RU2645834C1 - Method and device for determining consumption in large diameter pipelines - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention relates to the field of measurement equipment and can be used to determine the flow of electrically conductive liquid media by means of an electromagnetic flowmeter with dip sensors of local velocity. Device includes current driver, current sensor based on mounting precision resistor and passive filter on chip resistors, four-key button keyboard. Method for determination of flow in large diameter pipelines ≥ 300 mm consists of measuring the local flow rate of controlled liquid at three points, which are located at fixed depth of immersion, by exciting alternating sign geomagnetic field, generating an information signal from the measured EMF value, determining the value of local and average velocity, and volume flow rate. Proposed device and method allows to increase the accuracy, stability, as well as to expand the dynamic range of measuring the flow rate of liquid in large diameter pipelines due to the method of processing information signals using the method of forming informative difference signal. To protect the device from external electromagnetic interference, internal common mode and ground currents, the common power lead of the device is isolated from local protective earth. To increase the accuracy of measurements of local velocity of controlled flow of liquid and to reduce the cost, simple method of statistical processing is used, which can be implemented in inexpensive microprocessor used in the claimed device. For example, the method of averaging out except emissions, by which the maximum and minimum values of digitized information signal are discarded, remaining n-2 values of this signal are averaged, and the value of digitized information signal obtained after averaging out is stored in operating storage of the device and used in further calculations.

EFFECT: increase the accuracy of measuring the flow of electroconductive liquid, save energy and expand the field of application.

2 cl, 5 dwg

Description

The invention relates to the field of measuring equipment and can be used to determine the flow rate of electrically conductive liquid media.

A known design of an electromagnetic flow meter. An electromagnetic flowmeter is based on measuring the difference in electrical potentials generated on electrodes in contact with a moving fluid flow, located perpendicular to both the magnetic field lines and the direction of fluid flow. An electromagnetic flowmeter contains a primary transducer (sensor), a liquid flow rate, a magnetic system with coils, in the gap of which a pipeline with electrodes is installed, a preamplifier, a current driver, an analog-to-digital converter (ADC), a microcontroller, a liquid crystal indicator, and a voltage reference source. The outputs of the current driver are connected to the input of the primary flow transducer, that is, the coils of the magnetic system. The outputs of the primary flow transducer, that is, the electrodes are connected to the input of the pre-amplifier, the output of which is connected to the first input of the ADC. The ADC output is connected to the input of the microcontroller, the first output of which is connected to the indicator input. An electromagnetic flow meter (EMR) includes a modulating signal driver and a voltage modulator. The output of the reference voltage source is connected to the first input of the reference voltage modulator, the second input of which is connected to the output of the modulator signal former, the input of which is connected to the second output of the microcontroller. The output of the reference voltage modulator is connected to the input of the current driver and to the second input of the ADC.

Such a technical solution allows for measuring the flow rate using an EMR and can be used in meters with pipelines with a diameter much larger than 300 mm of water, acids, alkalis, milk, beer (RF patent No. 2489684, G01F / 58 Electromagnetic flowmeter 2013, authors: .K. Nedzvetsky, V.B. Rogozin).

The disadvantages of this device are that the design of such EMF is rather cumbersome and complicated, since it requires the immersion of the sensitive elements of the submersible sensors of local speed at different depths, depending on the diameter of the pipeline. In addition, the rods on which the sensing elements (CE) of the submersible sensors of the local speed of electromagnetic flowmeters are mounted can have a considerable length and a sufficiently large transverse dimension to maintain strength and prevent vibration. Therefore, the use of such a sensor in the coolant flow will introduce distortions in the velocity profile and additional hydraulic resistance.

A known method of measuring fluid flow on a test flow meter device (IRA). Primary converters (sensors) of the tested flow meters are mounted on the test section of the pipeline and provide a “normal” kinematic structure of the flow from the outlet. Tests on flowmeters with different nominal diameters Du are provided by a set of interchangeable test pipelines or by a collector device for parallel stationary pipelines having autonomous locking elements at the inlet and outlet. “Normal”, that is, corresponding to a developed turbulent flow, a symmetric flow structure with a strictly limited radial velocity component (with limited flow swirl). Passive and active methods are used to indicate the boundaries of the flow averaging interval. The active method consists in forcibly changing the direction of flow at the exit from the highway. With the passive method, there is no effect on the flow. To measure the duration of the interval, time integrators with a fixed beginning and end of a time reference are usually used. The commonality of the process of creating and measuring the flow rate and the resulting commonality of the structure and the IRA allow us to describe this process with three basic equations

- equation of approximation

where Q _y - flow rate model; Q _y (t) is the flow rate of the fluid through the test flowmeter as a function of time t, the index y is the equivalent of the mass M of the fluid when the mass flow rate Q _M or volume V changes when the volumetric flow rate Q _V changes;

- measurement equation

where Q _yu is the measured flow rate; Y (t) is the amount of fluid entering the measuring tank; Y _∑ - the amount of fluid entering the measuring tank;

- the equation of the balance of costs or losses in the section "test flowmeter - measuring tank"

where Y _nomi - fluid loss; i - loss source number = 1, 2, 3, n.

This solution allows you to measure the flow of coolant or flowing fluid in static and dynamic loading. In the proposed classification (dynamic and static load), the main classification features are the method of obtaining information about the measurement results and the method of measuring the amount of flowing fluid. According to the first criterion, IRAs are divided into static and dynamic, according to the second, into volumetric and weighted ones (B. V. Biryukov, M. A. Danilov, S. S. Kivilis. “Test flowmeter installations.” Energy, Moscow, 1976, 144 pp. .; p. 5-11. 1. Structure and basic equations of the IRA ").

The disadvantage of the method of measuring the flowing fluid coincides with the disadvantages of the device of the selected analogue. In addition to these disadvantages, the method does not allow to measure the flow rate of liquids in pipelines of large diameters from 300 mm or more.

The closest technical solution to the proposed invention is a device containing three blocks of a speed meter (IS-1, 2, 3); each block of a measuring system includes: one primary EMR speed converter, a measuring block, that is, a block matching the outputs of the EMR with an external the circuit (which is not disclosed) contains a preamplifier, switch, ADC, microcontroller, multi-channel and autonomous DC power supplies, one computing unit for three speed meters (also not open um), comprising: a microprocessor, a memory unit, an indicator, chetyrehklavishnuyu Numeric keypad autonomous DC power supply, a measuring line with a nominal diameter DN 200 mm and more. All three speed converters are symmetrically mounted (fixed) on the measuring pipeline, the output of the speed converter is connected to the input of the measuring units, the output of the last blocks is connected to a computing unit of type IVB-1P. The second outputs of the measuring unit are connected to other speed converters. The composition of the flow meter includes: a sensitive element with two electrodes, a holder, a connector, and this combination is called a "speed converter". The measuring unit includes a rack, a speed converter, a lock chamber ШК-1 with a ball valve. Their combination is called the "module of the primary converter of local speed."

Such a device allows you to measure the speed and flow rate of the coolant in large pipelines based on the area-speed flow measurement method.

The main disadvantage of the known device for measuring the flow of coolant in large pipelines are: does not take into account the distortion of the initial velocity profile by the structural elements of submersible sensors of local speed immersed in the flow of a controlled fluid (Materials of the 16th International Scientific and Practical Conference "Commercial metering of energy carriers", comp. V. I. Lachkov, St. Petersburg, Polytechnic, 2002, pp. 397-400, Authors: Shinelev A.A., Burdunin M.N., Welt I.D.).

где N - число измерителей локальной скорости; α_i - нормированные коэффициенты скорости, v_i - значения локальной скорости в измерительных точках. Предлагают простой алгоритм вычисления, когда α_i равной между собой. При этом выходная величина расхода пропорциональна среднему значению показаний каждого измерителя скорости. Представляют профиль скорости в трубопроводе с круглым сечением в виде разложения по гармоникам Фурье по углу поворота θ, вокруг оси трубопровода. Используют тот факт, что при усреднении локальных скоростей, измеренных в любых трех точках, расположенных в поперечном сечении равномерно по окружности с центром, совпадающим с осью трубы, остаются только гармоники, кратные 6. Предлагают для уменьшения погрешности, обусловленной асимметрией профиля скорости потока число измерителей локальной скорости N выбирают кратной 3, а электромагнитные преобразователи скорости устанавливают равномерно по окружности, опоясывающей измерительное сечение. Калибровку и поверку теплосчетчиков и расходомеров осуществляют проливным или имитационным способами. При проливном способе калибровки и поверки на проливной установке УРОКС-400 мерный участок состоит из трех отрезков трубопроводов Ду 204 мм с присоединительными фланцами. Для имитационной поверки предлагают новый метод, основанный на определении комплексного коэффициента преобразования измерителя скорости. Показывают, что коэффициент преобразования характеризует отношение сигнала на электродах первичного преобразователя (датчика) при скорости 1 м/с к току или напряжению питания индуктора. Метод реализован в установке Поток-Т.Closest to the proposed invention, the technical solution is a method based on the use of submersible electromagnetic transducers of local speed, according to which the flow rate is calculated by the "area-speed" method. The measurement method "area-speed" is based on the measurement of local (local) speed. Using this method, the local velocity v is measured at one or several points of the cross-section of the pipeline, the cross-sectional area S is measured in the measured section of the pipeline, the average cross-sectional velocity of the controlled electrically conductive liquid (coolant) u is calculated, and the volumetric flow G is determined according to the expression:

where N is the number of meters local speed; α _i - normalized velocity coefficients, v _i - local speed values at the measuring points. They offer a simple calculation algorithm when α _{i is} equal to each other. In this case, the output flow rate is proportional to the average value of the readings of each speed meter. Represent the velocity profile in a pipeline with a circular cross section in the form of expansion in Fourier harmonics in the angle of rotation θ, around the axis of the pipeline. Use the fact that when averaging local velocities measured at any three points located in a cross section evenly around a circle with a center coinciding with the axis of the pipe, only harmonics that are multiple of 6 are proposed. To reduce the error due to the asymmetry of the flow velocity profile, the number of meters local speed N is chosen a multiple of 3, and electromagnetic speed transducers are installed uniformly around a circumference surrounding the measuring section. Calibration and calibration of heat meters and flow meters is carried out by pouring or simulation methods. With the pouring method of calibration and verification at the pouring installation UROKS-400, the measuring section consists of three sections of pipelines DN 204 mm with connecting flanges. For simulation verification, a new method is proposed based on the determination of the complex conversion coefficient of a speed meter. It is shown that the conversion coefficient characterizes the ratio of the signal on the electrodes of the primary transducer (sensor) at a speed of 1 m / s to the current or voltage of the inductor. The method is implemented in the Potok-T installation.

This solution provides measurements of the average velocity and flow rate of the coolant in large-diameter pipelines based on the area-speed flow measurement method (KM-5-B3 electromagnetic heat meters and KM-5-B3 counter-flow meters of submersible type for commercial metering of heat and coolant in pipelines large diameters ”(Materials of the 16th International Scientific and Practical Conference“ Commercial metering of energy carriers ”, compiled by VI Lachkov, St. Petersburg, Polytechnic, 2002, pp. 397-400, Authors: Shinelev AA, Burdunin M. N., Welt I.D.).

The main disadvantage of the known method for measuring the flow rate of coolant in large-diameter pipelines is that when measuring the local velocity at points 0.242R (where R is the internal radius of the pipeline), replacing the velocity coefficient α of the undisturbed flow of the coolant with the tabular constant α _tab will increase the measurement error average speed and flow rate of controlled fluid. In addition, the disadvantage is the lack of protection in the device from the influence of external electromagnetic and common-mode interference through power supplies.

The objective of the present invention is to improve the accuracy of measurements of the flow rate of conductive fluid in pipelines of large diameters, save energy consumed by the device, improve noise immunity. Thanks to these properties, the scope of application is expanding. The goals are achieved by compiling the optimal algorithm and program for calculating the flow of coolant.

1. The technical result is achieved by the fact that in the device for determining the flow rate in pipelines of large diameters, which contains a measuring pipeline, including three local speed meters, each of which consists of a primary signal converter and a local speed immersion sensor connected to it, including a magnetic system with coils , the submersible part of which contains a sensing element with electrodes, and immersed in a pipeline completely filled with an electrically conductive liquid, a multichannel unit to DC power, an autonomous DC power supply, three primary signal converters based on electromagnetic flowmeters, which contain a pre-amplifier, a switch, an analog-to-digital converter, a microcontroller, a computing unit that contains a microprocessor, a memory unit and an indicator, while the electrodes output through a pre-amplifier, a switch, an analog-to-digital converter is connected to the input of the microcontroller, and the outputs of the microcontrollers are connected to the input of the micro the processor of the computing unit, the microprocessor output is connected to the memory unit and the indicator, the output, that is, the positive pole of the autonomous DC power supply unit is connected to the power circuits of the microprocessor, memory unit, indicator at points e, f, f, h, one of the outputs, i.e. the positive pole of the multi-channel power supply is connected to the power circuits of the pre-amplifier, switch, analog-to-digital converter, microcontroller at points a, b, c, d, the control output f of the microcontroller is connected to the switch for the purpose of issuing control commands f1, f2 to it, the control output e of the microcontroller is connected to an analog-to-digital converter, the control output p of the microprocessor is connected to the corresponding control inputs p of the microprocessors of the primary signal converters;

it additionally introduces a current driver, including keys K1, K2 with a switch; a current sensor based on a reference precision resistor and a passive filter on chip resistors, which is part of the primary signal converters and includes a reference resistor Rop; four-button push-button keyboard; moreover, in the compiled program, the values of the information difference signal Ci and the reference local velocity vе were used for piecewise linear approximation of the nominal static characteristic of the local speed meter, the number of segments of the approximation of the nominal static characteristic was set to at least three, the sensitive elements of the local speed immersion sensors are immersed inside the pipeline completely filled with liquid on the electroconductive h _1,2,3 depth, measured inner diameter ruboprovoda D, the diameters d submersible sensors local speed sensors, distance from the inner wall of the pipeline to measuring points Y _1-3, its value is the sum of _{Y 1-3 = h 1-3 + X eff} , where X _eff - distance from end submersible sensors of local speed to the measuring point, for submersible sensors of local speed, X _eff = 2 mm, these geometric parameters are stored in the memory of the computing unit;

moreover, the outputs of the coils of submersible sensors of local speed are connected through current drivers, current sensors to the outputs, that is, the positive poles of the multi-channel power supply unit of the coils, powered from an industrial AC voltage network; the output, that is, the negative pole of the multi-channel power supply unit of the coils is connected to the negative pole of the device at point B, the other output of the multi-channel power supply unit through a current sensor based on a reference precision resistor and a passive filter on chip resistors, a current driver is connected to the input of the coil, control outputs the microcontroller g1 and g2 are connected to the keys K1 and K2 of the current driver, and the output of the current sensor is connected to the input of the switch; moreover, they protect the electrode circuit and the input circuit of the preamplifier from the penetration of external electromagnetic interference, from common-mode interference and earth currents of the device, for this the common bus of the device at point B is electrically isolated from the local protective ground at point B, while the protective casings of the primary signal converters at B are connected to the local protective earth at point h;

moreover, the negative poles of the separate multichannel and autonomous DC power supplies are connected to the negative pole of the device’s common power bus at point B, the negative pole of the device’s common power bus at point B is electrically isolated from the local protective earth at point B, the protective casings of the primary signal converters at B are connected to the local protective earth at point h; moreover, the microprocessor interacts with the microcontrollers of the three primary signal converters by polling them and issuing control commands, and the operator sends commands to the microprocessor through the four-button keyboard, reads the information from the indicator and stores it in the memory unit of the computing unit

где N - число измерителей локальной скорости; α_i - нормированные коэффициенты скорости, v_i - значения локальной скорости в измерительных точках; величину расхода контролируемой жидкости вычисляют как произведение средней скорости на площадь измерительного сечения: G_v=u⋅S, площадь измерительного сечения рассчитывают по формуле: S=πD²/4-S_M; где S_м - суммарная площадь миделей датчиков локальной скорости:

где d - диаметр датчика скорости; h_i - глубина погружения i-го датчика локальной скорости, i=1, 2, 3;2. The technical result is also achieved by the fact that in the method for determining the flow rate in pipelines of large diameters, in which the local speed meters of the device are calibrated by the pouring method with a completely measured portion of the pouring stand, the average velocity u of the controlled fluid in the measured portion of the pipeline is calculated according to the expression :

where N is the number of meters local speed; α _i - normalized velocity coefficients, v _i - local speed values at the measuring points; the flow rate of the controlled fluid is calculated as the product of the average velocity by the measuring cross-sectional area: G _v = u⋅S, the measuring cross-sectional area is calculated by the formula: S = πD ² /4-S _M ; where S _m - the total area of the midsection of the local speed sensors:

where d is the diameter of the speed sensor; h _i - immersion depth of the i-th local speed sensor, i = 1, 2, 3;

in it, additionally, in the calibration mode of the local speed meters, the nominal static characteristic is determined, a series of values of the reference local velocities ve are set on the pouring bench in the measuring section at the measuring point of the submersible local speed sensor; for each value of the local velocity ve they measure the value of the information difference signal Ci of the local speed meter, and the values of the reference local velocity ve vary in the range (0.2, ..., 5) m / s, in addition, the value of the information difference signal Ci is measured at zero speed of the controlled electrically conductive liquid in the pipeline, the obtained values of the difference signal Ci and the reference velocity ve are stored and stored in the memory of the microcontroller of the primary signal converter in automatic mode asno composed of algorithms and programs;

during the measuring cycle T during the time intervals t1, t2, t3, t4 in the microcontroller set the levels of logical control signals: in the time interval t1 - logical control signals g1 = 1, g2 = 0; in the time interval t2 - logical control signals g1 = 0, g2 = 0; in the time interval t3 - logical control signals g1 = 0, g2 = 1; in the time interval t4 - logical control signals g1 = 0, g2 = 0; under these conditions, respectively, the microcontroller generates logical control signals g1, g2, a positive half-period of the coil current waveform I ₊ is generated in the current driver in the time interval of the logical control signal g1 of duration T _g1 , the information signal U _{± v} proportional to the local velocity of the controlled fluid v is removed from the electrodes , it is fed to the preamplifier input and output are coordinated and amplified information signal kU _{± v,} then digitize the signal to obtain at the outlet analogous ovo-digital converter the digitized information signal kU _{'± v,} proportional to the local velocity v, after the pause time T ₀ = t2 form a negative half-cycle square wave current coil I _- in the time interval of the logical control signal g2 duration T _g2, wherein the trailing edges of the control logic signal, g2, the negative half-period of the meander of the coil current I _- and the information signal Uv are shifted relative to the leading edges of the control logic signal g1, the positive half-period of the meander of the coil current I ₊ and an information signal U _{+ v} for a pause time T ₀ = t4 = t2, while in the time intervals t1 and t3 positive and negative half-periods of the current meander through the coil are generated and the amplified and consistent information signal kU _{± v} and the current signal through the coil U _{I are} digitized proportional to the current in this circuit, taken from the reference resistor Rop of the current sensor, and the information signal kU _{± v is} digitized in the time interval T ₁ after the transition time interval Tc is completed, then the signal proportional to the current through the coil U _{I is} digitized in the time interval T ₂ reserved by the microcontroller for measuring the current through the coil, in the time intervals of the formation of the positive and negative half-periods of the current meander through the coil t1 and t3, the microcontroller accordingly sends a control command f ₂ to the switch, while from the output of the pre-amplifier to the analog-digital input the converter supplies an information signal kU _{± v} , then the microcontroller sends a control command e to be digitized repeatedly n times, with a uniform or uneven step, to an analog ovo-digital converter, n values of the digitized signal kU ' _{± v are} stored in the RAM of the microcontroller for further processing, then the microcontroller sends the control command f ₁ to the switch, while the current sensor U _{I is} fed to the ADC input from the current sensor and to its the output has a digitized signal of the current sensor through the coil U ' _I , then the microcontroller sends a control signal - the command is to digitize to the ADC, the digitized signal of the current sensor through the coil U' _{I is} fed to the input of the microcontroller and stored in its opera memory for further processing,

they also reduce the random component of the relative error of measuring the local speed: n values of the digitized information signal kU ' _{± v, j} , where j = 1, 2 ... n, are received at current time intervals through a coil of positive polarity t1 and negative polarity t3 and store them in the operational the memory of the microcontroller is processed according to a pre-compiled methodology implemented in the program for the microcontroller using the averaging method with the exception of emissions, by which the maximum and minimum Achen kU digitized information signal _{'± v, j,} the remaining n-2 values that averaged signal is stored in the RAM of the microcontroller and are used in subsequent calculations,

they also eliminate the influence of the instability of the information signal U _{± v} associated with the instability of the supply current of the coils and at the same time eliminate the bias signal U ₀ due to the occurrence of secondary electrochemical processes on the electrodes, in automatic mode, according to the compiled algorithm and the program for the microcontroller, determine the values of the information difference signal C _i as :

C _i = С ₊ -С _- = kU ₊ / U _{I +} -kU _- / U _I- = (U ₊ / I ₊ -U _- / I _- ) ⋅k / R _op ,

where U ₊ and U _- are the total signal, respectively, of positive and negative polarity, taken from the electrodes of the submersible local speed sensor at various time intervals of the measurement cycle Tism;

U ₊ = U ₀ + U _v in the time interval for the formation of a positive half-wave of the meander current through the coil t1 - when the logic control signals g1 = 1, g2 = 0 and a positive polarity current flows through the coil;

U _- = U ₀ -U _v in the time interval for the formation of a negative half period of the current meander through the coil t3 - when the logical control signals g1 = 0, g2 = 1 and a negative polarity current flows through the coil;

U ₀ is the total signal during the pause time intervals t2 and t4, when the logical control signals g1 = 0, g2 = 0 and there is no current through the coil, while the multi-channel power supply in the coil circuit does not consume electricity from the industrial network, that is, they save.

the values of the information difference signal C _i determined in the microcontroller are stored in its RAM until new values of C _{i are} received in the following measurement cycles,

the local velocity v is also measured by the measured values of the information differential signal Ci, while the nominal static characteristic of the local velocity meter obtained during its calibration is used, it is stored and stored in the memory of the microcontroller,

the results of measurements of the local velocity v of the controlled fluid in the primary signal converters are stored in the microcontroller memory for the duration of the measurement cycle T _ISM = T _g1 + T ₀ = T _g2 + T ₀ until new measurements are received in the next measurement cycle T _ISM , while the old measurements replaced by new ones, that is, the next measuring cycle begins,

then the microprocessor autonomously, regardless of the operation of the primary signal converters, in automatic mode, according to the compiled algorithm and program, reads from the microcontroller memory every second the current measured values of local speeds v ₁ , v ₂ and v ₃ at measuring points i _1,2,3 submersible sensors of local speed .

In FIG. 1a shows the composition and arrangement of blocks (devices) in the cross section of the pipeline.

In FIG. 1b shows the composition and arrangement of blocks in a longitudinal section of the pipeline.

In FIG. Figure 1c shows the measuring points of submersible local speed sensors (PDLS).

In FIG. 2a shows a simplified block diagram of a primary signal converter PPS-1, 2, 3 and a local speed meter (IS).

In FIG. 2b shows a block diagram of a device for measuring fluid flow.

In FIG. 3a shows timing diagrams of the control signals of the submersible local speed sensor.

In FIG. 3b shows time diagrams of the main information signals of a submersible local speed sensor.

In FIG. 4 shows time diagrams of volumetric flow rate, local and average velocity of the measured (controlled) fluid.

In FIG. 5 shows the results of an experimental study of the inventive device.

The device of FIG. 1a, b contains: pipeline 1, three submersible sensors of local speed 2, including a magnetic system with coils 3 and a sensing element (SE) 4 with electrodes (contacts) E1-E2 immersed in an electrically conductive liquid 5, primary signal converters (PPS 1, 2, 3).

In FIG. 1c, the cross-section of pipeline 1 shows the contour AND of the local velocity of the fluid flow, distorted by the submersible sensors of local velocity 2, the values of the local velocity v _1-3 at measuring points 1-3.

The primary signal converters (PPS 1, 2, 3) are mounted on the submersible sensors of local speed 2 from the outside relative to the pipeline 1.

The controlled conductive fluid 5 moving through the pipeline 1 enters the local area of the magnetic field created by the coils 3 by the magnetic system of submersible sensors of local speed (based on electromagnetic flowmeters) when an electric current flows through them. As a result, according to the Faraday law on electromagnetic induction, an electromotive force (EMF) is induced in it, which creates a potential difference on the electrodes E1-E2 of the sensing element 4, that is, information signals U _{± v1-3} , proportional to the local speed v _1-3 in the measurement points of submersible sensors of local speed 2 (Fig. 1C).

Before putting the device into operation, the geometric parameters are determined (see Fig. 1a): the internal diameter of the pipeline D, the diameter of the immersion part d of the local speed sensors of the DPS, the immersion depth of the sensors of the DPS h _1-3 , the distance from the inner wall of the pipeline to the measuring points Y _1-3 as Y _1-3 = h _1-3 + X _eff , where X _eff is the distance from the end of the PDLS to the measuring point. For PDLS used in the inventive device X _eff = 2 mm These geometric parameters are stored in the faculty 1, 2, 3.

In FIG. 2a, b, a block diagram of a device for measuring liquid flow rate comprises: a pipeline 1 with a measured liquid 5, an immersion local speed sensor 2 containing a coil 3 and a sensing element 4 with electrodes E1-E2, three primary signal converters PPS 1, 2, 3 ( see Fig. 2b), each of which contains (see Fig. 2a) a current driver 6 including switches K1, K2 with a switch, a current sensor 7 including a reference resistor Rop, switch 8, a high-speed analog-to-digital converter 9, microcontroller 10, preamplifier with differential social input 11. In addition, the block diagram (see Fig. 2b) contains three multi-channel DC power supply units (MBP) with separate channels 12 and 13, a WB computing unit containing a microprocessor 14, a memory unit 15, an indicator 16, a button a four-key keyboard 17 and a separate stand-alone DC power supply 18.

The power (magnetization) channel of the coils 3 consists of a current driver 6, a current sensor 7, a microcontroller 10, and an MBP with a separate channel 12.

The measuring channel of the local speed of the controlled fluid consists of a sensitive element 4 of an immersion sensor of local speed 2 with electrodes E1-E2, a pre-amplifier with differential input 11, switch 8, a high-speed ADC 9 of the microcontroller 10 and the MBP with channel 13.

The set consisting of the local speed sensor 2 and the primary signal converter connected to it is a local speed meter of the IC (see Fig. 2a).

The computing unit of the device consists of a microprocessor 14, a memory unit 15, an indicator 16, a four-key keyboard button 17, and an autonomous direct current power supply 18. The microprocessor 14 interacts with the PPS-1, 2, 3 microcontrollers 10 by polling them and issuing control commands. The operator instructs the microprocessor through the keyboard 17 and reads information from the indicator 16.

The measuring channel for the flow rate of the controlled liquid consists of the three measuring channels of local speed v _1-3 described above and a computing unit

In the blocks of the current driver 6 keys K1, K2 are an integral part of the current driver and are located inside it. Keys K1, K2 and switch 8 are contactless, logically controlled elements.

The output of the PDLS E1-E2 electrodes through the preamplifier 11, switch 8, ADC 9 is connected to the input of the microcontroller 10, and the outputs of the microcontrollers PPS-1, 2, 3 are connected to the input of the microprocessor 14 of the WB computing unit, while the microprocessor 14 is connected to the memory unit 15 , indicator 16, keyboard 17 and an autonomous power supply 18 (Fig. 2b).

The outputs of the coils 3 PDLS 2 are connected via current shapers 6 including keys K1, K2, supporting resistors Rop current sensors 7 to channels 12 of the MBP. The output of channel 12 of the MBP is connected to the negative pole of the device at point B. The control outputs g1 and g2 of the microcontroller 10 are connected to the current shaper 6 (via keys K1, K2). The control output e of the microcontroller 10 is connected to the switch 8. The control output f of the microcontroller 10 is connected to the ADC 9. The output of the current sensor 7 is connected to the input of the switch 8 ,. The output of channel 13 of the MBP is connected to the preamplifier 11, switch 8, ADC 9, microcontroller 10 at points a-d.

The control output p of the microprocessor 14 is connected to the corresponding control inputs of the microprocessors 10 (Fig. 2a) PPP 1, 2, 3 (Fig. 2b).

Information digital outputs v ' _1,2,3 microprocessors 10 PPP 1, 2, 3 are connected to the information input of microprocessor 14 (Fig. 2A. B).

The negative poles of the channels 12 and 13 of the MBP, as well as the autonomous DC power supply 18 are connected to the negative pole of the device’s common power bus at point B. The negative pole of the device’s common power bus at point B is electrically isolated from the local protective earth at point B. The protective housing of the converters primary signals at point B are connected to the local protective earth at point h.

PDLS are developed on the basis of submersible electromagnetic sensors of local speed included in the sucker of flow meters of the type RM-5-B3 for large-diameter pipelines designed and mocked up at TBN Energoservice LLC.

Preamplifiers 11 are developed on the basis of integrated circuits of the AD8221 type by Analog Devices (USA).

The device as switch 8 uses an integrated circuit type AD707 manufactured by Analog Devices (USA). As an analog-to-digital converter 9, an integrated microcircuit type AD7714 by Analog Devices (USA) is used.

The device uses a microcontroller type AT89C51R02 company Atmel (USA).

A microprocessor 14 of type Atmega 128 from Atmel (USA), a memory block 15 of type AT45DB from Atmel (USA), indicator 16 of type WH1601 from Winstar (China) are used in the device in the calculated WB block.

Current shaper 6, current sensor 7, four-button four-button keyboard 17 were developed by TBN Energoservice LLC.

Current driver 6 is developed on the basis of optocouplers ILD213 from Vishay (USA) and IRF7343 keys from IRF (USA).

The current sensor 7 is developed on the basis of a resistive divider, in which a reference precision resistor (Rop = 0.5 Ohm, power 0.25 W), as well as a passive filter based on chip resistors of type 0805 from SINETECH (Taiwan), are used.

The four-button four-button keyboard 17 is developed on the basis of the TS-A4PS-130 tact buttons from Switronic Industrial (China). The device uses a current driver and a keyboard manufactured by TBN Energoservice.

The device uses an MBP of type BP (s) -3V (channel 12: voltage 12 V, load current 0.5 A; channel 13: voltage 9 V, load current 0.3 A) manufactured by TBN Energoservice LLC.

The device uses an autonomous DC power supply 18 of the BP (i) -3V type (one channel is used for voltage 9 V, load current 0.3 A)) manufactured by TBN Energoservice LLC.

All of the above listed radio elements are known and produced in the electronics industry.

The functioning of the device (Fig. 2A, b) when determining the flow rate of electrically conductive fluid in large-diameter pipelines occurs when the pipeline 1 is completely filled with controlled electrically conductive fluid 5 (normal operation of the device). Power supplies for the device: MBP with channels 12, 13 and an autonomous DC power supply 18 are powered from an industrial AC 220 V ± 5% network with a frequency of 50 ± 1 Hz. Blocks: pre-amplifier 11, switch 8, ADC 9, microcontroller 10 are powered by channel 13 of the MBP. Shaper current 6, current sensor 7 are powered by channel 12 of the MBP. The microprocessor 14, the memory unit 15, the indicator 16 and the keyboard 17 are powered by a stand-alone DC power supply 18 (in points dz).

In the device under the control of microcontrollers 10, the information signal U _{± v} is generated from the outputs of the electrodes E1-E2 and the current signal of the coil U _I removed from the reference resistor Rop of the current sensor 7, the current through the coil is generated by the control logic signals g1, g2 generated by the microprocessor (see . (see Fig. 3a and Table 1), the information signal U _{± v} and the coil current signal U _I are digitized by the control commands f _1,2 and е supplied by the microcontroller 10 to switch 8 and ADC 9, respectively, in accordance with the algorithm and the program for the microprocessor (see table 2). The digitization of the coil current signal U _I occurs after the microcontroller 10 sends the f ₁ command to switch 8 and the e command to the ADC. The digitization of the U _{± v} signal occurs after the microcontroller 10 sends f ₂ command to switch 8 and n commands e on the ADC (see Fig. 3b and table 2).

In this case, the voltage from channel 12 of the MBP through the current sensor 7, the current shaper 6 is supplied to the input of the coils 3. The formation of the supply current of the coils I ₊ , I _- in the form of a meander (Fig. 3b) occurs when 6 rectangular logic signals g1 are fed to the input of the current shaper , g2 from the microcontroller 10 (Fig. 2a). After providing power to the coils 3 and the above blocks under the influence of a moving conductive fluid 5 on the electrodes E1-E2 of the sensing element 4 of the local speed sensor 2, an information signal U _{± v1,2,3 is induced} , which is fed to the input of the pre-amplifier 11, then matched and amplified the information signal kU _{± v} from the output of the pre-amplifier 11 through the switch 8 is fed to the input of the ADC 9. The digitized information signal kU ' _{± v} from the output of the ADC 9 is fed to the microcontroller 10.

In addition, the signal from the output of the current sensor U _I , taken from the reference resistor Rop, is fed through switch 8 to the ADC input. The digitized signal of the coil current U ' _I from the ADC output is fed to the input of the microcontroller 10.

Thus, the following digitized (digital) information signals are input to the microcontroller 10: the coil current signal U ' _I taken from the reference resistor R _op in the current sensor 7 (for any state of the keys K1, K2 of the current driver 6); amplified information signal kU ' _{± v} from the output of the preliminary amplifier 11 (Fig. 2A). These signals, that is, the current signal of the coil U ' _I and the amplified information signal kU' _{± v,} carry information on the magnitude of the local velocity v of the controlled fluid.

According to the compiled algorithm and the program for the microcontroller, the coil current signal U ' _I and the amplified information signal kU' _{± v are} processed and converted to local speed values v. The values of the local speed v are stored in the RAM of the microcontrollers 10 of the teaching staff 1, 2, 3 (Fig. 3b).

From the microprocessor 14, the logic signal p (request) is supplied to the microcontrollers 10 of the teaching staff 1, 2, 3, as a result of which the digital signal proportional to the local speed v _1,2,3 is supplied to the input of the microprocessor 14 of the microcontrollers 10 of the teaching staff 1, 2, 3 .

The microprocessor 14 of the computing unit of the WB requests every second from the microcontrollers 10 PPS 1, 2, 3 the values of local speeds v _{1,2,3 of the} controlled fluid (see Fig. 2 and Fig. 4).

The microprocessor 14 in automatic mode according to the compiled algorithm and the program for the microprocessor using digital signal values proportional to the local flow rates v1, v2 and v3 (Fig. 4) calculates the average cross-section velocity u and the volumetric flow G of the controlled fluid as the product of the average velocity and the measurement area cross-section of the pipeline minus the area of the midsection of the submersible parts of the local speed sensors.

The measurement results are stored in the RAM of the microprocessor 14 until new measurements are received in the next measurement cycle T _ISM , while the old measurements in the RAM are replaced by new ones, and according to the instructions of the microprocessor 14 are stored and stored in the memory unit 15 and displayed on the indicator 16. The process repeated. Entering parameters and controlling the device is carried out by the operator using the four-button keyboard 17.

The principle of operation of the device is based on the interaction of a moving controlled electrically conductive fluid 5 with the magnetic field of the coils 3 and consists in the following: when the pipeline 1 is filled with an electrically conductive fluid 5 using current shapers 6, alternating current coils 3 of the magnetic systems of the submersible sensors of local speed 2 are generated, creating a magnetic field in local area near the electrodes E1-E2 at the measuring points i _1,2,3 (see Fig. 1B). When fluid 5 moves in a magnetic field, an EMF is induced, inducing on the electrodes E1-E2 of the sensitive elements 4 local speed sensors 2, the signal U _{± v1,2,3 is} proportional to the local speed v _1,2,3 at the measuring points i _1,2,3 and magnetic field induction. The signals U _{± v1,2,3,} after matching and amplification by the preamplifier 11, digitized in the ADC 9 and processed in the microcontroller 10 of the teaching staff 1, 2, 3 are converted into digital information signals proportional to the local velocities of the controlled liquid v _1,2,3 . Digital signals proportional to the local velocities v1, v2 and v3 (see Fig. 2b and Fig. 4) of the measured liquid are supplied to the microprocessor 14, where according to a pre-compiled algorithm and program for the microprocessor, they are processed using the area-speed method. As a result, at the output of the microprocessor 14, the values of the average cross-section velocity u and the volumetric flow rate G of the controlled fluid are obtained

The method for determining the flow rate of electrically conductive liquid in large diameter pipelines is implemented as follows. There are two types of flowmeter designs — flowmeters with full bore flow sensors and flow meters with submersible local speed sensors. Full bore flow sensors have a magnetic system design with a magnetic field penetrating the entire cross section of the measured section of the pipeline, and this type of structure is mainly used in pipelines of small and medium diameters Dy ≤300 mm.

The local speed sensors have a magnetic system design with an electromagnetic field that fills only a limited part of the fluid flow near the sensing element with electrodes E1-E2 immersed in the measured liquid. This type of submersible sensors of local speed is mainly used in pipelines Dy ≥300 mm (Fig. 1a, b). Currently, one of the promising areas of flow metering is the creation of methods for measuring (determining) the flow rate of a conductive fluid based on submersible electromagnetic sensors of local speed using the area-speed method. In this case, the following stages of implementation of the proposed method for measuring flow are performed.

Stage 1. Calibration of local speed meters.

Calibration of local speed meters is carried out by a pouring or simulation method. In the process of calibrating the IS local speed meter (see Fig. 2a), consisting of a local speed submersible sensor and the primary signal converter of the faculty, determine the nominal static characteristic of the IS. Calibration of each IC is done autonomously. For example, in the process of calibration by the pouring method, a series of values of the reference local velocities ve in the range (0.2 ... 5) m / s are set on the pouring stand. at the measuring point of the sensor of the local speed of the verified IC. For each value of the reference local speed ve they measure the value of the information difference signal Ci (see Fig. 3b) IC. In addition, the value of the information difference signal Ci is measured at zero speed in the pipeline. The obtained values of the information difference signal Ci and the reference local speed ve are stored in the memory of the microcontroller 10 PPP. The microcontroller 10 in automatic mode, according to the compiled algorithm and the program for the microcontroller, uses the values of the information difference signal Ci and the reference local speed ve for a piecewise-linear approximation of the nominal static characteristics of the IC. The number of straight sections of the NSC set at least three.

Stage 2. Assembly and power supply of the device.

According to FIG. 1a, b, three local speed sensors 2 are installed symmetrically located along the generatrix of the pipeline 1 at angles of 120 degrees, the sensitive elements of the local speed immersion sensors are immersed inside the pipeline completely filled with electrically conductive liquid 5 to a depth h, the inner diameter of the pipeline D is measured, the measured values of h, D and value X _eff = 2 mm and a diameter d immersion used local velocity sensors administered in using the keyboard 17 and stored in the memory unit 15, a computing unit B.

In order to save energy, the device uses pulsed power supply to the coils of 3 submersible local speed sensors. From FIG. 3b, (see the current diagram I) it is seen that in the second cycle there is no current through the coil in the pause time interval T ₀ = t1 = t4 for a duration of 640 ms. It follows that the energy saving from the industrial network in the 12 MBP channel compared to continuous power is 100% ⋅ (640 ms / 1000 ms) = 64%.

Stage 3. Formation of current in the circuit of coils and digital information signals.

For the functioning of the power supply channels of coils 3, the supply voltage of 220 V, 50 Hz from the industrial network is supplied to the MBP (Fig. 2a). From the outputs of the channels 13 of the MBP feed the preamplifier 11, switch 8, ADC 9, the microcontroller 10. From the outputs of the channels 12 of the MBP feed the current shaper 6 and the current sensor 7 (reference resistor R _op ).

Thus, in the device, the power of current shapers 6 is carried out separately from the power of blocks 8-11 (Fig. 2), while eliminating the influence of the supply current of the coils on the measuring channels, which increases the accuracy of measuring local speed.

The supply current of the coils is formed regardless of the operating mode of the pipeline, that is, the fullness, speed and temperature of the flow of the controlled fluid 5. The formation of current in the coil circuit is shown in FIG. 3b (see current diagram I). The current is generated using current conditioners 6, which are switched by the logical control signals g1, g2 (Fig. 2a, Fig. 3a and table 1) generated by the microcontroller 10. The current signal of the coil U _I , proportional to the current strength, is generated in the current sensor 7 on a reference resistor R _op , which is fed to the input of the switch 8.

According to the compiled algorithm and program, the microcontroller 10 generates rectangular control logic signals g1 and g2, which are supplied to the current driver 6. The sequence of T control logic signals g1, g2 is 2 s, the signal duration is g1 = g2 = 360 ms, and the leading edge of the signal g2 shifted relative to the trailing edge of the signal g1 by the time T ₀ = 640 ms (see Fig. 3a). Using a current shaper 6, they feed the coil 3 of the magnetic system of submersible sensors of local speed with current in the form of a meander of positive and negative polarity.

During the time interval t1, the microcontroller 10 delivers the logic control signals g1 = 1 (key K1 is closed) and g2 = 0 (key K2 is open) to the current driver 6, while the current I ₊ flows through the positive polarity coil 3. In the same interval t1, after the time of establishment of the transient current Tc during the time interval T1 (see Fig. 3b, diagram I), the microcontroller 10 supplies the control signal f ₂ to switch 8 (see table 2), while through switch 8 from the output preamplifier 11 information signal kU _{± v is} fed to the input of the ADC 9 (see Fig. 2A). Thus, in the time interval T1 to the input of the ADC 9 serves an amplified signal from the electrodes kU _{+ v} . Then, the microprocessor 10 instructs e to digitize the ADC 9. In this case, the ADC 9 digitizes the signal kU _{± v} . Supplied to its input and digitally transmits the value kU ' _{+ v} . into the microcontroller 10 for processing. During the time interval T1, the microcontroller 10 repeats the e command repeatedly (for example, n = 10 times), while the digitization of the signal kU _{+ v is} repeated n times (see table 2 and Fig. 3b, diagram e and kU _{+ v} ) and n values the digitized signal kU ' _{+ v is} stored in the RAM of the microcontroller 10 for further processing. Further, during the time interval T2, the microcontroller 10 supplies the control signal f ₁ to the switch 8, while the information signal of the current sensor U _I , proportional to the current through the coil 3, from the output of the current sensor 7, taken from the reference resistor Rop is fed through the switch 8 to ADC input 9 (see Fig. 2a).

Then, the microcontroller 10 gives the command e to the ADC 9, while the ADC 9 digitizes the signal of the current sensor U _I supplied to its input and digitally transmits the measured value U ' _I. into the microprocessor for processing (see table 2 and Fig. 2A).

During the time interval t2, the duration of which is T ₀ = t2 = t4, the microcontroller 10 supplies the logic driver g1 = 0 (key K1 open) and g2 = 0 (key K2 open) to the current driver 6, the power supply circuit of coil 3 opens and there is no current through the coil (see table 1 and Fig. 3a, b).

During the interval t3, the microcontroller supplies the current driver logic control signals g1 = 0 (K1 open key) and g2 = 1 (key K2 is closed), thus through the coil 3 flows a current I _- of negative polarity (see table 1.). Then, operations similar to those in the time interval t1 are performed, - the microcontroller submits the control signals f _1,2 to the switch and the digital commands e to the ADC, respectively, resulting in a series of measurements of the signal kU _-v and the signal of the current sensor U _I during a negative pulse current through the coil 3 (see table 2 and Fig. 3b). The digitized signal of the current sensor U ' _I and n values of the digitized signal kU' _{-v are} stored in the RAM of the microcontroller 10 for further processing.

During the time interval t4, the duration of which is T ₀ = t2 = t4, the microcontroller supplies the logic driver g1 = 0 (key K1 open) and g2 = 0 (key K2 open) to the current driver, the power supply circuit of the coil opens and the current through the coil absent (see table 1 and Fig. 3a, b). The process is then repeated.

Stage 4. Improving the accuracy of measuring local speed.

The accuracy of measuring the local velocity of the controlled fluid flow is increased as follows: n values (for example, n = 10) of the digitized signal kU ' _{+ v, j} obtained in step 3 during the time interval t1 and stored in the RAM of the microcontroller 10 (j is the number of the stored values kU _{'+ v, j} from the current measurement series j = 1, ... n) is treated according to a predetermined statistical methods compiled method, implemented in a program for the microcontroller 10. in order to increase the economic efficiency of using simple statistical method tion treatment, which may be implemented in an inexpensive microprocessor used in the claimed device. For example, the averaging method with the exception of outliers, by which the maximum and minimum values of kU ' _{+ v, j are} discarded, the remaining n-2 values of kU' _{+ v, j} are averaged, while the value kU ' _{+ v} obtained after averaging is stored in the RAM of the microcontroller 10 and used in further calculations. By the indicated method, the random component of the relative error of measuring the local velocity is substantially reduced to a value from 0.1 to 0.01%.

Similar actions are used when processing n values of the digitized signal kU ' _{-v, j} obtained in stage 3 during the time interval t3 and recorded in the microcontroller's RAM.

Further, similar steps are repeated for each measurement cycle T _edited.

Stage 5. The process of forming the information differential signal.

The information difference signal Ci, proportional to the local speed of the controlled fluid, is necessary to calculate the local speed using the NLC of the local speed meter obtained in stage 1.

The information difference signal Ci is formed in the microprocessor 10.

Use the fact that the direction and magnitude of the magnetic field induction in the measuring point i ₁ of the local speed sensor 2 (see Fig. 1a-c) proportionally changes in accordance with the change in the direction and magnitude of the current through the coil 3 and does not depend on the change in the parameters of the controlled fluid 5 In this case, the information signal U _{± v} on the electrodes E1-E2 (Fig. 2) of the local speed immersion sensor 2 changes in proportion to the local speed v of the controlled electrically conductive liquid 5 and the magnitude of the magnetic field induction B at the measuring point i ₁ : U _{± v} ~ v⋅B. Since the magnitude of the induction B is proportional to the current I _± through the coil 3, then U _{± v} ~ v⋅U _I , where U _I is the signal of the current sensor of the coil 3: U _I = | R _op ⋅I _± |, where R _op [Ohm] - resistance of the reference resistor in the coil current sensor circuit. The fact that the induced voltage U _{± v} on the electrodes E1-E2 in magnitude and nature depends on the magnitude and nature of the signal of the coil current sensor U _I in the coil circuit is used. This dependence is converted to the form C = kU _{± v} / U _I , where k is the gain of the pre-amplifier 11 (Fig. 3b, diagram C), thereby eliminating the influence of the instability of the signal U _{± v} associated with the instability of the supply current of the coils and reduce the requirements to ensure the stability of the amplitude of the current pulses of the coils (see Fig. 3b, diagram C).

Considering the fact that a bias signal U ₀ arises on the electrodes E1-E2 due to the occurrence of secondary electrochemical processes on the electrodes, the signal C will be shifted by the value C ₀ = kU ₀ / U _I (see Fig. 3b, diagram C). The value of C ₀ can be positive and negative, which is explained by the heterogeneity of the material of the electrodes and the composition of the electrically conductive liquid.

This bias is eliminated as follows: the microcontroller 10 in automatic mode according to the compiled algorithm and program calculates the values of the information difference signal C _i

C _i = С ₊ -С _- = kU _{+ v} / U _I -kU _-v / U _I = (U ₊ / I ₊ -U _- / I _- ) ⋅k / R _op

wherein U ₊ and U- - sum signal, respectively positive and negative polarity, removable with electrodes E1-E2 immersion local velocity sensor at different intervals of time the measuring cycle T _MOD:

U ₊ = U ₀ + U _{+ v} in the time interval for generating positive pulses (see Fig. 3b) t1 - when the logical control signals g1 = 1, g2 = 0, the key K1 is closed, K2 is open and a positive polarity current flows through coil 3 ;

U _- = U ₀ -U _-v in the time interval for generating negative pulses (see Fig. 3b) t3 - when the logic control signals g1 = 0, g2 = 1, the key K1 is open, K2 is closed and a negative polarity current flows through coil 3 ;

U ₀ - the total signal in the time intervals pause t2 and t4, when the logical control signals g1 = 0, g2 = 0, the keys K1, K2 are open and there is no current through the coil 3.

Thus, the information difference signal C _i is a signal characterizing the local speed with improved quality, since it depends only on the local speed and its magnitude is not affected by the instability of the supply current of the coils and the bias signal U ₀ due to the occurrence of secondary electrochemical processes on the electrodes. The value of C _i is dimensionless and is obtained by performing arithmetic operations on two measured signals U _{± v} and U _I measured at different points in time, when the current through the coil has a positive and negative polarity, respectively. The difference information signal C _i is combined and is not directly related to the physics of generating information signals of local speed U _{± v} and coil current signal U _I.

For the pre-amplifier 11, the gain is k = 13.6, the reference resistance of the current sensor R _op = 0.5 Ohms. According to experimental data, at a local velocity of 1 m / s and a current through a 300 mA coil, a characteristic signal value U _{+ v} = | U _-v | = 10 μV arises at the output of the submersible local velocity sensors used in the device. For example, when the signal is shifted U ₀ = 1.25 μV, we get:

C _i = [(1.25 + 10) ⋅10 ^-6 - (1.25-10) ⋅10 ^-6 )] ⋅13.6 / (0.5⋅300⋅10 ^-3 ) = 1.81⋅10 ^-3

At zero bias U ₀ = 0 μV we get the same value C _i

C _i = [(0 + 10) ⋅10 ^-6 - (0-10) ⋅10 ^-6 )] ⋅13.6 / (0.5⋅300⋅10 ^-3 ) = 1.81⋅10 ^-3

Thus, the influence of bias U ₀ on the measurement results of the information difference signal C _{i is} excluded and the accuracy of measuring the local velocity of the controlled fluid is increased. In the above example, the offset is 10% of the useful signal. Using the method of generating a differential signal allows you to completely eliminate the component of the relative error in measuring the local speed associated with the offset U ₀ , that is, reduce it to the accuracy of digital conversions of analog signals. The inventive device uses a 24-bit ADC, so the accuracy of digital conversions is determined by the digitization step equal to 1/2 ²⁴ .

In the process of generating the information difference signal, the value kU ′ _{± v} obtained in step 4 is used, processed in microprocessor 10, and kU ′ _{± v is} measured over time T ₁ = T ₊ -T _s -T ₂ = (360-60-60 ) ms = 240 ms (see Fig. 3b, diagrams I and U _v ), where T _c is the transient time in the power supply channel of the coils, T ₂ is the time reserved for measuring the current I through coil 3 equal to T ₂ = 60 ms based on the technical characteristics of the ADC 9 used in the device, and the current value I ₊ through coil 3 is measured after kU _{+ v} , the current value I is measured after measurement kU _-v (see Fig. 3b, diagram U _v ).

Step 6. Measure local speeds.

The microcontroller 10, the nominal static characteristic of the local velocity meter determined in step 1 (calibration), from the measured values of the information difference signal C _i obtained in step 5, determines the local velocity v of the controlled fluid.

The results of measurements of the local velocity v in the teaching staff 1, 2, 3 of the controlled fluid 5 are stored in the RAM of the microcontrollers 10 during the measurement cycle time Tmiz = T _g1 + T ₀ = T _g2 + T ₀ (for example, T _meas = 1 sec, see Fig. 3b, diagrams of local velocity v) until new measurements are received in the next measuring cycle T _rev . In this case, the old measurements are replaced by new ones, that is, the next measuring cycle begins.

Step 7. Measure the average speed and flow rate.

In the device, the power supply of the WB computing unit is carried out from an autonomous DC power supply unit 18. The microprocessor 14 in automatic mode according to the compiled algorithm and the program for the microprocessor reads from the memory of microcontrollers 10 the current values of local speeds v ₁ , v ₂ and v ₃ measured in step 6 points i _1,2,3 submersible sensors of local speed (see Fig. 1C).

The average speed and the controlled fluid 5 in the measured section of the pipeline 1 (see Fig. 1A, b, c) are calculated according to the expression:

where N is the number of meters local speed; α _i - normalized velocity coefficients, v _i - local speed values at the measuring points.

The flow rate of the controlled fluid is calculated as the product of the average speed and the measuring cross-sectional area:

G _v = uS.

The measuring cross-sectional area is calculated by the formula:

S = πD ² /4-S _M ,

d - диаметр датчика скорости; h_i - глубина погружения i-го датчика локальной скорости.where: D is the internal diameter of the pipeline, S _m is the total area of midsection of the local speed sensor

d is the diameter of the speed sensor; h _i - immersion depth of the i-th local speed sensor.

For example, with the following parameter values:

D = 520 mm, d = 37 mm, Θ = 20 ° C, h ₁ = h ₂ = h ₃ = 30 mm, X _eff = 2 mm, v ₁ = v ₂ = v ₃ = 1 m / s

α ₁ = α ₂ = α ₃ = 1.0837

u = 1.0837 m / s

G = 815.55 m ³ / h

Thus, summarizing the steps 3-7, we obtain a distinctive part of the claimed invention.

During the measuring cycle T during the time intervals t1, t2, t3, t4 in the microcontroller 10, the following levels of logical control signals are set (Fig. 2a and table 1 and Fig. 3a): during the time interval for generating positive pulses t1, the levels of logical control signals g1 = 1 (the key K1 is closed, "Yes", that is, the current passes through the circuit), g2 = 0 (the key K2 is open, "No", that is, the current does not pass through the circuit); in the pause time interval t2, the levels of logical control signals g1 = 0 (K1 “No”), g2 = 0 (K2 “No”); in the interval of formation of negative pulses t3, the levels of logical control signals g1 = 0 (K1 “No”), g2 = 1 (K2 “Yes”); in the pause time interval t4, the levels of logical control signals g1 = 0 (K1 “No”), g2 = 0 (K2 “No”); accordingly, the microcontroller 10 generates logical control signals g1, g2, in the current conditioner form a positive half-period of the current waveform of the coil I ₊ for a period of time T _g1 , the induced voltage U _{± v} proportional to the local speed of the controlled fluid v is removed from the electrodes E1, E2, U _{± v} at the input of the preamplifier 11, they have a matched and amplified signal kU _{± v} at its output, digitize this signal and receive a digital signal kU ' _{± v} at the ADC output 9, then, after a pause time T ₀ = t2 = t4, form a negative the half-period of the coil current meander I _- in the period of time T _g2 , the trailing edges of the control logic signal g2, the negative half-cycle of the coil current cur rent I _- and the voltage U _{-v are} shifted relative to the leading edges of the control logic signal g1, the positive half-cycle of the coil current signal I ₊ and voltage U _{+ v} for a time T ₀ , the signals U _{± v} and U _I (the signal proportional to the current through the coil, taken from the reference resistor R _op current sensor 7) are digitized at time intervals t1 and t3, and the signal kU _{± v is} digitized in the interval of times T1 after the transient Tc time interval, then digitized signal U _I T2 reserved microcontroller time interval for measuring the current through the coil, at specified time intervals t1 and t3 micro controller respectively delivers a control signal command f ₂ on switch 8, wherein a the output of the preamplifier 11, the signal U _{± v is} supplied to the ADC input (see table 2 and FIG. 3b), then the microcontroller sends a control signal command e to be digitized repeatedly n times (for example, n = 10 times with a uniform or uneven step) to the ADC 9, n values of the digitized signal kU ' _{± v} are fed to the input of the microcontroller and stored in the microcontroller’s RAM for further processing, then the microcontroller provides a control command signal f ₁ to a switch 8, the current sensor output with the input of the ADC is fed the current sensor signal U _I (see. table 2) proportional to the current through the coil, and then delivers the microcontroller controls command signal is digitized in the ADC e 9, the digitized signal U _'I fed to the microcontroller input and stored in its memory for further processing.

The random component of the relative error of measuring the local velocity is also reduced as follows: n values of the digitized signal kU ' _{± v, j,} are received at the time intervals of the formation of positive and negative pulses t1 and t3, recorded in the RAM of the microcontroller 10, processed according to a predefined procedure implemented in the program for microcontroller 10, the averaging method is used with the exception of outliers, according to which the maximum and minimum values kU ' _{± v, j} , the remaining n -2 values kU ' _{± v, j} are averaged, while the value kU' _{± v} obtained after averaging is stored in the RAM of the microcontroller 10 and used in further calculations.

They also eliminate the influence of the instability of the signal U _{± v} associated with the instability of the supply current of the coils and simultaneously eliminate the bias signal U ₀ due to the occurrence of secondary electrochemical processes on the electrodes, for which, according to the compiled algorithm and the program for the microcontroller, the information differential values are calculated in the microcontroller 10 signal C _i

C _i = С ₊ -С _- = kU _{+ v} / U _I -kU _-v / U _I = (U ₊ / I ₊ -U _- / I _- ) ⋅k / R _op ,

wherein U ₊ and U- - sum signal, respectively positive and negative polarity, removable with electrodes E1-E2 immersion local velocity sensor at different intervals of time the measuring cycle T _edited;

U ₊ = U ₀ + U _{+ v} in the time interval for generating positive pulses t1 - when the logical control signals g1 = 1, g2 = 0, the key K1 is closed, K2 is open and a positive polarity current flows through coil 3;

U _- = U ₀ -U _-v in the time interval for generating negative pulses t3 - when the logical control signals g1 = 0, g2 = 1, the key K1 is open, K2 is closed and a negative polarity current flows through coil 3;

U ₀ - the total signal in the time intervals pause t2 and t4, when the logical control signals g1 = 0, g2 = 0, the keys K1, K2 are open and there is no current through the coil 3.

The values of the information difference signal C _i calculated in the microcontroller 10 are stored in its RAM until new values of C _{i are} received in the following measurement cycles.

The values of the local speed v are measured from the measured values of the information difference signal Ci, while using the NLC of the local speed IC meter obtained by its calibration, stored and stored in the memory of the microcontroller 10.

The results of measurements of the local velocity v in the teaching staff 1, 2, 3 of the monitored liquid 5 are stored in the operative memory of the microcontrollers 10 during the measurement cycle time T _ISM = T _g1 + T ₀ = T _g2 + T ₀ until new measurements are received in the next measurement cycle T _ISM (see Fig. 3b). In this case, the old measurements are replaced by new ones, that is, the next measuring cycle begins.

The microprocessor 14 in automatic mode according to the compiled algorithm and the program reads from the memory of the microcontrollers 10 the current measured values of the local speeds v ₁ , v ₂ and v ₃ at the measuring points i _1,2,3 submersible sensors of local speed (see Fig. 1C).

The average speed u is the volumetric flow rate of the controlled fluid G _v in the measured section of the pipeline 1 (see Fig. 1a, b, c). calculated according to step 7, this completes the measurement period T. Then, the measurement procedure is repeated repeatedly in the following measurement periods T.

Thus, the combined actions of known and unknown distinguishing features give new technical solutions, which advantageously reduces the error in measuring fluid flow, significantly reduces the energy consumption from the industrial network (by 64%) and thanks to these useful properties, the scope of the proposed invention is expanded. These new properties of the invention favorably differ from the selected analogue and prototype, determines, according to the applicant, the invention meets the criterion of "inventive step". To implement the invention, well-known materials in the field of radio electronics and the radio industry were used and affordable algorithms with software were created to determine the flow rate in an electrically conductive liquid with high accuracy (relative error of not more than 2%) in large pipelines. This circumstance, according to the applicant, allows us to conclude that the invention meets the criterion of "industrial applicability".

To improve the accuracy of measuring the flow rate of electrically conductive fluid at TBN Energoservice LLC, an experimental study was conducted on the UROKS-400 torrential installation using immersion local speed sensors.

The experiment was conducted on prototypes of a modernized flowmeter RM-5-B3, designed to measure and commercialize the volumetric and mass flow rate, volume and mass of the electrically conductive liquid in large pipelines, as well as for use in automated systems for metering, control and regulation of the amount of heat. In FIG. 5 shows the results of determining the relative error in measuring the flow rate dG obtained during the experiments. It can be seen that the relative error in measuring the flow rate dG does not exceed 2% when changing the average flow rate of the measured liquid in the range 0.4-3 ... 5 m / s, which meets the requirements of the "Methodology for the commercial metering of heat energy, coolant", approved by order of the Ministry of Construction and Housing -municipal economy of the Russian Federation dated March 17, 2014 No. 99 / PR, according to which flowmeters, including flowmeters with electromagnetic submersible sensors of local speed, must provide measurement of mass (volume) with relative tion error (E _ƒ):

class 2: E _ƒ = ± (2 + 0.02G _max / G), but not more than ± 5%, (12.7),

class 1: E _ƒ = ± (1 + 0.01G _max / G), but not more than ± 3.5%, (12.8),

where E _ƒ is the relative error of the flow meters, G _max is the maximum measured flow rate, G is the current value of the measured flow rate.

The device allows you to display on an alphanumeric indicator:

- the current value of the volumetric flow rate for each pipeline where the local speed sensors are installed, m ³ / h;

- the current value of the mass flow rate for each pipeline where local speed and temperature sensors are installed, t / h;

- volume cumulatively for each pipeline where local speed sensors are installed, m ³ ;

- mass on an accrual basis, for each pipeline where local speed and temperature sensors are installed, t;

- the current value of the temperature of the medium for each pipeline where temperature sensors are installed, ° C;

- the current value of the pressure of the medium in the pipelines for each pipeline where pressure sensors are installed, kgf / cm ² and MPa;

- current values of ambient temperature (when completing the device with appropriate sensors), ° C;

- operating time, h;

- current date and time values;

- information about the modification of the device, its settings and status.

The information indicated above can be transmitted digitally via the RS-485 interface (and together with peripheral devices and via the RS-232 interface) to a personal computer and / or to automated systems for accounting, control and regulation of the amount of heat.

The RM-5-B3 flowmeter provides archiving in non-volatile memory of the hourly, daily, monthly, weather values of the mass and volume of the monitored liquid, the values of the measured parameters of the liquid (flow, temperature), operating time, etc.

The archive depth is at least:

- hourly - 45 days;

- daily - 12 months;

- monthly - 5 years;

- weather - 32 years;

- events - 16 thousand records.

The device is powered by AC voltage from 187 to 242 V, with a frequency of 50 ± 1 Hz. The power consumption consumed by the RM-5-B3 does not exceed 60 watts.

Claims (17)

1. A method for determining the flow rate in pipelines of large diameters, in which the local speed meters of the device are calibrated by the pouring method with a completely measured portion of the pouring stand, the average velocity u of the controlled fluid in the measured portion of the pipeline is calculated according to the expression:

where N is the number of meters local speed; α _i - normalized velocity coefficients, v _i - local speed values at the measuring points; the flow rate of the controlled fluid is calculated as the product of the average velocity by the measuring cross-sectional area: G _v = u⋅S, the measuring cross-sectional area is calculated by the formula: S = πD ² /4-S _M ; where S _m - the total area of the midsection of the local speed sensors:

where d is the diameter of the speed sensor; h _i - immersion depth of the i-th local speed sensor, i = 1, 2, 3; characterized in that in the calibration mode of the local speed meters, the nominal static characteristic is determined, a series of values of the reference local velocities ve are set on the pouring bench in the measuring section at the measuring point of the submersible local speed sensor; for each value of the local velocity ve they measure the value of the information difference signal Ci of the local speed meter, and the values of the reference local velocity ve vary in the range (0.2, ..., 5) m / s, in addition, the value of the information difference signal Ci is measured at zero speed of the controlled electrically conductive liquid in the pipeline, the obtained values of the difference signal Ci and the reference velocity ve are stored and stored in the memory of the microcontroller of the primary signal converter in automatic mode asno composed of algorithms and programs; during the measuring cycle T during the time intervals t1, t2, t3, t4 in the microcontroller set the levels of logical control signals: in the time interval t1 - logical control signals g1 = 1, g2 = 0; in the time interval t2 - logical control signals g1 = 0, g2 = 0; in the time interval t3 - logical control signals g1 = 0, g2 = 1; in the time interval t4 - logical control signals g1 = 0, g2 = 0; under these conditions, respectively, the microcontroller generates logical control signals g1, g2, a positive half-period of the coil current waveform I ₊ is generated in the current driver in the time interval of the logical control signal g1 of duration T _g1 , the information signal U _{± v} proportional to the local velocity of the controlled fluid v is removed from the electrodes , it is fed to the preamplifier input and output are coordinated and amplified information signal kU _{± v,} then digitize the signal to obtain at the outlet analogous o-digital converter the digitized information signal kU _{'± v,} proportional to the local velocity v, after the pause time T ₀ = t2 form a negative half-cycle square wave current coil I _- in the time interval of the logical control signal g2 duration T _g2, wherein the trailing edges of the control logic signal, g2, negative half cycle of the meander coil current I _- Uv information signal and shifted relative to the front edge of the control logic signal g1, a positive half-cycle meander coil current I ₊ and nformatsionnogo signal U _{+ v} at the pause T ₀ = t4 = t2, while in the time intervals t1 and t3 form the positive and negative half-cycles of meander of current through the coil and a digitized amplified and coherent information signal kU _{± v} and current signal through the coil U _I, proportional to the current in this circuit, taken from the reference resistor Rop of the current sensor, and the information signal kU _{± v is} digitized in the time interval T ₁ after the transition time interval Tc is completed, then the signal proportional to the current through the coil U _I the time interval T ₂ reserved by the microcontroller for measuring current through the coil, during the intervals of formation of the positive and negative half-periods of the current meander through the coil t1 and t3, the microcontroller respectively sends a control command f ₂ to the switch, while the output of the pre-amplifier to the input of the analog-to-digital converter supplied information signal kU _{± v,} then the microcontroller delivers a control command to digitize e n times repeatedly with a uniform or irregular pitch to an analog-Dig oic converter, n kU digitized signal values' _{± v} stored in the main memory of the microcontroller for further processing, then the microcontroller supplies the switch control command f _1, and a current sensor output to the input of the ADC is fed the current U _I sensor signal and its output are the digitized signal of the current sensor through the coil U ' _I , then the microcontroller sends a control signal command e to digitize the ADC, the digitized signal of the current sensor through the coil U' _{I is} fed to the input of the microcontroller and stored in its operational memory for further processing, they also reduce the random component of the relative error of measuring the local speed: n values of the digitized information signal kU ' _{± v, j} , where j = 1, 2 ... n, are received at current time intervals through a coil of positive polarity t1 and negative polarity t3 and store them in the operational the microcontroller’s memory, it is processed according to a pre-compiled technique implemented in the program for the microcontroller using the averaging method with the exception of outliers, by which the maximum and minimum The values of the digitized information signal kU _{'± v, j,} the remaining n-2 values that averaged signal is stored in the RAM of the microcontroller and are used in subsequent calculations, they also eliminate the influence of the instability of the information signal U _{± v} associated with the instability of the supply current of the coils, and at the same time eliminate the bias signal U ₀ due to the occurrence of secondary electrochemical processes on the electrodes, in automatic mode, according to the compiled algorithm and the program for the microcontroller, determine the values of the information difference signal C _i as: C _i = С ₊ -С _- = kU ₊ / U _{I +} -kU _- / U _I- = (U ₊ / I ₊ -U _- / I _- ) ⋅k / R _op, where U ₊ and U _- are the total signal, respectively, of positive and negative polarity, taken from the electrodes of the submersible local speed sensor at various time intervals of the measurement cycle Tism; U ₊ = U ₀ + U _v in the time interval for the formation of a positive half-wave of the meander current through the coil t1, when the logical control signals g1 = 1, g2 = 0 and a current of positive polarity flows through the coil; U _- = U ₀ -U _v in the time interval for the formation of a negative half-wave of the meander current through the coil t3, when the logical control signals g1 = 0, g2 = 1 and a negative polarity current flows through the coil; U ₀ is the total signal during pause intervals t2 and t4, when the logical control signals g1 = 0, g2 = 0 and there is no current through the coil, while the multi-channel power supply in the coil circuit does not consume electricity from the industrial network, that is, it saves energy; the values of the information difference signal C _i determined in the microcontroller are stored in its RAM until new values of C _{i are} received in the following measurement cycles, the local velocity v is also measured by the measured values of the information difference signal Ci, while the nominal static characteristic of the local velocity meter obtained during its calibration is used, it is stored and stored in the memory of the microcontroller, the results of measurements of the local velocity v of the controlled fluid in the primary signal converters are stored in the microcontroller memory for the duration of the measurement cycle T _ISM = T _g1 + T ₀ = T _g2 + T ₀ until new measurements are received in the next measurement cycle T _ISM , while the old measurements replaced by new ones, that is, the next measuring cycle begins, then the microprocessor autonomously, regardless of the operation of the primary signal converters, automatically, according to the compiled algorithm and the program, reads from the microcontroller memory every second the current measured values of local speeds v ₁ , v ₂ and v ₃ at measuring points i _{1, 2, 3 of} submersible local speed sensors . 2. A device for determining the flow rate in large diameter pipelines, comprising a measuring pipeline, including three local speed meters, each of which consists of a primary signal converter and a local speed immersion sensor connected to it, including a magnetic system with coils, the immersion part of which contains a sensing element with electrodes, and immersed in a pipeline completely filled with an electrically conductive liquid, a multi-channel DC power supply unit, an autonomous unit DC power, three primary signal converters based on electromagnetic flowmeters, which contain a pre-amplifier, a switch, an analog-to-digital converter, a microcontroller, a computing unit that contains a microprocessor, a memory unit and an indicator, while the output of the electrodes through a pre-amplifier, a switch, analog a digital converter is connected to the input of the microcontroller, and the outputs of the microcontrollers are connected to the input of the microprocessor of the computing unit, the outputs are the processor is connected to the memory unit and the indicator, the output, that is, the positive pole of the autonomous DC power supply unit, is connected to the power circuits of the microprocessor, memory unit, indicator at points e, f, f, h, one of the outputs, that is, the positive pole of the multi-channel unit power supply, connected to the power circuits of the pre-amplifier, switch, analog-to-digital converter, microcontroller at points a, b, c, d, the control output f of the microcontroller is connected to the switch in order to issue control comms to it ND f1, f2, f control output of the microcontroller is connected to an analog-digital converter, the control output of the microprocessor P connected to the respective control inputs of the p transmitters microprocessors primary signals, characterized in that additionally introduced a current driver comprising keys K1, K2 to the switch; a current sensor based on a reference precision resistor and a passive filter on chip resistors, which is part of the primary signal converters and includes a reference resistor Rop; four-button push-button keyboard; moreover, in the compiled program, the values of the information difference signal Ci and the reference local velocity ve were used for piecewise linear approximation of the nominal static characteristic of the local speed meter, the number of segments of the approximation of the nominal static characteristic was set to at least three, the sensitive elements of the local speed immersion sensors are immersed inside the pipeline completely filled with an electrically conductive liquid to a depth of h _{1, 2, 3} , the internal diameter is measured tr of the pipeline D, diameters d of the immersion sensitive elements of the local speed sensors, the distance from the inner wall of the pipeline to the measuring points Y _1-3 , its value consists of the sum Y _1-3 = h _1-3 + X _eff , where X _eff is the distance from the end face of the local speed immersion sensors to the measuring point, for the local speed immersion sensors, X _eff = 2 mm, these geometric parameters are stored in the memory of the computing unit; moreover, the outputs of the coils of submersible sensors of local speed are connected through current drivers, current sensors to the outputs, that is, the positive poles of the multi-channel power supply unit of the coils, powered from an industrial AC voltage network; the output, that is, the negative pole of the multi-channel power supply unit of the coils, is connected to the negative pole of the device at point B, another output of the multi-channel power supply unit through a current sensor based on a reference precision resistor and a passive filter on chip resistors, a current driver is connected to the input of the coil, control outputs the microcontroller g1 and g2 are connected to the keys K1 and K2 of the current driver, and the output of the current sensor is connected to the input of the switch; moreover, they protect the electrode circuit and the input circuit of the preamplifier from the penetration of external electromagnetic interference, from common-mode interference and earth currents of the device, for this the common bus of the device at point B is electrically isolated from the local protective ground at point B, while the protective casings of the primary signal converters at B are connected to the local protective earth at point h; moreover, the negative poles of the separate multichannel and autonomous DC power supplies are connected to the negative pole of the device’s common power bus at point B, the negative pole of the device’s common power bus at point B is electrically isolated from the local protective earth at point B, the protective casings of the primary signal converters at B are connected to the local protective earth at point h; moreover, the microprocessor interacts with the microcontrollers of the three primary signal converters by interrogating them and issuing control commands, and the operator sends commands to the microprocessor through the four-button keyboard, reads information from the indicator, and stores it in the memory unit of the computing unit.

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