SU1765699A1 - Vibration-type mass flowmeter - Google Patents

Description

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(21) 4757683/10 (22) 09.11.89

(46) 09/30/92. Bul Mg 36 f (71) State Scientific Research - 5 Institute of Thermal Power Engineering

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(72) S.A. Zolotarevsky and A.A. Shkurin: (56) 1. European Patent No. 0212782, K7rGO FJ / 84, 1986.

f 2GShsg (eM1ot | opModelD.MassFlowmeter fnstruqtioiTManuai, 1985.

(54) MASS VIBRATION RACE HODOMER

(57) Usage: periodically zeroing the flow meter electronics. SUMMARY OF THE INVENTION: The device comprises a flow sensor 1, a vibration excitation node 2, a signal removal node 3,4, an electronic converter 5, inputs 6.7 of a converter, a measurement unit 8, a vibration stabilization and stabilization unit 9, a summing amplifier 10, an installation controller 11 zero, reference voltage source 12, normally closed 13 and normally open 14 and 15 contacts. 2 sludge.

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The invention relates to instrumentation, namely, devices for measuring the mass flow of the medium, and can be used to create mass vibratory flowmeters designed to measure the flow of various, including aggressive, polluted liquids and compressed gases in petroleum, chemical, metallurgical and other industry

A mass vibrating flow meter is known, consisting of a flow sensor comprising piping mounted on the housing with vibrations with an oscillation excitation unit and two signal pickup nodes, and an electronic converter with two inputs connected to the corresponding signal pickup nodes and two outputs, the first of which is connected to the oscillating node, and the second is the output of a summing amplifier with a measuring input, the second input of which is connected to the regulator The torus of installation zero 1.

The closest to this invention in its technical essence and the achieved result is a mass vibratory flow meter, which consists of a flow sensor that contains pipelines attached to the body with the possibility of oscillations with oscillations excitation unit and two signal pickup sites, and an electronic converter with two inputs connected to the corresponding pickup nodes and two outputs, the first of which is connected to the oscillation drive unit, and the second is the output input of its constituent summing amplifier with measurement input, a second input coupled to a regulator 2 zero setting.

Both described devices provide, in the absence of flow, compensation for both the systematically displaced zero flow sensor due to phase and, accordingly, time shift between signals from the first and second signal pickup nodes, and the unsystematic displacement of the electronic transducer caused by time and temperature drift characteristics of the elements included in it,

The disadvantage of both devices is the impossibility of compensating for the zero displacement of the electronic converter in the presence of flow through the device, which reduces the measurement accuracy by 1.5–2 times or more and makes it necessary to reduce the verification interval.

The purpose of the invention is to improve the accuracy of flow measurement and increase the verification interval.

The goal is achieved by the fact that in a mass vibration flow meter, consisting of a flow sensor, comprising an excitation unit and two signal pickup units, an electronic converter with two inputs,

connected to the corresponding nodes

signal pickup and output summing

amplifier whose measuring input

connected to the first output of the electronic

The converter, the second output of which is connected to the input of the excitation unit, and the second input to the output of the bias voltage regulator, is introduced a source of reference voltage, one normally closed and two

normally open synchronized contact, the second input of the electronic converter is connected to the second node of the signal pickup through a normally closed contact, and through the first normally open contact to the first pickup node, and the source of the reference voltage is connected to the third input of the output summing amplifier .

Figure 1 shows a block diagram of a mass vibratory flow meter; Fig. 2 shows an example of a circuit diagram of a summing amplifier with a zero setting controller connected to it, and

source of reference voltage.

Mass vibratory flow meter (figure 1) consists of a flow sensor 1, containing pipelines mounted on the housing with the possibility of oscillations (the housing and

The pipelines in the drawing are conventionally not shown) with an oscillation drive unit 2 and 3 and 4 signal pickups placed on them, an electronic converter 5 with inputs 6 and 7, which contains a block 8

measurement unit 9 of the excitation and stabilization of oscillations, summing amplifier

10 and the controller 11 of the installation zero. In addition, in the electronic Converter 5 additionally entered the source 12 of the reference

voltage, normally closed contact 13 and normally open contacts 14 and 15. Both in the known and in the proposed device, the measurement unit 8 is connected to the summing amplifier 10 and the block 9

excitation and stabilization of oscillations, which in turn is associated with the excitation unit of oscillations of the flow sensor 1, and the summing amplifier 10 is connected with the regulator

11 installations zero.

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 Figure 2 shows a schematic diagram of summing amplifier 10 with a zero setting controller 11 connected to it and a reference voltage source 12 and Scot & performed on a precision electronic June amps D1-D3 DKT40UD17), field-effect transistor VT1, - 4CyyOshum1stabilitron VD1 (D818E) and re "3 .. іл

Sistors R1-R9.

 I The device works as follows tj3bM sp-fli operating mode and in the mode of primary and periodic verification with the absence of the STED Ј- «« «. . -№vii consumption input 6 electronic

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Converter 5 is connected to node 3. Vb wtri & r "vlA - tel

signal ma, input 7 - with node 4 signal removal,

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and the source 12 of the reference voltage is switched off “r“ 5 ““: JK:, ..

from the summing amplifier 10. At

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Devices unit 8 measurements amplifies

Guided for move 6 signal from node 3 removal

JUUfr rt- & Ј &. # ElHpif &, lignal and feeds it to the input of block 9 is excited by a% of the oscillation stabilization, which, in turn, generates impulses eg. .

with a frequency equal to the frequency of the pipelines of the sensor 1

the flow rate that is fed to the oscillation drive unit 2.

Takigi manner, are provided on the pipelines own oscillation frequency stabilization those BTA koloNshTy said amplitude is performed by comparing ySh blrke E drive and stabilize the oscillation amplitude proportional Tklebany piping signal Zmr ony unit 8 and the reference signal and the corresponding voltage variations pulses supplied and oscillation excitation unit 2 At the same time, in block 8 of measurement, the signal from the input signal 6 of the signal pickup node 3 is compared with the signal similar to it, by „W - ,,

stepping on input 7 from node 4 of the signal pickup. At the output of measurement block 8, a voltage is generated and is proportional to the time shift between the specified signals that are fed to the first (measuring) input of the summing amplifier 10. The specified time shift is the algebraic sum of the initial time shift due to unequal the amplitude of oscillations of the sides of the pipelines and the possible difference in the shape of the signals from nodes 3 and 4 of the signal pickup and the time shift proportional to the mass flow rate measured from food. Compensation of the initial time shift and the corresponding part of the voltage 11 of is produced in the absence of flow through the device by changing the bias voltage supplied to the second input of the summing amplifier 10 from the zero setting regulator 11 until the output voltage reaches zero.

ivyh Thus, the voltage Kvyh will be directly proportional to the mass flow.

Operating experience of flowmeters of this type shows that the magnitude of the initial time shift between signals from the signal pickup units of this flow sensor remains almost unchanged throughout the entire operation of the device. At the same time, there is a change.

5 output voltage due to temporal and temperature drift of the elements of the electronic converter.

The adjustment mode is intended to compensate for this change.

0 after calibration of the flow meter in the absence of flow, open the normally closed contact 13 and close the normally open contacts 14 and 15. At the same time, the inputs 6 and 7 of the electronic converter 5

5, signals from one node 3 of the signal acquisition, i.e. the time shift between these signals is zero. By varying the value of the reference voltage Don, supplied from the source 12 of the reference voltage to the third input of summing amplifier 10, one obtains a zero value of the voltage 11V. The obtained value of the reference voltage is kept until the next calibration of the flow meter in the absence of

5 consumption.

The adjustment of the flow meter in the presence of flow is carried out by switching the device to the adjustment mode, followed by a change in the bias voltage

0 UCM supplied from the regulator 11 of setting zero to the input of summing amplifier 10 to obtaining the zero value of the output voltage Uv.

The output of the source 12 of the reference voltage5 is not advisable to bring to the socket of the control, and the value of the reference voltage U0n should be fixed in the device passport

The summing amplifier 10 with its zero setting regulator 11 and the reference voltage source 12 connected to it is made according to the scheme shown in Fig. 2

The reference element of the reference voltage source is the precision stat5 bilitron VD1. Transistor VT1 has a current source to stabilize the current through Zener diode VD1 at 10 mA. The voltage from the support element VD1 is supplied to the operational amplifier D1, which is designed according to the voltage follower, which allows increasing the load capacity of the Zener diode VD1.

The positive voltage from the output of the chip D1 is fed to the inverter D2 with a transfer coefficient equal to one. A stabilized voltage from the outputs of D1 and D2 microcircuits, equal in magnitude and opposite in sign (± 8 V), is supplied to resistor R4, which establishes the polarity and magnitude of the reference voltage in the event of flow meter calibration in the absence of consumption. When adjusting the flow meter, the reference voltage is fed through pin 15 to the third input of the summing amplifier, made on the D3 chip. The total gain of the summing amplifier is set by a resistor R7 to obtain the necessary gain of the measured voltage of the Weas. On the resistor R9 there is a zero setting regulator.

In the flow meter trimming mode, in the presence of flow, contact 15 is closed, the reference voltage equivalent to the imbalance of the flow sensor is fed to summing amplifier 10, and the output voltage Uvyh is set by resistor R9 to zero.

As follows from the above, the flow meter can be adjusted at any frequency, for example, with each change in ambient temperature, once a day, etc., when there is a flow. Due to this, the calibration interval of the flow meter can be increased, which in this case will be determined only by a change in the calibration characteristic

a flow sensor that changes extremely slowly. For example, the calibration interval of a flow meter can be increased from 1 year to 3-4 years.

Claims (1)

Thus, the stated technical solution provides an increase in the accuracy of flow measurement and an increase in the intertesting interval by providing the possibility of a regular adjustment of the flow meter without shutting off the flow. Claims of the Invention Mass Vibration Flowmeter, consisting of a flow sensor, comprising an excitation node and two signal pickup nodes, an electronic converter with two inputs connected to the corresponding signal pickup nodes, and an output summing amplifier, whose measuring input is connected to the first output of the electronic converter, the second the output of which is connected to the input of the excitation unit, and the second input - to the output of the bias voltage regulator, which, in order to increase the accuracy and increase verification interval, a voltage source is introduced into it, one normally closed and two normally open synchronized contacts, the second input of the electronic converter is connected to the second pickup node through a normally closed contact, and through the first normally open pin, the source of the reference voltage through the second normally open contact is connected to the third input of the output summing amplifier.