JPH07139982A - Ultrasonic flowmeter - Google Patents

Abstract

PURPOSE:To achieve a device eliminating the need for mounting a temperature sensor such as a thermistor to a piping and a device for processing the output signal. CONSTITUTION:A propagation time difference measurement means 8 where the transmission and reception points of ultrasonic waves 4 and 5 which are propagated in a fluid by an ultrasonic flowmeter sensor 1 at an upstream side and an ultrasonic flowmeter sensor 2 at a downstream side outputs a propagation time difference and a piping temperature calculation means 7 where the transmission and reception points of surface waves 13 and 14 propagated in a piping 3 outputs the temperature of fluid. After flow-rate and flow calculation means 9 and 10 where the propagation time difference of the ultrasonic waves 4 and 5 and the temperature of fluid are input obtain the flow rate of fluid which is temperature-compensated, the flow of the fluid is calculated, thus eliminating the need for a temperature sensor, reducing the space for mounting sensor of the piping 3, and at the same time simplifying the output processing device of the sensor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow meter for measuring the flow rate of fluid flowing in high temperature piping.

[0002]

2. Description of the Related Art As shown in FIG. 5, an ultrasonic flowmeter for measuring the flow rate of a fluid in a conventional pipe has an upstream ultrasonic flowmeter sensor 1 with a thermistor 11 arranged in a pipe 3 and a downstream flowmeter. The side ultrasonic flowmeter sensor 2, the propagation time difference measuring unit 8 to which the sensors 1 and 2 are connected, the thermistor thermometer 12 to which the thermistor 11 is connected, and the thermometer 12 are connected via the correction calculating unit 9. The flow rate calculation and display unit 10 was used.

In the above, the thermistor 11 connected to the thermistor thermometer 12 is provided in the pipe. Since the ultrasonic wave propagation velocity changes depending on the temperature of the fluid, the flow velocity is calculated by correcting the flow velocity due to the temperature. This is because it is necessary.

[0004]

In the conventional ultrasonic flowmeter, a thermistor or the like for temperature measurement must be provided in addition to the upstream ultrasonic sensor and the downstream ultrasonic sensor for measuring the flow velocity as described above. I had to do it. Therefore, a large space for mounting the sensor on the pipe is required,
There is also a problem that a processing circuit different from the ultrasonic signal processing is required. The present invention is intended to solve the above problems.

[0005]

An ultrasonic flowmeter according to the present invention comprises two ultrasonic flowmeter sensors, which are provided on the surface of a pipe through which a fluid flows and which are installed at intervals in the flow direction of the fluid. Of the two ultrasonic flowmeter sensors, the time period during which the ultrasonic wave generated from the ultrasonic flowmeter sensor located upstream of the fluid inside the pipe propagates to the ultrasonic flowmeter sensor located downstream Propagation time difference measuring means for measuring the difference between the time when ultrasonic waves emitted from the ultrasonic flowmeter sensor on the downstream side into the pipe propagate to the ultrasonic flowmeter sensor on the upstream side, and the two ultrasonic flowmeters. A means for calculating the temperature of the pipe from the time when the ultrasonic wave propagates on the surface of the pipe between the sensors, and a means for calculating the flow velocity and flow rate of the fluid flowing in the pipe from the propagation time difference and the pipe temperature. I am trying.

[0006]

In the above, the upstream ultrasonic flowmeter sensor and the downstream ultrasonic flowmeter sensor respectively emit and receive ultrasonic waves propagating in the fluid flowing in the pipe and ultrasonic waves propagating in the pipe itself. The time of transmitting / receiving ultrasonic waves propagating in the fluid is input to the propagation time difference measuring means, and the time of transmitting / receiving ultrasonic waves propagating in the pipe is input to the means for calculating the temperature of the pipe.

The propagation time difference measuring means to which the time point of transmission / reception of the ultrasonic beam is input is transmitted from the ultrasonic flow meter sensor on the upstream side, propagates in the fluid, and is received by the ultrasonic flow meter sensor on the downstream side. After obtaining the propagation time of the ultrasonic wave, and the propagation time of the ultrasonic wave that is transmitted from the ultrasonic flow meter sensor on the downstream side and propagates in the fluid and is received by the ultrasonic flow meter sensor on the upstream side, Calculate and output the propagation time difference.

The propagation time difference output from the propagation time difference measuring means is input to the means for calculating the flow velocity and the flow rate, and the flow velocity and flow rate calculating means first obtains the flow velocity of the fluid from the propagation time difference. It should be noted that this flow velocity contains an error due to temperature because the propagation time of the ultrasonic beam varies depending on the temperature change of the fluid.

On the other hand, the above-mentioned pipe temperature calculation means, which inputs the time of transmitting and receiving the ultrasonic wave propagating through the pipe, transmits the ultrasonic wave propagating through the pipe between the upstream ultrasonic flowmeter sensor and the downstream flowmeter ultrasonic sensor. The propagation time of the sound wave is calculated, and the propagation speed of this ultrasonic wave is calculated.

There is a constant relationship between the propagation velocity of ultrasonic waves and the temperature of the medium in which the ultrasonic waves propagate, and from the propagation velocity of ultrasonic waves to the temperature of the pipe (this is approximately equal to the temperature of the fluid inside). ) Can be obtained, the pipe temperature calculation means obtains the temperature of the fluid from the propagation velocity of the ultrasonic waves propagating through the pipe by utilizing the above relationship, and inputs the temperature to the flow velocity and flow rate calculation means.

The flow velocity and flow rate calculating means, which inputs the temperature of the fluid, corrects the flow velocity of the fluid including the error due to the temperature by using this, and then calculates the flow rate of the fluid using the corrected flow velocity of the fluid. To do.

As described above, the flow velocity of the fluid including the error due to the temperature, which is obtained from the propagation time difference of the ultrasonic waves propagating in the fluid, can be corrected by the temperature obtained from the propagation time of the ultrasonic wave propagating in the pipe. Therefore, the temperature sensor used in the conventional device becomes unnecessary, the sensor mounting space of the pipe can be reduced, and the output processing device of the sensor can be simplified.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In FIG. 1, reference numerals 1 and 2 denote an upstream ultrasonic flowmeter sensor and a downstream ultrasonic flowmeter sensor, respectively, which are arranged in a pipe 3 through which a fluid flows. 5, and ultrasonic waves (surface waves) for temperature measurement
It sends and receives 13,14.

Reference numeral 6 denotes an ultrasonic flow meter processing circuit section for inputting respective output signals from the sensors 1 and 2, which is provided with a temperature calculation section 7 and a propagation time difference measuring section 8 for obtaining a propagation time difference (ΔT).

Reference numeral 9 denotes a correction calculation unit which calculates the flow velocity of the fluid from the propagation time calculated by the propagation time difference measuring unit 8 and corrects it by the temperature calculated by the temperature calculation unit 7. 10
Is a flow rate calculation and display section for calculating the flow rate by multiplying the flow velocity calculated by the correction calculation section 9 by the pipe cross-sectional area and displaying the flow rate.

In the above, when the upstream ultrasonic flowmeter sensor 1 generates ultrasonic waves, the ultrasonic beam 5 passes through the fluid and the surface wave 13 propagates through the pipe 3 as shown in FIG. The downstream ultrasonic flowmeter sensor 2 is reached. Similarly, when the downstream ultrasonic flow meter sensor 2 generates ultrasonic waves, the ultrasonic beam 4 and the surface wave 14 reach the upstream ultrasonic flow meter sensor 2 through the fluid and the pipe, respectively. .

The time points at which the ultrasonic beams 4 and 5 of the sensors 1 and 2 are transmitted and received are input to the propagation time difference measuring section 8 by the output signals of the sensors 1 and 2, and the measuring section 8 receives the ultrasonic beams 4 and 5. After calculating the propagation time, the difference in propagation time ΔT between the ultrasonic beams 4 and 5 is further output to the correction calculation unit 9, and the calculation unit 9 calculates the flow velocity of the fluid from the difference in propagation time ΔT. On the other hand, the surface waves 13, 1 of the sensors 1, 2
The output and reception times of 4 are input to the temperature calculation unit 7 by the output signals of the sensors 1 and 2.

FIG. 3 is a diagram showing the relationship between the level of ultrasonic echo and time, 21 is the echo of the ultrasonic transmission wave generated by the sensor 1, and 22 and 24 pass through the fluid. The ultrasonic wave echo received by the sensor 2 and the surface wave echo propagated through the surface of the pipe 3 and received by the sensor 2.

The ultrasonic wave propagating in the medium changes its propagation speed depending on the temperature, and the time it takes to reach the target changes.
FIG. 4 shows the propagation characteristics of this ultrasonic wave. When the ultrasonic wave propagation velocity is υ ₁ at a low temperature t ₁ , when the temperature rises to t ₂ , this velocity is greater than υ ₁ . It shows that it becomes late υ ₂ . In this case, since the surface echo 22 shown in FIG. 3 is delayed, it becomes a surface wave echo 23 shown by a dotted line.

As shown in FIG. 4, since there is a constant relationship between the ultrasonic wave propagation time and the temperature, the temperature calculation unit 7 calculates the surface wave 13 from the propagation time of the surface wave 13 between the sensors 1 and 2. 1
It is possible to determine the temperature of the fluid in the pipe 3 from the propagation velocity of the pipe 3 and the propagation velocity.

For this reason, the correction calculation unit 9 which receives the propagation time difference ΔT between the ultrasonic beams 4 and 5 from the propagation time difference measurement unit 8 to obtain the velocity of the fluid has the surface wave 1 calculated by the temperature calculation unit 7.
The current temperature calculated from the propagation velocities of 3 and 14 is input to correct the flow velocity of the fluid, and the ultrasonic beam
The flow velocity of the fluid is the error corrected by the change in the propagation velocity of No. 5.

The corrected flow velocity of the fluid is input to the flow rate calculation display unit 10, and the display unit 10 multiplies the flow velocity by the pipe cross-sectional area to obtain the flow rate, and then displays it.

As described above, since the temperature of the fluid flowing in the pipe is obtained from the surface wave propagating in the pipe, it is not necessary to dispose a temperature sensor in the pipe as in the conventional device, and the sensor mounting space of the pipe is not required. Can be made small, and the output processing circuit of the sensor can be simplified because it becomes a circuit that processes only ultrasonic waves.

[0024]

According to the ultrasonic flowmeter of the present invention, the time difference measuring means for transmitting the ultrasonic waves propagating in the fluid is inputted from the ultrasonic flowmeter sensor on the upstream side and the ultrasonic flowmeter sensor on the downstream side. Outputs the propagation time difference, and the pipe temperature calculation means that inputs the time of transmitting and receiving surface waves propagating in the pipe outputs the fluid temperature, and the flow velocity and flow rate calculation means that inputs the ultrasonic propagation time difference and the fluid temperature. After calculating the temperature-corrected flow velocity of the fluid, calculating the flow rate of the fluid eliminates the need for the temperature sensor used in conventional devices, and reduces the sensor mounting space for piping. The output processing device can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an ultrasonic flowmeter according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the action of ultrasonic waves according to the above-mentioned embodiment.

FIG. 3 is an explanatory diagram of echoes of ultrasonic waves according to the above embodiment.

FIG. 4 is a propagation velocity-temperature characteristic diagram of ultrasonic waves according to the embodiment.

FIG. 5 is an explanatory diagram of a conventional ultrasonic flow meter.

[Explanation of symbols]

 1 upstream ultrasonic flow meter sensor 2 downstream ultrasonic flow meter sensor 3 piping 4 ultrasonic beam from downstream 5 ultrasonic beam from upstream 6 ultrasonic flow meter processing circuit section 7 temperature calculation section 8 propagation time difference measurement Part 9 Correction calculation part 10 Flow rate calculation display part

Claims (1)

[Claims] 1. An ultrasonic flowmeter sensor, which is provided on a surface of a pipe through which a fluid flows, and is installed at intervals in a flow direction of the fluid, and an inside of the pipe of the two ultrasonic flowmeter sensors. The time when the ultrasonic wave emitted from the ultrasonic flow meter sensor located on the upstream side of the fluid propagates to the ultrasonic flow meter sensor located on the downstream side and from the ultrasonic flow meter sensor located on the downstream side to the inside of the piping Propagation time difference measuring means for measuring the difference between the time when the emitted ultrasonic wave propagates to the upstream ultrasonic flow meter sensor and the time when the ultrasonic wave propagates on the surface of the pipe between the two ultrasonic flow meter sensors. From the same, and means for calculating the flow velocity and flow rate of the fluid flowing in the pipe from the propagation time difference and the pipe temperature.