RU2619832C1 - Method for calibrating electromagnetic flowmeter without removal from pipeline - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: method for calibrating the electromagnetic flowmeters without removal from the pipeline relates to instrument engineering, namely to the methods for measuring the electroconductive liquid flow by the electromagnetic flowmeters and calibrating the electromagnetic flowmeters. Voltage supply is fed to the input of the measuring device formed by the resistor voltage divider connected to the excitation windings of the primary flow converter. The resistor voltage divider, permanently connected to the excitation windings of the primary converter, generates the signals from the feeding current, simulating a fluid flow, which is received in the processor by a certain algorithm through the measuring analog-to-digital converter and a switch in the form of a digital code. The processor compares the current signal values, generated from the feeding current by the resistor voltage divider, in the digital form with the reference values preset in the processor memory during manufacture.

EFFECT: optimizing the verification process and the flowmeter diagnostics.

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Description

The invention relates to the field of instrumentation, and in particular to methods for measuring the flow rate of electrically conductive liquids using electromagnetic flowmeters and calibration of electromagnetic flowmeters.

A known method of calibration and calibration of electromagnetic flowmeters (RU, patent No. 2330246, G01F 25/00, 2006), which consists in placing in a magnetic field a primary flow transducer of an induction coil, integrating the electrical voltage at the output terminals of the coil induced by the magnetic field of the primary transducer, and supplying voltage to the input of the measuring device of the electromagnetic flow meter.

The disadvantage of this method is the inability to verify the flow meter, which is in operation, without dismantling it from the pipeline.

A known method of checking electromagnetic flow meters without removal from the pipeline (RU, patent No. 2432551, GO1F 25/00, 2010). A method for checking electromagnetic flowmeters involves converting the magnetic field of the primary transducer into electrical voltage using an induction coil located in the magnetic field of the flowmeter, integrating the electrical voltage obtained at the output terminals of the induction coil, and determining the experimental conversion coefficient of the flow meter K _P. Before the start of operation, the conversion coefficient is determined using two induction coils, respectively, one of which is in the channel and the other is located outside the channel of the flowmeter, and the ratio of conversion coefficients of the electromagnetic flowmeter K = K _P / K _P2 , where K _P is the conversion coefficient determined using an induction coil located in the channel of the flow meter, and K _P2 is the conversion coefficient determined using an induction coil located outside the channel of the flow meter, at the volume during calibration of the flow meter without removal from the pipeline determine the conversion coefficient K _P2 by integrating the voltage at the output terminals of the induction coil located outside the channel, calculate the conversion coefficient K _P2 and based on it calculate the calculated value of the conversion coefficient K _P according to the formula K _P = K ⋅K _P2 .

The disadvantage of this method is the presence of an additional induction coil, which increases the cost of the flow meter, the complexity of calculating the coefficients, and the calibration does not take into account the state of the electrodes and the electrical conductivity of the measured liquid.

In the known method for checking electromagnetic flowmeters (RU, patent No. 2270420, GO1F 25/00, 2004), which consists in placing the primary transducer of the electromagnetic flowmeter of the induction coil in the magnetic field, integrating the electrical signal, and also supplying the voltage released to the resistance included sequentially in the power supply circuit of the excitation windings of the primary Converter, to the input of the measuring device through a symmetrical resistor voltage divider and measuring the received signal, produce statement with passport data upon release from production.

The disadvantage of this method is the impossibility of calibrating a flow meter in operation without dismantling it from the pipeline, and the calibration does not take into account the electrical conductivity of the measured liquid and the electrochemical processes on the electrodes of the primary transducer.

Closest to the proposed method is a method for calibrating electromagnetic flowmeters (RU, patent No. 2494354, GO1F 25/00, 2012), which consists in applying to the input of the measuring device included in the flowmeter a voltage generated by a symmetrical resistor voltage divider connected to excitation windings and electrodes of the primary flow transducer in contact with the liquid are energized from the flowmeter measuring device, reference signals are formed from the energization current by the resistor voltage divider through the electrodes in contact with the measured liquid, it is fed to the input of the measuring device, amplified, converted to digital form and displayed on the measuring device, the value of the control volume of liquid for a certain time is read from the indicator and the data obtained is compared with the value of the passport data of the control volume during initial verification at release from production, and in case of inconsistency, the trimming resistor is adjusted.

The disadvantage of this method is the need to connect, when checking in operation, a resistor voltage divider to the primary flow transducer, the verification results are processed manually, during the verification interval, the flowmeter is not being diagnosed.

The task of the invention is to optimize the verification process and diagnosis of the flow meter.

This technical result is achieved by a method for verification of electromagnetic flowmeters resistor voltage divider R _1, R _2, R _3, R _4, permanently connected to the windings of the excitation OB primary converter forms of current powering the I _zap signals simulating fluid flow, which through measuring the analog-digital converter 5 and the switch 6 in the form of digital code received by a certain algorithm in a processor 3. The processor compares the current values of signals generated from the powering current I p _zap zistornym voltage divider in digital form in a processor memory preloaded during manufacture reference values.

If the current code values deviate from the threshold values of the reference code, the processor 3 issues a command to the program-controlled current source 4 to correct the supply current I _{zap of the} field windings.

From the processor in verification mode, information is displayed on the indicator on the compliance or non-compliance of the flowmeter with metrological requirements.

The invention is illustrated by the drawing of FIG. 1, where:

1 - pipeline primary flow sensor;

2 - measuring ADC;

3 - processor;

4 - software-controlled current source;

5 - ADC;

6 - switch.

The primary flow transducer consists of pipeline 1, electrically isolated from the pipeline electrodes E1, E2 and two field windings OB1, OB2.

The excitation windings are powered from a program-controlled current source 4. The resistor voltage divider consists of four precision resistors R ₁ , R ₂ , R ₃ , R ₄ connected accordingly and connected in accordance with the drawing of FIG. one.

The method is as follows.

The supply current I _zap , passing through the field windings OB1, OB2 and the resistor voltage divider R ₁ , R ₂ , R ₃ , R ₄ , generates signals simulating fluid flow. These signals are converted into a digital code in the ADC 5 and, according to a certain algorithm, are supplied to the processor 3 by means of the switch 6. In the processor 3, the current values of the digital code are compared with the reference values preset in the processor memory upon discontinuation. If the measured values of the codes of the threshold values of the reference value are exceeded, the processor 3 issues a command to the program-controlled source 4 to correct the supply current I _app .

The technical result consists in bringing the current measured values of the digital code into conformity with the reference values.

The verification method provides for verification in the verification mode, output from the processor 3 to a digital indicator of information on the conformity or non-compliance of the metrological characteristics of the flowmeter with the reference.

Claims (1)

A method for calibrating electromagnetic flowmeters without removing from the pipeline, comprising applying to the input of the measuring device a voltage generated by a resistor voltage divider connected to the excitation windings of the primary flow transducer, characterized in that the resistor voltage divider permanently connected to the excitation windings of the primary transducer is powered by software controlled source, generates signals simulating the flow in the measuring analog-to-digital converter is entered into a digital code, by means of a switch according to a certain algorithm the digital code is supplied to the processor, a comparison is made with the reference value of the digital code preset in the processor memory when discontinued, when the current values of the digital code deviate from the threshold values of the reference, a command is issued to correct the winding current excitation program-controlled current source, the processor in verification mode provides digital information to the indicator of compliance or non-compliance with the flow Era metrological characteristics.

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