RU2624593C1 - Installation for verifying hot water meters - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: hot water meter verifying system contains a test section of the pipeline, in which the reference and verified water meters and a flow controller, a computing device, a water heater, temperature sensors and a shut-off valve are installed in series. Water heater is placed on the test section of the pipeline between the reference and verified water metersand designed as a steam heat exchanger provided with a control temperature of hot water passing through the calibratable meter containing hot water temperature sensor disposed in the test section of the pipe immediately behind the varified meter, and connected to the hot water temperature sensor control unit, the output of which is connected to the valve actuator installed in the steam line of the steam heat exchanger. Herewith a cold water temperature sensor is installed directly behind the reference meter on the pipeline test section. The outputs of the reference and verified water meters, as well as cold and hot water temperature sensors are connected to the inputs of the computing device. The input of the pipeline test section is connected through the valve to the cold water pressure line, and its output is connected through the gate valve to the return collector of the heat source network water.

EFFECT: increasing the accuracy of measuring the actual values of the volume of hot water passing through the verified meters in the temperature range corresponding to the operating conditions of the verified meters of the water heating systems, the upper limit of which is 200 degrees.

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Description

The invention relates to measuring equipment and can be used to verify hot water meters, mainly in heat supply systems.

A known installation for verification of hot water meters (vane, turbine, induction, ultrasonic, vortex, etc.) volumetric type (Recommendation. State system for ensuring the uniformity of measurements. Water meters. Verification method MI1592-99) - [1]. The installation consists of a measuring part, including means for measuring the volume of water, made in the form of a measuring tank, a system for setting calibration costs, a test section for installing a verified meter, as well as a system for refueling, storage and stabilization of water flow. The water temperature during calibration of the meters does not exceed 40 ° C.

The known installation of the EP-50 volumetric type with a reference capacity for checking water meters (Gudkin MB, Mishustin V.I., Chistyakov Yu.A. Metrological support for measuring the flow and volume of liquids and gases in Russia // Measuring equipment, 2010. - No. 3. - S. 30-34) - [2]. The EP-50 installation, the relative error of which is 0.1% in the temperature range of the medium to be measured is 15-90 ° C, is one of the most accurate, providing calibration of reference meters with the highest working temperature of the coolant up to 90 ° C.

A mass calibration installation for hot water meters is also known, the measuring part of which includes a tank mounted on the weighing platform connected to a test section with a flexible hose (Recommendation. State system for ensuring the uniformity of measurements. Apartment cold and hot water meters. Periodic calibration procedure during operation of MI 2997- 2006) - [3]. The temperature of the medium measured - hot water is 40-60 ° C.

A common drawback of these installations is the significant difference between the verification conditions carried out at an insufficiently high temperature of the measured medium - not more than 90 ° C, from the actual operating conditions of the meters in water heating systems at a coolant temperature of up to 200 ° C (SP 124.13330.2012 Heating networks. Updated version SN and P41-02-2003) - [4] and (GOST R 51649-2000 Heat meters for water heat supply systems. General specifications) - [5], which reduces the accuracy of verification and can lead to an increase in the measurement error of the volume of carrier compared to the error regulated (MI 2538-99 "GSI. Heat meters for water heating systems. General metrological requirements") - [6], which is 1%.

At the same time, an increase in the temperature and pressure of the measured medium in these types of installations in order to ensure that the conditions for checking hot water meters are compatible with the conditions of their operation [4, 5] is limited by a decrease in the accuracy of the calibration installations.

For volumetric calibration installations, this is due to the appearance of an additional error from a change in the capacity of the measuring tank due to its deformation under the influence of temperature and pressure, as well as an error in the measurement of volume due to mass transfer at the gas-liquid interface.

In mass calibration plants, a change in temperature and pressure of the medium being measured leads to a change in the stiffness of the flexible connection of the tank installed on the weighing platform with the test section, which leads to a decrease in the weighing accuracy.

The closest analogue to the claimed device is a installation for checking hot water meters, containing a test section of the pipeline with a reference and calibrated meters and a flow controller installed in series with it, a computing device, a water heater, temperature sensors and shutoff valves (RF Patent No. 2234689, M. C. G01F 25/00) - [7].

The principle of operation of the known installation is based on the circulation of hot water using a pump in a closed circuit, including a drive and a test section of the pipeline on which the reference and verified meters are installed in series with the flow and verification by comparing their indicators at a single temperature of the water flowing through them.

To heat water in the reservoir, a separate closed loop is used, consisting of a pump that draws water from the reservoir and supplies it through the heater back to the reservoir.

A disadvantage of the known installation is the low accuracy at high temperatures of the measured medium due to a significant additional temperature error of the main element of the comparison device - the reference counter.

As reference counters in a known comparison system, as a rule, turbine and electromagnetic meters are used, which are characterized by high accuracy and stability of the conversion coefficient. The error of the indicated counters δ ₀ during their calibration and verification, for example, using the installation of the volumetric type EP-50 [2], does not exceed 0.3% in the temperature range of the medium to be measured 15 ... 90 ° C.

However, when the temperature of hot water in the known comparison plant rises above the upper limit of the temperature range of 90 ° C, at which calibration and calibration of the reference counters was carried out, their accuracy decreases due to the appearance of an additional temperature error δ _t .

For a turbine meter, an approximate estimate of the error δt according to (Tseytlin VG Flow metering equipment. M., Iz-in standards, 1977. - 240 p.) - [8] is calculated by the formula

where β is the coefficient of linear thermal expansion of the material of the rotor and the case of the turbine meter, for stainless steel β = 17.3⋅10 ^-6 (° C) ^-1 , t _max is the maximum temperature of the medium in a known comparison plant, in accordance with the requirements regulatory documents [4, 5] operation of hot water meters in the heat supply system can be carried out at temperatures up to 200 ° C, therefore, verification of these meters must be carried out at t _max = 200 ° C; t ₂ - the upper limit of the temperature range at which in the above example the calibration and calibration of the reference counter were carried out, t ₂ = 90 ° C.

After substituting the numerical values of the parameters in (1), we obtain that the additional temperature error of the reference turbine meter when used in the known installation δ _t will be 0.57%.

The value of the total error of this counter δ _Σ is determined from the expression

Therefore, in the known comparison system at the given temperature conditions, the error of the reference turbine meter δ _Σ = 0.87% becomes comparable with the error of the verified hot water meter, which according to [6] should not exceed 1%, which does not allow to obtain reliable verification results.

The additional temperature error of the electromagnetic counter is primarily due to a change in the nature of the distribution of the magnetic field in the channel of the counter depending on the change in temperature of the medium being measured. In (GOST 11988-81. Flowmeters and measuring transducers of electromagnetic electromagnetic flow) - [9] a methodology was given for determining the limits of permissible changes in the error of devices caused by changes in the temperature of the measured medium within the operating temperature range for every 10 ° C for a stationary liquid. For example, for the IR-51 device, the value of this additional temperature error is 0.3 of its basic error at a temperature of the medium being measured 20 ± 5 ° C.

The results of spillages of a number of industrial electromagnetic meters on hot-water stands with a temperature range of the working medium of 23-73 ° C showed that their relative error significantly depends on both the flow rate and the temperature of the working medium. For example, for one of the sample meters at a given flow rate of the working medium of 15 m ³ / h with an increase in its temperature from 33 to 43 ° C, the relative error of the meter changed from 0.81 to - 0.42%, i.e. by 1.2%. (Kavrigin SB, Prilutsky AV Analysis of operating experience of electromagnetic flowmeters in metering systems. Commercial metering of heat carriers. Materials of the XI International scientific and practical conference, 2000. - SPb. - S. 114-117) - [10].

Thus, the use of a well-known calibration installation with reference meters at a temperature of the medium measured above the upper limit of the temperature range at which they were calibrated and verified, significantly reduces its accuracy and does not allow calibration of hot water meters at temperatures corresponding to the actual energy temperatures in the systems heat supply.

The objective of the invention is to increase the accuracy of the installation for calibration of hot water meters. The problem posed by the present invention is solved by the fact that in a known installation for checking hot water meters, comprising a test section of a pipeline on which reference and verified water meters and a flow controller, a computing device, a water heater, temperature sensors and shutoff valves, are installed in series with the flow water is placed on the test section of the pipeline between the reference and verifiable water meters and is made in the form of a steam heat exchanger equipped with a regulator a hot water temperature passing through a verified meter containing a hot water temperature sensor located on the test section of the pipeline directly behind the verified meter, and a control unit connected to the hot water temperature sensor, the output of which is connected to a valve actuator installed in the steam supply line to the steam a heat exchanger, while on the test section of the pipeline directly behind the reference meter, a cold water temperature sensor is installed, the outputs of the reference and verified water meters, and temperature sensors hot and cold water are connected to inputs of a computing device, the test section through the inlet valve is connected with the pressure line of cold water, and its output is connected through a shut-off valve to the return collector of the power of the heat source water.

Distinctive features according to the invention is that the water heater is located on the test section of the pipeline between the reference and verifiable water meters and is made in the form of a steam heat exchanger equipped with a temperature controller for hot water passing through a verifiable counter containing a hot water temperature sensor located on the test section of the pipeline immediately after the meter being verified, and the control unit connected to the hot water temperature sensor, the output of which is connected to with a valve actuator installed in the steam supply line to the steam heat exchanger, while on the test section of the pipeline directly behind the reference meter a cold water temperature sensor is installed, the outputs of the reference and verified water meters, as well as cold and hot water temperature sensors are connected to the inputs of the computing device, input the test section through the valve is connected to the cold water pressure line, and its output through the gate valve is connected to the return manifold of the network water source but heat.

Placing a water heater, made in the form of a steam heat exchanger, in the test section between the reference and verified water meters sequentially installed on it in a stream, allowed a water stream to pass through them having different temperature values when it passed through the reference and verified meters. When water flows through the reference meter, its temperature has a normal value of 20 ± 5 ° C, therefore, under the indicated application conditions, the reference meter has higher accuracy and its main error can be in the range 0.15-0.2%.

At the same time, when water flows through the verified meter due to the heater, it is heated to a temperature corresponding to the actual temperature of its operation in heating networks, which, according to regulatory documents [4, 5], can reach 200 ° C.

The result is an increase in the accuracy of the proposed installation, in which verification is carried out by comparing the readings of the reference counter, reduced to the temperature of the measured medium passing through the verified counter, with its readings.

The connection of the inlet of the test section through the valve with the pressure line of cold water and the connection of its output through the gate valve to the return manifold of the network water of the heat source eliminates unnecessary consumption of hot water during verification.

In FIG. 1 shows a setup diagram for checking hot water meters.

The installation comprises a test section of the pipeline 1, on which a reference counter of cold water 2 is installed sequentially downstream, immediately after it is a cold water temperature sensor 3, a steam heat exchanger 4, a verified hot water meter 5, immediately after it is a hot water temperature sensor 6, and flow regulator 7.

As a reference cold water meter 2, turbine meters, for example, Smith with a basic error of δ _from no more than 0.15% or electromagnetic meters, for example, ADMAG AXF, whose basic error of δ _oe does not exceed 0, can be used in the installation , 2%.

The steam heat exchanger 4 is equipped with a temperature controller 8 for hot water passing through a verifiable meter 5 containing a hot water temperature sensor 6 connected to the input of the control unit 9, the output of which is connected to the actuator 10, of the valve 11 installed in the steam supply line 12 to the steam heat exchanger 4 .

The setup includes a computing device 13, the inputs of which are connected to the outputs of the reference 2 and verified 5 counters, as well as temperature sensors for cold 3 and hot 6 water.

The input of the test section 1 through the valve 14 is connected to the pressure line of cold water, and its output through the shutoff valve 15 is connected to the return manifold of the network water of the heat source.

Installation for checking hot water meters works as follows. With the valve 14 and the gate valve 15 fully open, the cold water stream from the pressure line is fed into the test section of the pipeline 1, passes through the reference cold water counter 2 and enters the steam heat exchanger 4, where the water is heated to the set temperature, then the hot water stream passes a water meter 5, a flow controller 7, which provides the installation of a given flow rate, a shutoff valve 15 and is supplied to the return collector of the network water of the heat source.

With the help of the hot water temperature controller 8, hot water passing through the verified meter 5 is heated to a predetermined temperature level and stabilized at this level in its operating ranges of flow and temperature, the latter can be 20-200 ° C.

When the controller 8 is operating, the signal from the hot water temperature sensor 6 is fed to the input of the control unit 9, where it is compared with a signal proportional to the set level of the hot water temperature, and after amplification and conversion, the error signal from the output of the control unit 9 enters the actuator 10 of the valve 11, which regulates the supply of steam through line 12 to the steam heat exchanger 4 in such a way as to stabilize the temperature of heating of hot water passing through the verified meter 5 at a predetermined level.

After setting the calibration flow in the test section of the pipeline 1, using the flow controller 7, and heating the hot water to a predetermined temperature level, the hot water meter 5 is checked. At the same time, the inputs of the reference 2 and the calibrated 5 meters are sent to the inputs of the computing device 13, and also the signals from the sensors of the temperature of cold water 3 and hot water 6, respectively proportional to the temperature of cold water t _e passing through the reference counter 2, and the temperature of hot water t _p passing through p counter 5.

In the computing device 13 for a certain time interval, the volumes of water V _e measured by the reference meter 2 and V _p measured by the verified meter 5, respectively, are calculated at a temperature t _e and t _p .

Also, the computing device 13 determines the value of the volume of water V _t measured by the reference counter 2, reduced to the temperature of hot water t _p

where α is the coefficient of volumetric thermal expansion of water, t _p = t _p -t _e is the temperature difference of the water passing through the calibrated and reference meters.

The relative error of the verified hot water meter 5 is determined by the computing device 13 according to the formula

Calibration of the hot water meter 5 is carried out in its operating ranges of flow and temperature.

Define the error estimate of the proposed installation for calibration of hot water meters.

During verification, the value of the volume V _t measured by the reference meter 2 at a temperature t _e and reduced to the temperature of hot water t _p is the actual value of the volume of hot water passing through the verified meter 5 with which its readings are compared, therefore, the error in determining the volume V _t can serve as an estimate of the error of the calibration setup.

и

, характеризующие веса с которыми в суммарную абсолютную погрешность ΔV_t входят составляющие погрешности измерения объема V_э и разницы температуры t_p, соответственно ΔV_э и Δt_p. Таким образом суммарная абсолютная погрешность ΔV_t составляетTo estimate the error in determining the volume V _t , the value of which is obtained from equation (3), we calculate the partial derivatives of the volume V _t with _respect to the parameters V _e and t _p - respectively

and

, characterizing the weights with which the total absolute error ΔV _t includes the components of the measurement error of the volume V _e and the temperature difference t _p , respectively, ΔV _e and Δt _p . Thus, the total absolute error ΔV _t is

After calculating the partial derivatives, we have

в процентах, обе части уравнения (6) разделим на значение объема V_э и умножим на 100, с учетом того, что

, относительная погрешность измерения объема V_t составитTo obtain the relative value of the error

in percent, both parts of equation (6) are divided by the value of the volume V _e and multiplied by 100, given the fact that

, the relative measurement error of the volume V _t will be

where δ _о is the basic error of the reference meter, determined at a temperature of 20 ± 5 ° C, while for used as a reference turbine meter, δ _of is 0.15%, and for the electromagnetic meter, δ _Ое is 0.2%;

t _p = t _p -t _e - the temperature difference of the water passing through the calibrated and the reference meter, in accordance with the requirements of regulatory documents [4, 5] the temperature t _p can reach 200 ° C, the temperature t _e according to the conditions of use of the reference meter is 20 ° C, thus t _p = 180 ° C;

Δt _{p the} error of measuring the temperature difference t _p -t _e for temperature sensors used in heat meters according to [6], the error Δt _p when the temperature difference t _p equal to 180 ° C does not exceed 1 ° C;

α is the coefficient of volumetric thermal expansion of water, α = 300⋅10 ^-6 (° C) ^-1

определения объема V_t, а следовательно, и погрешность предложенной установки при использовании в качестве эталонного счетчика соответственно турбинного счетчика с погрешностью δ_от, равной 0,15%, и электромагнитного счетчика с погрешностью δ_оэ, составляющей 0,2%We calculate by the formula (7) the error

determining the volume V _t , and consequently, the error of the proposed installation when using a turbine meter with an error δ _of 0.15% and an electromagnetic meter with an error δ _{oe of} 0.2% as a reference meter, respectively

Thus, the error of the proposed installation for checking hot water meters when using turbine or electromagnetic meters as a reference meter according to (8) and (9) will be 0.19 or 0.24%, respectively, in the range of the temperature of the measured medium of 20-200 ° C .

The use of the proposed installation, with an error of less than 0.19 or 0.24%, can significantly improve the accuracy of measuring the actual values of the volumes of hot water passing through the verified meters in the temperature range corresponding to the operating conditions of the verified meters for water heating systems, the upper limit of which is 200 ° C [4, 5].

The development and operation of the proposed installation for checking hot water meters is planned at Kazan TPP-1, while the efficiency and low cost of its operation at the TPP are due to the following factors:

1. The possibility of using in the heat exchanger a calibration unit produced at the CHPP of selected steam, with a pressure of 1.3 MPa and a temperature of 300 ° C, for heating the flow of water flowing through the calibrated hot water meter.

2. The exclusion of unproductive losses of hot water during verification due to the fact that the water heated when passing through the unit to a predetermined temperature enters the return manifold of the CHP network water for subsequent use in the heat supply system.

Literature

1. Recommendation. State system for ensuring the uniformity of measurements. Water meters. Calibration Method MI 1592-99.

2. Gudkin M.B., Mishustin V.I., Chistyakov Yu.A. Metrological support for measuring the flow rate and volume of liquids and gases in Russia // Measuring equipment, 2010. - No. 3. - S. 30-34.

3. Recommendation. State system for ensuring the uniformity of measurements. Housing meters for cold and hot water. The method of periodic verification during the operation of MI 2997-2006.

4. SP 124.13330.2012 Heating networks. Updated version of SN and P41-02-2003.

5. GOST R 51649-2000 Heat meters for water heat supply systems. General specifications.

6. MI 2538-99 “GSI. Heat meters for water heat supply systems. General metrological requirements. "

7. RF patent No. 2234689, M. cl. G01F 25/00.

8. Zeitlin V.G. Flow measuring equipment. M., Publishing house of standards, 1977. - 240 p.

9. GOST 11988-81. Flowmeters and measuring transducers, electromagnetic, industrial.

10. Kavrigin S.B., Prilutsky A.V. Analysis of operating experience of electromagnetic flowmeters in metering systems. Commercial metering of coolants. Materials of the XI International scientific-practical conference, 2000. - SPb. - S. 114-117.

Claims (1)

Installation for checking hot water meters, containing a test section of the pipeline, on which the reference and verifiable water meters and a flow controller, a computing device, a water heater, temperature sensors and shut-off valves are installed in series with the flow, characterized in that the water heater is located on the test section of the pipeline between the reference and verifiable water meters and is made in the form of a steam heat exchanger equipped with a temperature controller for hot water passing through the a removable meter containing a hot water temperature sensor located on the test section of the pipeline directly behind the meter to be verified, and a control unit connected to the hot water temperature sensor, the output of which is connected to a valve actuator installed in the steam supply line to the steam heat exchanger, while on the test section The pipe directly behind the reference meter has a cold water temperature sensor, the outputs of the reference and verified water meters, as well as cold temperature sensors and hot water are connected to inputs of a computing device, the test section inlet pipe through a valve connected to the pressure line of cold water, and its output is connected through a shut-off valve to the return collector of the power of the heat source water.

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