be used to measure the flow rate of the fluid 11.

The flow rate signal obtained by the sensor head 16 in this way is sent to the processing circuit 17.
The signal is processed by the system, and the absolute flow rate of the fluid is displayed on a display circuit (not shown). The flow meter 10 to be calibrated is calibrated based on the displayed absolute flow rate value of the fluid.

As described above, according to this embodiment, even if the flowmeter to be calibrated 10 is installed in the curved pipe section 7a that does not meet the installation conditions, it can be correctly calibrated using the fluid flow rate of the ultrasonic Doppler flowmeter 9. . Furthermore, since the Doppler flowmeter 9 is detachably attached to the piping 7 during calibration, it has the advantage that it can be removed after calibration and used for calibrating other flowmeters to be calibrated.

Note that the present invention is not limited to the one embodiment described above. For example, in the embodiment described above, the curved pipe section 7a was shown as a piping section that does not meet the installation conditions, but it can of course be applied to other piping sections that do not meet the installation conditions. Further, in the above embodiment, an ultrasonic medium oscillator is used as the vibration generator 8 to separate the scale 13 into the fluid and mix the foreign matter 12, but the following method may also be used. . First, as a method of mixing the foreign matter 12 without making a hole in the pipe as in the above embodiment, (a) hitting the pipe repeatedly with a powered hammer like a rock drill,
Alternatively, a method in which scale adhering to the inner wall of the pipe is peeled off into the fluid by an excitation method such as hammering by hand and foreign matter is mixed in, and (b) a strong ultrasonic oscillator is used as the vibration generator 8. There is a method in which air bubbles are generated in the piping and the bubbles are mixed in as foreign matter. In addition, as a method of making a hole in the pipe, (c) a method of making a small hole in the pipe and injecting foreign matter through this hole,
(iv) When the fluid is an electrically conductive liquid, there is a method in which a small hole is made in the pipe, an electrode is inserted, and electrolysis is performed inside the pipe to generate minute bubbles, which are then mixed in as foreign matter. As the foreign matter, scale or bubbles are used as described above, but other solids, gases, or liquids may also be used. That is, when the fluid is a liquid, a solid, a gas, or a liquid that has no affinity with the liquid as a fluid may be used, and when the fluid is a gas, a solid or a liquid may be used. Further, in the embodiment described above, the ultrasonic Doppler flowmeter 9 was used as the Doppler flowmeter, but a radio wave type or optical Doppler flowmeter may be used.

It goes without saying that various other modifications can be made without departing from the spirit of the invention.

As explained above, according to the present invention, a foreign substance is mixed into the fluid when calibrating the flowmeter to be calibrated, the flow rate of the fluid is obtained by the Doppler flowmeter based on the flow velocity of the foreign substance, and the flow rate of the fluid is obtained based on this flow rate. Since the flowmeter to be calibrated is calibrated, it is possible to provide a method for calibrating a flowmeter that can accurately measure the flow rate of fluid flowing through the piping even when the flowmeter is installed in a piping that does not meet the installation conditions.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are diagrams showing installation positions of flowmeters that require calibration depending on installation conditions, and FIG. 4 is a diagram for explaining one embodiment of the present invention. 2, 4, 6...Flowmeter, 7...Piping, 8...Vibration generator, 9...Ultrasonic Doppler flowmeter, 10
...Flowmeter to be calibrated, 11...Fluid, 12...Foreign object, 13...Scale, 14...Transmission element, 15
...Receiving element, 16...Sensor head, 17...
processing circuit.

Claims (1)

[Claims] 1. A flowmeter to be calibrated that measures the flow rate of the fluid is installed in a pipe that transports a fluid that contains almost no foreign matter, and when calibrating this flowmeter, foreign matter is mixed into the fluid and moved at the same flow rate as the fluid. , from a Doppler flowmeter detachably attached to piping near the flowmeter, a detection wave having a predetermined frequency is emitted to the foreign object to obtain a reflected wave, and a frequency difference between this reflected wave and the detection wave is determined. A method for calibrating a flowmeter, comprising: measuring the flow rate of the fluid, and calibrating the flowmeter to be calibrated based on the measured value.