RU2772234C1 - Unit for calibration and verification of gas flow measurement equipment - Google Patents

Abstract

FIELD: measuring.

SUBSTANCE: invention relates to the field of measurements and testing, namely, to verification units for calibration and verification of meters, flow meters, and gas flow meters on sonic nozzles. Unit for calibration and verification of gas flow measurement equipment comprises sonic nozzles with shutoff valves, a pump, a receiver, and a control module. For calibration or verification of the apparatus, verification points for gas flow are therein set in the control module, wherein for each of said points, sonic nozzles included in the flow rate formation are determined, the nominal flow rates d_i whereof are expressed as powers of two and represented by an n-bit binary number, wherein the total flow rate of the apparatus is formed in the form of the sum of the flow rates of the sonic nozzles with binary weights

, where a_k is a coefficient with the values 0 or 1 accounting for the participation of the sonic nozzle in the flow rate formation, wherein a_k=0 if the sonic nozzle is excluded from the flow rate formation (disabled), and a_k=1 if the sonic nozzle is included in the flow rate formation, sensors for measuring the temperature and pressure of the verification medium in the receiver, temperature, pressure and humidity of ambient air are connected to the controller to be used for measuring the parameters of the verification medium pumped through the sonic nozzles and the environment to determine the volume of the verification medium pumped through the gas flow measurement apparatus and the relative error of the unit in the control module.

EFFECT: increase in the reliability of the unit for calibration and verification of gas flow measurement equipment.

4 cl, 1 tbl, 1 dwg

Description

The invention relates to the field of measurement and testing, and in particular to verification facilities for verification and calibration of meters, flow meters and gas flow meters on critical nozzles [G01F 25/00].

Known from the prior art is the METHOD FOR COUNTER CALIBRATION USING SOUND NOZZLES [CN 112268601 (A), publ.: 01/26/2021], characterized in that the data acquisition unit is installed on the measuring table with sonic nozzles, the meter number is entered through the scanning reader and the data is recorded meter to the data acquisition unit, supply power to the meter through the data acquisition unit, turn on the measuring table with sonic nozzles and determine the data of the instantaneous flow rate of the meter through the data acquisition unit, compare it with the gas flow rate actually emitted by the sonic nozzle and obtain the meter error.

The disadvantage of the analog is the insufficiency of disclosing its essence (essential features).

Also known is an INSTALLATION FOR CHECKING AND CALIBRATION OF GAS METERS [RU 9067 U1, publ.: 01/16/1999], containing a housing, a mechanism for connecting to a measuring line, an exemplary flow meter with nozzles placed on the base, an input for the flow of the measured medium, a blower that creates a vacuum , a device for maintaining the required flow rate for each nozzle, characterized in that the installation is equipped with pressure sensors, a thermometer, a barometer, units: power supply, registration and calculation control, while the body is made with a hinged lid containing mounting elements, and the mechanism for connecting to the measuring the line is equipped with a "line-atmosphere" bypass valve, and the base of the exemplary flowmeter with nozzles is installed hermetically through a spring-loaded intermediate disk between the posts rigidly fixed in the housing, while the intermediate disk is equipped with a squeezing mechanism, and the inlet for the flow of the medium being measured is made in the form of a straight pipe section , one end is rigidly connected with an intermediate disk, and at the other end movably connected to the "line-atmosphere" bypass valve.

The disadvantages of analogues are the low reliability of the installation and high labor costs for its manufacture, due to the presence of reference flow meters in the installation, which, as an option, are reference meters that complicate and increase the cost of the installation.

The closest in technical essence is the INSTALLATION FOR VERIFICATION AND CALIBRATION OF COUNTERS, FLOW METER AND FLOW METER-GAS METER [RU 2533329, publ.: 20.11.2014], containing standard flow meters - critical nozzles, each of which is equipped with a shut-off valve, pump, receiver ( forechamber), a monitoring and control system containing a block for controlling shut-off valves, characterized in that a block for forming a set of critical nozzles according to a given value of the flow rate of the calibration medium is additionally introduced into the monitoring and control system.

The main technical problem of the prototype is an involuntary set of critical nozzles used in the installation, which complicates the industrial applicability of this technical solution, since a constantly changing set of nozzles, firstly, increases the material consumption of the installation itself and makes it difficult to use it in non-stationary conditions, and secondly, the need to replace critical nozzles entails a decrease in the reliability of the installation and its accuracy; thirdly, a decrease in the reliability of the installation and its accuracy is associated, among other things, with uncontrolled contamination of critical nozzles during operation of the installation.

The objective of the invention is to eliminate the disadvantages of the prototype.

The technical result of the invention is to increase the reliability of the installation for calibration and verification of gas flow measurement devices.

, где a_k – коэффициент со значениями 0 или 1, учитывающий участие критического сопла в формировании расхода, при этом а_k=0, если критическое сопло исключено из формирования расхода (выключено) и а_k=1, если критическое сопло включено в формирование расхода, к контроллеру подключены датчики измерения температуры и давления поверочной среды в ресивере, температуры, давления и влажности окружающего воздуха для измерения с их помощью параметров поверочной среды, прокачиваемой через критические сопла и окружающей среды для определения в модуле управления объема поверочной среды, прокачанной через устройство измерения расхода газа и относительной погрешности установки.The specified technical result is achieved due to the fact that the installation for calibration and verification of gas flow measurement devices, containing critical nozzles with shut-off valves, a pump, a receiver and a control module, characterized in that calibration points for flow are set in the control module for calibration or verification of the device gas, for each of which the critical nozzles included in the formation of the flow rate are determined, the nominal flow rates d _i of which are expressed as powers of two and represented by an n-bit binary number, while the total flow rate of the device is formed as the sum of the flow rates of critical nozzles with binary weights

, where a _k is a coefficient with values of 0 or 1, taking into account the participation of the critical nozzle in flow formation, while a _k = 0 if the critical nozzle is excluded from the flow formation (disabled) and a _k = 1 if the critical nozzle is included in the flow formation , sensors are connected to the controller to measure the temperature and pressure of the test medium in the receiver, the temperature, pressure and humidity of the ambient air to measure the parameters of the test medium pumped through the critical nozzles and the environment to determine the volume of the test medium pumped through the measuring device in the control module gas flow rate and relative installation error.

, первое из которых выбирается из ряда 0,004, 0,008, 0,016, 0,032, 0,064 м³/час.In particular, the flow rate of each of the critical nozzles is determined as

, the first of which is selected from a range of 0.004, 0.008, 0.016, 0.032, 0.064 m ³ /hour.

, где ΔP – перепад давлений между входом в критическое сопло и атмосферой, P_атм – атмосферное давление воздуха, измеряемое датчиком атмосферного давления, К – градуировочный коэффициент критического сопла, К_tφ – коэффициент зависимости «температура – влажность».In particular, the volume of the calibration medium is defined as

, where ΔP is the pressure difference between the inlet to the critical nozzle and the atmosphere, P _atm is the atmospheric air pressure measured by the atmospheric pressure sensor, K is the calibration coefficient of the critical nozzle, K _tφ is the temperature-humidity dependence coefficient.

In particular, the pressure difference between the critical nozzle inlet and the atmosphere is measured by a differential pressure sensor connected downstream of the gas flow measurement device.

The figure shows a block diagram of the installation for calibration and verification of gas flow measurement devices, which indicates: 1 - critical nozzles, 2 - valves, 3 - receivers, 4 - pumps, 5 - gas flow measurement device, 6 - absolute pressure sensor, 7 – gas temperature sensor, 8 – differential pressure sensor, 9 – controller, 10 – air temperature sensor, 11 – ambient air pressure sensor, 12 – air humidity sensor, 13 – control module.

Implementation of the invention.

The installation for calibration and verification of gas flow measurement devices contains reference gas flow meters made in the form of critical nozzles 1. The principle of operation of the installation is based on reproducing and measuring the speed of movement of the calibration medium, for example, air through critical nozzles 1 in critical mode. The speed of movement in this mode is constant, therefore, with a known value of the diameter of the critical nozzle 1 and the parameters of the external environment (temperature, pressure, humidity), the air flow is calculated, and with the measured value of time, the volume is calculated. The calculated flow rate and volume values are further used as reference values.

Each of the critical nozzles 1 is provided with a controllable valve 2. Critical nozzles 1 on one side are connected by a common line through receivers 3 to pumps 4. Pumps 4 are made, for example, vacuum. On the other hand, a gas flow measurement device 5, for example, a counter, or a flow meter, or a flow meter, etc., is connected to the critical nozzles 1, along another line.

An absolute pressure sensor 6 is connected to the line between valves 2 and receivers 3, and a gas temperature sensor 7 is connected to one of the receivers 3.

A differential pressure sensor 8 is connected to the line between the critical nozzles 1 and the gas flow measurement device 5.

Valves 2, absolute pressure sensors 6, gas temperature 7 and differential pressure 8 are connected to the controller 9.

An air temperature sensor 9, a relative pressure sensor 10, and an air humidity sensor 11 are also connected to the inputs of the controller 9.

The controller 9 is configured to convert the measured signals from sensors 6-8 and 9-11 into digital signals, calculate the gas flow and volume, control the critical mode of nozzles 1, control valves 2 and pumps 4.

The controller 9 is connected to the control module 13, made in the form of a PC, laptop, tablet, smartphone, etc. with the ability to input / output information, control the controller 9, select operating modes and monitor the performance of the installation as a whole.

The installation calculates the volumetric (mass) flow rate, volume (mass) of the calibration medium passed through the gas flow measurement device 5, recalculates to standard conditions in accordance with GOST Ρ 8.740-2011 and determines the error of the said device 5.

The installation for calibration and verification of gas flow measurement devices is used as follows.

Before calibration, a gas flow measurement device 5 is connected to the inlet of a common line with critical nozzles 1.

A new essential feature in the technical solution that ensures the achievement of the claimed technical result - an increase in the reliability of the installation, is that the set of critical nozzles 1 for calibrating and verifying a line of gas flow measurement devices is unchanged, while the nominal flow rates of the critical nozzles 1 are chosen as powers of two and represent n -bit binary number.

The flow rate Q _i of each of the critical nozzles 1 in the installation is determined by the formula:

(1),

(one),

the first of which is selected from a range of 0.004, 0.008, 0.016, 0.032 and 0.064 m ³ /hour, depending on the flow measurement range of the calibrated devices. For example, for flow measurement in the range from 0.016 to 16 m ³ /h, the installation includes 10 critical nozzles 1 with flow rates of 0.016, 0.032, 0.064, 0.128, 0.256, 0.512, 1, 2, 4 and 8 m ³ /h. Any flow rate in the range from 0.016 to 16 m ³ is represented in this case by a 10-bit binary number.

To increase the flow measurement range, the number of nozzles is increased, while the flow rate of each of the added critical nozzles 1 is also determined by formula 1.

The sum of the flow rates is formed as the sum of the flow rates of nozzles 1 with binary weights according to the formula:

(2)

(2)

where Q is the flow rate of device 5, m ³ /hour;

k is the number of critical nozzles 1;

d is the minimum flow rate of the critical nozzle 1;

a _k is a coefficient with values of 0 or 1, taking into account the participation of critical nozzle 1 in flow formation, and _k = 0 if critical nozzle 1 is excluded from flow formation (disabled), and _k = 1, if enabled.

In the control module 13, the data of the calibrated gas flow measurement device 5 and the calibration points for the flow are set. For example, for device 5, size G1.6, the flow test points would be 0.016, 1.6 and 2.5 ^m3 /h.

The critical nozzles 1 included in the formation of the flow rate are determined by formula 2, for which, knowing the calibration point for the flow rate Q (the left side of the formula 2) and the minimum flow rate of the critical nozzle 1 in the installation d (the first multiplier of the right side of the formula 2), the second multiplier of the right side of the formula 2 is determined .

Since the first calibration point Q = 0.016 m ³ /h, and the minimum flow rate of the critical nozzle 1 in the installation is also equal to 0.016, then only this critical nozzle 1 will participate in the flow formation.

For the second calibration point Q = 1.6 m ³ / h, the second multiplier on the right side of formula 2 will be equal to Q / d = 1.6 / 0.016 = 100. The resulting value is converted from decimal to binary: 1100100. Each of the digits of the received code is the coefficient a _k from formula 2, which determines the participation of the critical nozzle 1 in the formation of the flow. Thus, based on the code, the flow rate includes (from right to left) the third, sixth and seventh critical nozzles 1 with flow rates of 0.064, 0.512 and 1.024 m ³ /h, respectively (sum 1.590 m ³ /h).

For the third calibration point Q = 2.5 m ³ /h, the second multiplier on the right side of formula 2 will be equal to Q / d = 2.5 / 0.016 = 156.25. The integer number of the obtained value is converted from the decimal number system to binary: 10011100. Based on the code, the third, fourth, fifth and eighth critical nozzles 1 are included (from right to left) with flow rates of 0.064, 0.128, 0.256, 2.048 m ³ /hour, respectively ( the sum is 2.496 m ³ /hour).

The device for measuring gas flow 5 is calibrated in turn at each of the given calibration point for gas flow, for which, before starting calibration, valves 2 of nozzles 1 are opened, participating in the formation of flow and determined by formula 2. After opening valves 2, pumps 4 are turned on, with the help of which a critical pressure drop across the open critical nozzles 1 and air is pumped for time t through the gas flow measurement device 5.

In the process of pumping air, the temperature of the pumped calibration medium in the receiver 3 is measured using a gas temperature sensor 7, the ambient air temperature using an air temperature sensor 11, the relative air pressure using an atmospheric air pressure sensor 11 and the air humidity using a humidity sensor 12 and transmitting the measured values to controller 9.

The gas flow rate through each of the critical nozzles 1 is determined in the control unit 13 by the known area of the throat of said nozzle 1 and the measured gas temperature according to the formula:

, (3)

, (3)

where Q ₀ - volumetric air flow, m ³ / h;

K - calibration coefficient of the critical nozzle 1, m ³ / hour (K ^0.5 ), determined for an ambient temperature of + 20 ° C and a humidity of 60%;

T ₀ - absolute temperature of the working environment, K, T ₀ = t + 273.15.

At a constant temperature of the working medium, the volume flow remains constant, therefore, the estimated volume of air passed through the gas flow measurement device 5 for the time interval t _u is determined by the formula:

, (4)

, (4)

The actual value of the volume (flow) of gas depends on the ratio "temperature - humidity" and on the pressure drop on the calibrated device for measuring gas flow 5. This dependence is taken into account using the coefficients K _tφ and the multiplier (1-ΔP / P _atm ):

(5), где

(5), where

ΔP is the pressure difference between the inlet to critical nozzle 1 and the atmosphere, measured by differential pressure sensor 8, kPa;

P _atm - atmospheric air pressure, measured by atmospheric pressure sensor 11, kPa.

From formulas 3-5, the volume of gas is calculated by the formula:

(6).

(6).

The values of K _tφ are given in the table.

ϕ, % Temperature, °C ten 12 fourteen sixteen eighteen 20 22 24 26 28 thirty thirty 1.002 1.002 1.002 1.001 1.001 1.001 1.001 1.001 1.001 1,000 1,000 40 1.002 1.001 1.001 1.001 1.001 1.001 1.001 1,000 1,000 0.9988 0.9995 fifty 1.001 1.001 1.001 1.001 1.001 1,000 1,000 0.9998 0.9995 0.9992 0.9988 60 1.001 1.001 1.001 1.001 1,000 1,000 0.9998 0.9993 0.9989 0.9984 0.9980 70 1.001 1.001 1,000 1,000 0.9999 0.9996 0.9993 0.9988 0.9983 0.9978 0.9973 80 1.001 1,000 1,000 0.9999 0.9995 0.0092 0.9988 0.9983 0.9978 0.9972 0.9965 90 1.001 1,000 0.9999 0.9996 0.9992 0.9988 0.9983 0.9978 0.9972 0.9965 0.9959

At the end of pumping through the gas flow measurement device 5, the flow rate (volume) is read from it and compared with the calculated values taken as reference ones.

The relative error of the installation is determined when reproducing the volume and a conclusion is made about the suitability (unsuitability) of the device for measuring gas flow 5 for use.

Another new essential feature in the technical solution, which provides an increase in the reliability of the installation and the achievement of the claimed technical result, is that during the operation of the installation for calibrating and verifying gas flow measurement devices, as it gets dirty, the opening of the nozzles 1 decreases and, accordingly, the actual gas flow will change. To control the operability of the installation, the gas flow rate is calculated by an indirect method that does not depend on the flow rates of the critical nozzles 1 according to the formula:

(8),

(eight),

where V _p is the total volume of the receiver 3, l;

t _meas – installation operating time, s;

P _n – initial air pressure in receiver 3, kPa;

Р _c – final air pressure in receiver 3, kPa;

T _n is the initial air temperature in the receiver 3, ^o C;

Tc – final air temperature _in receiver 3, ^o C;

P _atm , T _atm - pressure and temperature of the outside air, respectively;

R _n , P _K is measured by an absolute pressure sensor 6. T _n , T _K is measured by a gas temperature sensor 7. R _atm is measured by an ambient air pressure sensor 11. T _atm is measured by an air temperature sensor 10.

At gas flow rates determined by formula 8, less than the initial value, the installation is stopped and maintenance work is carried out.

Claims (4)

1. Installation for calibration and verification of gas flow measurement devices, containing critical nozzles with shut-off valves, a pump, a receiver and a control module, characterized in that for calibration or verification of the device, the control module is configured to set calibration points for gas flow, for each of of which the critical nozzles included in the formation of the flow rate are defined, the nominal flow rates d _i of which are expressed as a power of two and are represented by an n-bit binary number, while the total flow rate of the device is formed as the sum of the flow rates of the critical nozzles with binary weights

, where a _k is a coefficient with values of 0 or 1, taking into account the participation of the critical nozzle in flow formation, while a _k =0, if the critical nozzle is excluded from the flow formation (disabled) and a _k =1, if the critical nozzle is included in the flow formation , sensors are connected to the controller to measure the temperature and pressure of the test medium in the receiver, the temperature, pressure and humidity of the ambient air to measure the parameters of the test medium pumped through the critical nozzles and the environment to determine the volume of the test medium pumped through the measuring device in the control module gas flow rate and relative installation error. 2. Installation according to claim 1, characterized in that the flow rate of each of the critical nozzles is determined as

, the first of which is selected from a range of 0.004, 0.008, 0.016, 0.032, 0.064 m ³ /hour. 3. Installation according to claim 1, characterized in that the volume of the calibration medium is determined as

, where ΔP is the pressure difference between the inlet to the critical nozzle and the atmosphere, P _atm is the atmospheric air pressure measured by the atmospheric pressure sensor, K is the calibration coefficient of the critical nozzle, K _tφ is the temperature-humidity dependence coefficient. 4. Installation according to claim 1, characterized in that the pressure difference between the critical nozzle inlet and the atmosphere is measured by a differential pressure sensor connected downstream of the gas flow measurement device.

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