SU972223A1 - Pulse single-channel ultrasonic flowmeter - Google Patents

Description

(54) PULSE SINGLE-CHANNEL ULTRASONIC

FLOW METER

one

The invention relates to a measuring technique and can be used to measure the flow of liquid and gaseous media in the oil and gas, chemical, food, hydrometallurgical and other sectors of the industry.

Known pulsed single-channel ultrasonic flow meter, based on the measurement of the difference in time intervals during the propagation of ultrasound along the stream and against it. The measurement is carried out with the help of a highly stable generator whose discrete pulses fill the measured time intervals. The counter-counted pulse difference is a measure of flow 1.

The disadvantage of this flow meter is the low measurement accuracy, which is limited both by the magnitude of the discrete counting unit, i.e. the oscillation period of the highly stable generator, and the absence of corrections for speed changes

the spread of ultrasound due to the inadequacy of physicochemical environmental parameters.

Closest to the proposed is a single-channel ultrasound

a flow meter containing two acoustic transducers located on opposite walls of the pipeline at an angle to its axis and connected via a switch with a probe pulse generator

5 and with series-connected amplifier, selector, pulse counter, memory register, return difference calculation unit, and recorder 2.

Q However, the known device has insufficient measurement accuracy.

The purpose of the invention is to improve the measurement accuracy.

The goal is achieved by introducing a state decoder, a frequency divider, a series-connected reference oscillator, a driver, a time-amplitude converter, an analog-to-digital converter, and a code converter in a single-channel pulse ultrasonic flow meter, and the state decoder is connected to the output of a frequency divider. its output is connected to the inputs of a switch, a memory register, a time-amplitude converter, a pulse counter, a probe pulse generator The output of which is connected to the selector and to the registering device, the outputs of the reference generator are connected to the inputs of the frequency divider and the selector, the inputs of the pulse counter are connected to the high bits of the memory register, and its lower bit is connected to the output of the code converter, while the output of the amplifier connected to the input of the imager. FIG. I presents the block diagram of the proposed device; in fig. 2 - time diagrams. The flow meter contains a series-connected reference generator 1, a frequency divider 2, a decoder of 3 states, a generator of 4 probe pulses, a switch 5 that communicates with a decoder of 3 states, converters 6 and 7, and an amplifier 8, to the output of which a selector is connected in series. 9, a pulse counter 10, a memory register 11, a unit for calculating the difference of reciprocal values, a recording device 13. The flow meter also contains series-connected interval driver pulses 14, a time converter 15 oh interval-amplitude, analog-to-digital converter 16 and code converter 17. The flow meter works as follows. The reference generator 1 generates highly stable pulses of frequency f (Fig. 2a), which are divided up to the frequency of clock pulses in frequency divider 2 and fed to a decoder of 3 states, which is used to synchronize the operation of the flow meter as a whole. According to the first clock pulse received at the input of the generator 4 of the probe pulses, an excitation pulse is generated, which through the switch 5 is fed, for example, to the radiating converter b (Fig. 26). At the same time, a start pulse is applied to the selector 9 from the generator 4 of probe pulses, through which the selector 9 starts to pass the pulses of the reference generator 1 to the input of the counter 10 pulses. The acoustic signal emitted by the transducer 6 passes through the current controlled medium during Tp at an angle ot to the pipeline axis, is converted in the receiving transducer 7 into an electrical signal (Fig. 2c) and through the switch 5, the amplifier 8 is fed to the selector 9, which operates and interrupts the flow of pulses of the reference generator I to the counter 10 pulses (Fig. 2d). Simultaneously with the closing of the selector 9, the shaper 14 of the interval pulses is started, forming an additional time interval (Fig. 2e) from the time of arrival of the information pulse corresponding to the received ultrasonic signal until the next pulse is received from the continuous sequence generated by the reference generator 1, m. e. within tg - additional time interval; - frequency reference oscillator. The generated time interval t is converted in the converter 15 time interval-amplitude to voltage, the level of which is stored on the storage capacitor of the time-amplitude-converter (Fig. 2e). In order to reduce the requirements for the analog-to-digital converter 16 in terms of conversion speed, the storage time of the storage capacitor 15 of the converter 15 is sufficiently large (Fig. 2e). For this, the connection of the storage capacitance with the analog-to-digital converter 16 is carried out using a source follower having a large input resistance and also included in the time interval-amplitude component of the converter 15. At the end of each measurement cycle, a forced discharge of the storage capacitance is provided, which is achieved by applying a short-duration discharge pulse (Fig. 2 g) from the 3-state resolver to the time-amplitude-amplitude discharge circuit of the converter 15. The analog-to-digital converter generates a code proportional to the transformed time interval, however, the transformed time interval is not the desired one, but complements the desired one up to the time interval of a single value of the discrete count, i.e., to the value t + tg; ; where t is the desired time interval. Since the period of discrete counting pulses is strictly constant and equal to the conversion range of analog-to-digital converter 16, the desired code value of the time interval is m k - n, where rn is the code value of the desired time interval; k - max transform range code value; n - the current code value of the analog-to-digital converter. This conversion is carried out in a code converter 17, which converts the n values of K of the bit code into m auxiliary values of K of the bit code. The code value of the time interval from the converter 17 of the code is fed to the inputs of the lower bits of the memory register 11 simultaneously with the code values of the counter 10, the inputs of which are connected to the high bits of the memory register 11. After the end of the recording, the counter 10 is reset to zero by the clock pulse coming from the decryptor 3 states, which is necessary to ensure readiness for the next measurement cycle, in which the excitation pulse of the generator 4 of the probe pulses through the switch 5 is fed to the converter 7.

In this case, the acoustic signal propagates against the flow at an angle to the axis of the pipeline. The acoustic signal passed through the controlled medium is converted in the converter b into an electrical signal, then through the switch 5 and the amplifier 8 is fed to the selector 9. The time of ultrasound propagation is measured at a discrete interval of 4 and the additional time interval is converted in the sequence described above. . In this case, the memory register 11 is filled with information about the propagation time and ultrasound against the flow of the medium. After the information is stored in the memory register 11 by means of the 3 state decoder, the measurement cycle is repeated.

The values of the measured time interval recorded in the memory register 11 are processed in the unit 12 for calculating the difference about (5 times the values realizing

function Y) Гп-г п - ™ is the number of memory register values corresponding to the time of ultrasound propagation along the medium flow or against it.

Taking inverse values from measured time intervals during ultrasound propagation in the flow and against it eliminates the need to introduce a hard-to-find correction for the square of the ultrasound propagation speed in a controlled environment, and the adopted algorithm of operation of the inverse difference difference calculator 12 allows you to record the flow rate for each the value of the time interval received in memory register 11.

The recording device 13 averages the measurement results and outputs at its output information in the corresponding units of the flow velocity or flow rate of the medium. Consideration of the direction of the flow velocity is achieved with the help of signals coming from a 3 state decoder.

The proposed device allows improving the measurement accuracy as well as expanding the field of application of ultrasonic flow meters.

Claims (2)

Invention Formula A pulsed single-channel ultrasonic flow meter containing two acoustic transducers located on opposite pipe walls at an angle to its axis and connected through a switch with a probe pulse generator and with series-connected amplifier, selector, pulse counter, 5 by a memory register, a unit for calculating the difference in inverse values and a registering device characterized by the 7th, that, in order to improve the measurement accuracy, a state decoder, a frequency divider, and also serially connected  reference oscillator, driver, time-amplitude-converter, analog-to-digital converter and code converter, with the state decoder input connected to the output of the divider J frequency, its output is connected to the inputs of the switch, memory register, time-amplitude-frequency conversion, pulse counter, probe pulse generator, the output of which is connected to the selector, and to the recording device, outputs 0 of the reference oscillator is connected to the inputs of the frequency divider and selector, the outputs of the pulse counter are connected to the senior bits of the memory register, and its low-order bit is connected to the output of the converter, the code, and the output of the amplifier is connected to the driver input. Sources of information taken into account in the examination 1. Japanese patent number 52-45511, cl. 111 A 132, 1977. 2. For the application of the Federal Republic of Germany No. 2547892, cl. G 01 F 1/66 1979. FIG. one