RU224296U1 - VIBRATION FLOWMETER WITH TWO STRAIGHT HIGH PRESSURE MEASURING PIPES - Google Patents

Abstract

The utility model relates to measuring technology and can be used in various industries, including the chemical, food and oil and gas industries to measure mass flow, density, pressure and temperature of the medium being measured. The technical result is an increase in the measurement accuracy of a vibrating flow meter with two straight measuring pipelines, operating on the Coriolis effect, achieved due to the fact that the straight measuring tubes mutually oscillate at a resonant frequency due to the magnetic excitation system, the oscillation frequency of the straight measuring tubes characterizes the density of the measured medium, and the phase difference between the signals of magnetic speed sensors characterizes the mass flow, while the vibration flow meter is equipped with an analogue excess pressure sensor, temperature sensors of the measuring pipeline and a casing temperature sensor, which ensures the necessary accuracy of measurement of all required parameters for calculating flow and the ability to compensate for the influence of temperatures and pressure when measuring density and mass flow of the measured medium, at the same time, the presence of a controller ensures synchronous operation of all elements of the device. The declared layout of all sensors ensures their location as close as possible to the measurement points, which contributes to the high speed of receiving and transmitting information to the controller and also affects the achievement of the stated technical result. 7 salary f-ly, 4 ill.

Description

The utility model relates to measuring technology and can be used in various industries, including the chemical, food and oil and gas industries to measure mass flow, density, pressure and temperature of the measured medium [G01F 1/84, G01F 1/34, G01F 1/66 , G01F 15/18, E21B 41/00].

A mass flow meter operating on the Coriolis principle [US 4768384 (A) -1988-09-06] is known from the prior art, in which the problem of compensating for thermal expansion is solved by installing two temperature sensors: one of the sensors is installed on the measuring pipeline, the second - on the oscillating system . Compensation of the measured parameters is carried out by entering the coefficient K, which is calculated as

.

The disadvantage of this method is that it is applicable in a limited temperature range on a relatively smooth section of the temperature characteristic, in which the magnitude of the compensation error is acceptable. In addition, there is difficulty in determining the coefficients k ₀ -k ₅ . In practice, it is difficult to select coefficients in such a way that the overall correction factor K provides an acceptable measurement error at all possible temperatures of the measuring pipeline and casing.

Also known from the prior art is a Bridge-Type Diaphragm Plate Flowmeter [CN 219455181 (U) - 2023-08-01], which relates to the bridge-type diaphragm flowmeter technology and discloses a bridge-type diaphragm flowmeter that includes a bridge-type diaphragm flowmeter body , the lower part of the bridge type diaphragm flowmeter body is connected to the measuring pipeline, and the left and right sides of the measuring pipeline are connected to the flow pipelines through flanges. The outer ring is rigidly connected to the inner wall of the flow pipeline, a plurality of vibration guide springs are rigidly connected to the inner wall of the outer ring, connecting plates are rigidly connected to the ends remote from the outer ring, vibration guide springs and damping shock absorbers are rigidly connected to the ends of the connecting plates remote from the vibration guide springs; the ends remote from the connecting plates of the damping shock absorbers are rigidly connected to the inner rings, the upper and lower sides of the inner wall of the measuring pipeline are each rigidly connected to two fastening plates, and the side ones are behind each other, each of the two fixing plates on the right side and of the two The fixing plates on the left side are rigidly connected using a buffer spring. The bridge type diaphragm flow meter provides full effective shock absorption. The disadvantage of this analogue is low technical reliability, design complexity and low measurement accuracy.

The closest in technical essence is Compensation of thermal stresses in a vibrating flowmeter made of a curved tube [RU 2013115749 (A) - 2014-10-20], which involves equipping the vibrating flowmeter with one or many resistive casing temperature sensors Tcase and a pipeline sensor T _tube . And it assumes “a linear relationship between the temperature difference and the error of the squared period of the pipeline,” which can be determined by “a constant of proportionality (K) using thermal calibration.” In addition, temperature compensation of the flow metering pipeline module is provided. Thus, the compensation equation may contain

.

The first compensation term K1*Ttube corresponds to the compensation of the elastic modulus of the flow meter pipe or pipes. The second compensation term K2*(T _tube -T _case ) corresponds to compensation of thermal stresses. The disadvantage of this method is the linear compensation function for changes in the elastic modulus of the measuring pipeline. The dependence of the elastic modulus on temperature for various materials is not linear. When a vibrating flowmeter uses different piping and casing materials, the temperature response can be complex and unpredictable. The nonlinear change in the volume of the measuring pipeline depending on temperature is also not taken into account. As the volume of the measuring pipeline changes, the mass of the measured medium increases, which leads to a change in the oscillation frequency and therefore requires compensation.

The purpose of this utility model is to eliminate the shortcomings of analogues and prototypes.

The technical result consists in increasing the accuracy of measurements with a vibration flow meter.

The claimed technical result is achieved due to the fact that a vibrating flow meter contains two measuring tubes placed in a casing, fixed relative to each other on each side, two flow dividers are located at the ends of the measuring tubes, two magnetic speed sensors are mounted to the measuring tubes, located at equal away from the center of the measuring pipes and a magnetic oscillation excitation system located in the center of the measuring pipes, the first temperature sensor is mounted to the flow meter casing, with the ability to measure its temperature, the second sensor is mounted in the measuring tube, with the ability to measure its temperature, the excess pressure sensor is mounted in the pipeline in series with the vibration flow meter, an excess pressure sensor, magnetic speed sensors, a magnetic oscillation excitation system and temperature sensors are connected to a controller configured to compensate for the influence of temperatures and pressure when measuring the density and mass flow of the measured medium.

In particular, the measuring tubes are fixed relative to each other by means of end plates.

In particular, the measuring tubes are made straight.

In particular, magnetic speed sensors are mounted on measuring tubes at an equal distance from the center.

In particular, the magnetic excitation system is mounted in the center of the measuring tubes.

In particular, the first temperature sensor is mounted on the flow meter housing.

In particular, the excess pressure sensor is mounted in the pipeline in series with the vibration flow meter through an adapter and connected to the controller via a cable.

In particular, temperature sensors are digital.

Brief description of drawings

Fig. 1. Longitudinal section of a vibrating flow meter

Fig. 2. Vibration flow meter assembled with excess pressure sensor

Fig. 3. General view of the flow meter

Fig. 4. Practical use of the flow meter

In fig. 1, 2 show: 1 - casing, 2 - straight measuring tube, 3 - end plate, 4 - flow divider, 5 - magnetic speed sensors, 6 - magnetic oscillation excitation system, 7 - first digital temperature sensor, 8 - second digital sensor temperature, 9 - analog gauge pressure sensor, 10 - adapter, 11 - controller, 12 - RS485 serial interface.

Implementation of a utility model

A vibration flow meter containing a casing 1 (Fig. 1), two straight measuring tubes 2, secured by a pair of end plates 3 on each side, necessary to cut off the vibrations of the pipeline 2 from the rest of the vibration flow meter and the connected pipeline, as well as to cut off the vibration of the casing 1 and the connected pipeline from the measuring tubes 2. Two flow dividers 4 are located at the ends of the measuring pipelines. Magnetic speed sensors 5 are mounted on the measuring tubes 2, located at an equal distance from the center, and a magnetic oscillation excitation system 6, located in the center on the measuring tubes 2. On the right measuring tube 2, the first digital temperature sensor 7, the second digital temperature sensor are located in the center 8 on casing 1.

The analog overpressure sensor 9 is mounted in the pipeline in series with the vibration flow meter through adapter 10. The analog overpressure sensor 9 is connected to connector X1 on the instrument compartment via a 4-20mA interface and is then connected to the controller 11, which is located in the instrument compartment. Also, magnetic speed sensors 5, magnetic oscillation excitation system 6 and temperature sensors 7, 8 are connected to controller 11.

The utility model is used as follows

During operation of the product, controller 11 controls the frequency and amplitude of the swing of the measuring tubes 2 (Fig. 1), records the vibration speed of the measuring tubes 2 and calculates the phase difference of the signals of the speed sensors 5, records the temperature of the measuring tubes, the temperature of the casing and the pressure of the measured medium, and compensates for the influence temperatures and pressure when measuring the density and mass flow of the measured medium. Controller 11 is equipped with a serial interface RS485 12 (connector X2) (Fig. 2) for connecting to a vibration flow meter of a recorder, computer, display unit, radio modem or adapter of analog signals 4-20 mA and 0-10 V.

The operating principle of a vibrating flow meter is based on the Coriolis effect.

The flow of the measured liquid is cut by a flow divider 4 (Fig. 1) into two identical measuring tubes 2, and at the outlet of the tubes it is combined by a second flow divider. The measuring tubes 2 swing mutually due to the magnetic vibration excitation system 6 located in the center of the measuring tubes 2. The frequency and amplitude of the vibration excitation is controlled by the controller 11 (Fig. 2). Two magnetic speed sensors 5 located on measuring tubes 2 generate an EMF. The received signal is converted by controller 11 into amplitude and phase. The oscillation frequency of the measuring tubes 2 is determined by the phase-locked loop algorithm so that the difference in the phases of the excitation and speed sensors remains constant. In this case, the phase difference is adjusted so that the excitation frequency coincides with the resonant frequency of vibration of the measuring tubes. The oscillation frequency of the measuring tubes 2 characterizes the density of the flowing liquid; the measured density is calculated and compensated in accordance with the methodology described below.

The flow of the measured liquid, flowing through the measuring tubes 2, creates a Coriolis force, which, resisting the vibrations of the tubes, changes their phase. The phase shift of the oscillations of the measuring tubes 2, caused by the flow of the flowing liquid, is directly proportional to the mass flow. The phase difference of the speed sensors 5 is converted by the controller 11 into mass flow. Calculation and compensation of the measured mass flow is carried out in accordance with the methodology described below.

In this useful model of a vibrating flow meter, a radial basis function (hereinafter referred to as RBF) is used for the overall temperature compensation of the main measured parameters from the casing temperature y and the measuring pipeline temperature x.

To compensate for the influence of the casing temperature and the temperature of the measuring pipeline when measuring density, the compensation function has the form:

,

,

where r _i is the distance from the i-th reference point to the current surface point;

x - current value of the temperature of the measuring pipeline Tt _ube ;

x _i is the temperature value of the measuring pipeline T _tube of the reference point;

y - current value of the casing temperature T _case ;

y _i is the temperature value of the casing Ttube of the reference point;

λ _i is the coefficient of influence of the RBF of the i-th reference point on the current surface point.

Linear polynomial:

a ₀ - offset;

a ₁ - coefficient - the angle of inclination of the surface around the X axis;

a ₂ - coefficient - the angle of inclination of the surface around the Y axis;

φ (r _i ) - RBF of the i-th reference point, various RBFs can be used, in this vibrating flow meter a thin spline plate is used

.

The use of the radial basis function allows the use of empirically obtained data, pipeline temperature T _tube , casing temperature T _case as RBF reference points.

A number of measurements of the frequency of the measuring pipeline are carried out at different temperatures of the measuring pipeline Ttube and Tcase at a constant environment and at zero excess pressure of the measured medium with which the measuring pipeline is filled. All measurements are made within the temperature range of the intended operation of the vibrating flowmeter, with maximum coverage of the temperature extremes of the operating range.

A set of linear spline coefficients a ₀ , a ₁ and a ₂ and RBF influence coefficients λ _i is calculated by solving a system of linear equations

,

,

where x _i is the temperature of the measuring T _tube pipeline in the i-th frequency measurement;

y _i is the temperature of the casing T _case in the i-th frequency dimension;

ƒ _i - measured frequency.

Compensation for the influence of housing temperature and measuring line temperature when measuring density

,

where ƒ is the measured frequency;

F _CompDens - function to compensate for the influence of temperature expansion of a vibrating flow meter when calculating the density of the measured medium;

ρ ' - density of the measured medium compensated for temperature expansion (at zero excess pressure);

F _DensFreq is a function of the dependence of the measured density of the medium on the ratio of the compensated frequency of the measuring pipeline to the measured one.

The density calculation function F _DensFreq( k ₎ can be implemented by linear interpolation from experimental data

,

where ρ _i , ρ _i-1 is a set of experimental data of measured densities of the medium;

_ki, k _i-1 - a set of coefficients calculated as the ratio of F _CompDens (T _tube , T _case ) to the measured frequency.

To apply the linear interpolation function, the set of experimental data of the coefficients k _i and the corresponding densities ρ _i must be sorted in descending order by the coefficients.

However, the influence of temperatures in a vibrating flow meter not only affects the frequency of the measuring pipeline, but also the difference in the oscillation phases of the measuring pipeline. And the difference in the measured phases in a vibration flow meter characterizes the current mass flow. Therefore, in addition to compensating for the influence of temperature when calculating density, it is also necessary to compensate for the measured phase difference P _diff when calculating mass flow. To calculate the mass flow rate, it should be taken into account that in the absence of a flow of the measured medium, the phase difference P _diff has a non-zero value and must also be compensated

,

where Q _m is the mass flow rate of the measured medium;

F _Pdiff - function of the final conversion of the compensated phase difference into mass flow;

P _diff - measured phase difference;

x - temperature of the measuring pipeline T _tube;

y is the temperature of the vibration flow meter casing;

F _compDiff0 - function for compensating the influence of temperatures on phase shifts in the absence of flow.

F _compPdiff - compensation function for the influence of temperatures on the phase shift.

The phase shift compensation function F _compDiff0 and the final phase shift compensation function F _compPdiff are based on the RBF radial basis function as is the function F _compDens

,

,

,

,

where r _i is the distance from the i-th reference point to the current surface point;

x - current value of the temperature of the measuring pipeline T _tube;

x _i is the temperature value of the measuring pipeline T _tube of the reference point;

y - current value of the casing temperature T _case;

y _i - temperature value of the casing T _tube of the reference point;

β _i ,ω _i - coefficients of influence of the RBF of the i-th reference point on the current surface point.

Linear polynomials:

b ₀ , c ₀ - offset;

b ₁ , c ₁ - coefficient - the angle of inclination of the surface around the X axis;

b ₂ , c ₂ - coefficient - the angle of inclination of the surface around the Y axis.

A certain number of measurements of the phase shift of the measuring pipeline are carried out at different temperatures of the measuring pipeline T _tube and T _case with virtually no flow rate of the measured medium Q _m =0, which fills the measuring pipeline. All measurements are made within the temperature range of the intended operation of the vibrating flowmeter, with maximum coverage of the temperature extremes of the operating range.

A set of linear spline coefficients b ₀ , b ₁ and b ₂ and RBF influence coefficients β _i is calculated by solving a system of linear equations:

,

,

,

where x _i is the temperature of the measuring T _tube pipeline in the i-th frequency measurement;

y _i is the temperature of the casing T _case in the i-th frequency dimension;

P _{diff_i} - measured phase difference.

Compensated phase difference P _compDiff0

.

After compensation of the phase shift in the absence of flow, a number of measurements of the phase shift of the measuring pipeline are made at different temperatures of the measuring pipeline T _tube and T _case at a constant flow rate of the measured medium Q _m = Q _mConst , which fills the measuring pipeline. All measurements are made within the temperature range of the intended operation of the vibrating flowmeter, with maximum coverage of the temperature extremes of the operating range. For each measurement, the coefficient K _flow is calculated:

.

A set of linear spline coefficients c ₀ , c ₁ and c ₂ and RBF influence coefficients β _i is calculated by solving a system of linear equations

.

The final conversion function of the compensated phase difference into mass flow F _Pdiff can be implemented by linear interpolation from experimental data

,

where Q _mi , Q _mi-1 is a set of experimental data of measured mass flow rates of the medium;

P _{compDiff_i} , P _{compDiff_i-1} - a set of compensated phase differences corresponding to the mass flow Q _mi , Q _mi-1 .

To apply the linear interpolation function, the experimental data set must be sorted in descending order by the compensated phase difference P _{compDiff_i} .

The function of compensation for the influence of temperature on the measurement of the main measured parameters used in this utility model allows the use of data obtained empirically. The weighting coefficients of the radial basis function of the reference points are determined by solving a system of equations. In this case, all reference points of the function exactly repeat the previously measured experimental data: the frequency of the measuring pipeline to compensate for density, phase difference of the measuring pipeline in the absence of flow of the measured medium and the coefficient calculated to compensate for mass flow . The advantage of this compensation method is

exact repetitions of the function of all reference points obtained experimentally;

smooth characteristic of the function;

the ability of this compensation function to describe a complex characteristic;

To compensate for the influence of pressure when measuring density, this useful model of a vibrating flow meter uses the function :

,

where P is the pressure of the measured medium;

ρ' - density compensated for the influence of temperatures of the casing and measuring pipeline at zero excess pressure;

- function of compensation of density from the pressure of the measured medium.

Density compensation function based on the pressure of the measured medium can be implemented by linear interpolation from experimental data:

,

where k _i , k _i-1 is a set of coefficients obtained through the relation

,

where ρ _i is the actual density of the measured medium;

ρ' _i - density measured at excess pressure and compensated for the influence of temperatures;

P _i , P _i-1 - a set of experimental data on pressure in the i-th dimension of density ρ' _i .

To apply the linear interpolation function, the experimental data set must be sorted in descending order by the pressure of the measured medium.

The technical result is an increase in the measurement accuracy of a vibration flow meter, with two straight measuring pipelines, operating on the Coriolis effect, achieved due to the fact that the straight measuring tubes 2 mutually oscillate at a resonant frequency due to the magnetic excitation system 6, the oscillation frequency of the straight measuring tubes 2 characterizes the density of the measured environment, and the phase difference between the signals from magnetic speed sensors 5 characterizes the mass flow. In this case, the vibration flow meter is equipped with an analogue excess pressure sensor 9, temperature sensors of the measuring pipeline 7 and a casing temperature sensor 8, which ensures the necessary accuracy of measurement of all the required parameters for calculating flow and the ability to compensate for the influence of temperatures and pressure when measuring the density and mass flow of the measured medium. At the same time, the presence of controller 11 ensures synchronous operation of all elements of the device. The declared layout of all sensors ensures their location as close as possible to the measurement points, which contributes to the high speed of receiving and transmitting information to the controller 11 and also affects the achievement of the stated technical result.

Implementation example

The proposed technical solution was implemented in 2023. The created technological installation made it possible to increase the accuracy of measuring the flow rate of liquids pumped through it by 20-30% compared to solutions known from the prior art and to simplify the technology for estimating the volume of pumped liquids (Fig. 4)

Claims (8)

1. A vibration flow meter containing two measuring tubes placed in a casing, fixed relative to each other on each side, two flow dividers are located at the ends of the measuring tubes, two magnetic speed sensors are mounted to the measuring tubes, located at an equal distance from the center of the measuring tubes, and magnetic oscillation excitation system located in the center of the measuring tubes, the first temperature sensor is mounted to the flow meter casing with the ability to measure its temperature, the second sensor is mounted in the measuring tube with the ability to measure its temperature, the excess pressure sensor is mounted in the pipeline in series with the vibration flow meter, the excess pressure sensor, magnetic speed sensors, a magnetic oscillation excitation system and temperature sensors are connected to a controller configured to compensate for the influence of temperatures and pressure when measuring the density and mass flow of the medium being measured. 2. Vibrating flow meter according to claim 1, characterized in that the measuring tubes are fixed relative to each other using end plates. 3. Vibrating flow meter according to claim 1, characterized in that the measuring tubes are straight. 4. Vibration flow meter according to claim 1, characterized in that magnetic speed sensors are mounted on measuring tubes at an equal distance from the center. 5. Vibrating flow meter according to claim 1, characterized in that the magnetic excitation system is mounted in the center of the measuring tubes. 6. The vibration flow meter according to claim 1, characterized in that the first temperature sensor is mounted on the flow meter casing. 7. The vibration flow meter according to claim 1, characterized in that the excess pressure sensor is mounted in the pipeline in series with the vibration flow meter through an adapter and connected to the controller via a cable. 8. Vibration flow meter according to claim 1, characterized in that the temperature sensors are digital.