CN110926570B - Method and apparatus for calibrating a critical flow venturi nozzle - Google Patents
Method and apparatus for calibrating a critical flow venturi nozzle Download PDFInfo
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- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
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Abstract
The invention discloses a method and a device for calibrating a critical flow venturi nozzle, and belongs to the field of natural gas metering application. The method comprises the following steps: acquiring the total initial measurement time of a total error test, the initial measurement time of a fractional error test and the test times of the fractional error test, and determining the error time; acquiring initial measurement time of a critical flow Venturi nozzle to be calibrated, and measuring the mass of gas flowing through the critical flow Venturi nozzle to be calibrated in the initial measurement time; calculating a difference value obtained by subtracting the error time length from the initial test time length to obtain a real measurement time length; and calibrating the critical flow venturi nozzle to be calibrated according to the real measuring time length and the measured gas mass. By adopting the method and the device, the result of calibrating the critical flow Venturi nozzle can be more accurate.
Description
Technical Field
The invention relates to the field of natural gas metering application, in particular to a method and a device for calibrating a critical flow venturi nozzle.
Background
In order to solve the real-flow verification problem of the high-pressure and large-caliber natural gas flow meter, the national measurement administrative department authorizes Chinese petroleum to build a Nanjing substation of a national petroleum and natural gas large-flow measurement station, and mt (quality-time) method high-pressure natural gas flow standard equipment is the source of a Nanjing substation natural gas flow quantity value transmission system, is used for reproducing the mass flow value of high-pressure natural gas and calibrating a critical flow Venturi nozzle in a secondary standard, and is the first set of high-pressure natural gas flow primary standard equipment in China.
The timing system of the standard equipment measures the test duration by using Agilent 5313A type frequency counter measuring equipment, and the uncertainty of the measurement is 1 multiplied by 10-4s, representing a degree of uncertainty of the measurement relative to the measurement itself, is 0.01%, k is 2, representing a degree of confidence of about 95%. The triggering of the timer is controlled by the rotating angles of the two quick reversing valves, and the testing time length of a single test is the time length from the closing of the quick reversing valve XV9005 to the closing of the quick reversing valve XV 9003.
However, when the rapid reversing valve is switched, due to different pressure differences, the switch stroke duration is also different, so that an error duration exists in the measured test duration, the error duration causes the test duration to be inaccurate, and further, the result of calibrating the critical flow venturi nozzle is inaccurate.
Disclosure of Invention
To solve the problems of the prior art, embodiments of the present invention provide a method and apparatus for calibrating a critical flow venturi nozzle. The technical scheme is as follows:
in a first aspect, there is provided a method of calibrating a critical flow venturi nozzle, the method comprising:
acquiring total initial measurement time of a total error test, initial measurement time of a fractional error test and test times of the fractional error test;
determining error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test and the test times of the fractional error test;
acquiring initial measurement time of a critical flow Venturi nozzle to be calibrated, and measuring the mass of gas flowing through the critical flow Venturi nozzle to be calibrated in the initial measurement time; the initial measurement duration is a timing duration obtained from starting timing to stopping timing in the process that gas flows through the critical flow venturi nozzle to be calibrated;
calculating a difference value obtained by subtracting the error time length from the initial test time length to obtain a real measurement time length;
and calibrating the critical flow venturi nozzle to be calibrated according to the real measuring time length and the measured gas mass.
Optionally, the obtaining of the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, and the test times of the fractional error test includes:
acquiring total initial measurement time of a total error test, initial measurement time of a fractional error test, test times of the fractional error test and a measurement parameter ratio of the total error test to the fractional error test;
the determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test and the test times of the fractional error test comprises the following steps:
and determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test and the measurement parameter ratio of the total error test to the fractional error test.
Optionally, the obtaining of the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test, and the ratio of the measurement parameters of the total error test and the fractional error test includes:
acquiring the total initial measurement time length of a total error test, the gas mass and the gas molar mass in the total error test, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle;
acquiring the initial measurement duration of a fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test;
and determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
Optionally, the determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the number of times of the fractional error test, and the ratio of the total error test to the measurement parameter of the fractional error test includes:
according to the following formula, the error duration is calculated,
wherein, Deltat is the error duration, B is the ratio of the measurement parameters, t' is the initial measurement duration of the fractional error test, t1And n is the test times of the fractional error tests.
Optionally, the acquiring an initial measurement duration of the critical flow venturi nozzle to be calibrated and measuring a mass of gas flowing through the critical flow venturi nozzle to be calibrated in the initial measurement duration includes:
when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment;
when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment;
when the second reversing valve is closed to the preset angle, timing is stopped;
determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length;
determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
In a second aspect, there is provided an apparatus for calibrating a critical flow venturi nozzle, the apparatus comprising:
the acquisition module is used for acquiring the total initial measurement time of a total error test, the initial measurement time of a fractional error test and the test times of the fractional error test;
the determining module is used for determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test and the test times of the fractional error test;
the measuring module is used for acquiring the initial measuring time length of the critical flow Venturi nozzle to be calibrated and measuring the mass of gas flowing through the critical flow Venturi nozzle to be calibrated in the initial measuring time length; the initial measurement duration is a timing duration obtained from starting timing to stopping timing in the process that gas flows through the critical flow venturi nozzle to be calibrated;
the calculation module is used for calculating a difference value obtained by subtracting the error time length from the initial test time length to obtain a real measurement time length;
and the calibration module is used for calibrating the critical flow venturi nozzle to be calibrated according to the real measurement time length and the measured gas quality.
Optionally, the obtaining module is further configured to:
acquiring total initial measurement time of a total error test, initial measurement time of a fractional error test, test times of the fractional error test and a measurement parameter ratio of the total error test to the fractional error test;
the determining module is further configured to:
and determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test and the measurement parameter ratio of the total error test to the fractional error test.
Optionally, the obtaining module is further configured to:
acquiring the total initial measurement time length of a total error test, the gas mass and the gas molar mass in the total error test, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle;
acquiring the initial measurement duration of a fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test;
and determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
Optionally, the determining module is further configured to:
according to the following formula, the error duration is calculated,
wherein, Deltat is the error duration, B is the ratio of the measurement parameters, t' is the initial measurement duration of the fractional error test, t1And n is the test times of the fractional error tests.
Optionally, the measurement module is configured to:
when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment;
when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment;
when the second reversing valve is closed to the preset angle, timing is stopped;
determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length;
determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
In a third aspect, a terminal is provided, the terminal comprising a processor and a memory, the memory having stored therein at least one instruction, the at least one instruction being loaded and executed by the processor to implement the method for calibrating a critical flow venturi nozzle as described in the first aspect above.
In a fourth aspect, there is provided a computer readable storage medium having stored therein at least one instruction that is loaded and executed by the processor to implement the method of calibrating a critical flow venturi nozzle as described above in the first aspect.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
in the embodiment of the invention, the error time length is obtained by calculating through an error test, when the critical flow venturi nozzle to be calibrated is calibrated, the real measurement time length is calculated according to the obtained initial measurement time length and the error time length, and then the critical flow venturi nozzle to be calibrated is calibrated according to the real measurement time length and the measured gas mass. Therefore, the initial measurement time length is corrected through the error time length, the obtained real measurement time length is more accurate, and further, the result of calibrating the critical flow venturi nozzle can be more accurate.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a system flow diagram of a method of calibrating a critical flow venturi nozzle provided by an embodiment of the present invention;
FIG. 2 is a flow chart of a method of calibrating a critical flow venturi nozzle provided by an embodiment of the present invention;
FIG. 3 is a flow chart of the operation of a method of calibrating a critical flow venturi nozzle provided by an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a device for calibrating a critical flow venturi nozzle provided by an embodiment of the invention;
fig. 5 is a schematic structural diagram of a terminal according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The invention provides a method for calibrating a critical flow venturi nozzle, which is applied to a calibration system, as shown in fig. 1, the calibration system at least comprises a first reversing valve, a second reversing valve, a critical flow venturi nozzle to be calibrated, a mass measurement device for measuring the mass of gas, and in addition, a gas pressure measurement device, a temperature measurement device, a gas circulation pipeline and the like, which can be used for measuring other measurement parameters, for example, the gas pressure measurement device can be used for measuring the parameter of gas pressure, and the temperature measurement device is used for measuring the parameter of temperature. As shown in fig. 2, the processing flow of the method may include the following steps:
in step 201, a total initial measurement time of the total error test, an initial measurement time of the fractional error test, and a test number of the fractional error test are obtained.
In one possible embodiment, in order to calibrate the critical flow venturi nozzle, a technician may perform a plurality of error tests before performing the calibration test, wherein the plurality of error tests may be divided into a one-time total error test and a plurality of time-division error tests, and record a total initial measurement duration of the total error test, an initial measurement duration of the time-division error test, and a test time of the time-division error test. The error test uses the same equipment as the calibration test (i.e., the calibration system) which may include at least two directional valves, critical flow venturi nozzles to be calibrated, gas mass measurement devices, gas pressure measurement devices, temperature measurement devices, gas flow conduits, etc., as shown in fig. 2.
Optionally, when the multiple error tests are performed, not only the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, and the test times of the fractional error test need to be determined, but also the measurement parameter ratio of the total error test to the fractional error test needs to be determined, so that the processing steps of obtaining the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test, and the measurement parameter ratio of the total error test to the fractional error test may be as follows:
the total initial measurement duration of the total error test, the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow venturi nozzle, the critical flow function under stagnation conditions, and the stagnation pressure at the upstream inlet of the critical flow venturi nozzle in the total error test are obtained.
The method comprises the steps of obtaining the initial measurement duration of the fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
And determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
In one possible embodiment, the error test is performed by first setting a total initial measurement time t1The total initial measurement duration is used to perform a total error test. Then, the first initial measurement time period is equally divided into n parts, and the initial measurement time period of each part is t ', wherein t' is t ═ t1And the/n and the t' are used for carrying out fractional error tests, and the times of the fractional error tests are n times.
Then, the initial measurement time length is taken as the total initial measurement time length t1An error test (which may be referred to as a gross error test) is performed and various measured parameters are recorded, including gas mass, stagnation temperature at the upstream inlet of the critical flow venturi nozzle, stagnation pressure at the upstream inlet of the critical flow venturi nozzle, and the like. And then, continuously carrying out n times of fractional error tests according to the initial measurement time as t', recording various measurement parameters in each fractional error test, and finally calculating the sum of the gas quality, the average value of stagnation temperature and the average value of stagnation pressure in the fractional error tests.
Then, the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow venturi nozzle, the critical flow function under stagnation conditions, the stagnation pressure at the upstream inlet of the critical flow venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow venturi nozzle, the critical flow function under stagnation conditions, the stagnation pressure at the upstream inlet of the critical flow venturi nozzle in the fractional error test are calculated, and the ratio of the measurement parameters of the total error test and the fractional error test is calculated according to the following formula (1).
Wherein M represents the gas mass in the total error test, M 'represents the gas mass in each fractional error test, M represents the gas molar mass in the total error test, M' represents the gas molar mass in each fractional error test, T represents the total errorThe stagnation temperature at the upstream inlet of the critical flow venturi nozzle in the test, T' represents the stagnation temperature at the upstream inlet of the critical flow venturi nozzle in each fractional error test, C*Represents the critical flow function under stagnation conditions in the gross error test, C*'represents the critical flow function under stagnation conditions in each fractional error test, p represents the stagnation pressure at the upstream inlet of the critical flow venturi nozzle in the total error test, and p' represents the stagnation pressure at the upstream inlet of the critical flow venturi nozzle in each fractional error test.
It should be noted that, in addition to the above manner, the method for obtaining the initial measurement duration of the multiple error tests may further include the following steps.
And (3) carrying out multiple times of fractional error tests by using equipment of the calibration system, respectively recording the initial measurement time of each time of fractional error test, each measurement parameter in each time of fractional error test and the times of the fractional error test, and calculating the average value of each measurement parameter of the multiple times of error tests and the sum value (namely the total initial measurement time) of the initial measurement time of the fractional error test. And then carrying out an error test (namely a total error test) according to the total initial measurement time length, and recording various measurement parameters of the total error test. There are many methods for obtaining the total initial measurement parameter of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test, and the ratio of the measurement parameters of the total error test and the fractional error test, and the present invention is not limited to this.
In step 202, an error duration is determined according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, and the test times of the fractional error test.
Alternatively, the error duration may be determined according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test, and the measurement parameter ratio of the total error test to the fractional error test.
In one possible embodiment, t is determined according to the above steps1N, t' and the measured parameter ratio are calculatedTo the error duration.
Optionally, according to t in the above step1N, t' and the ratio of the measurement parameters, and calculating the error duration according to the following formula;
wherein, delta t is error duration, B is a ratio of measurement parameters, t' is the measurement duration of each time in n times of fractional error tests, t1The total initial measurement time of the total error test is shown, and n is the times of the fractional error test.
It should be noted that the above formula for calculating the error duration may be derived based on the following idea:
firstly, a calculation formula of the outflow coefficient of the critical flow Venturi nozzle is determined:
wherein, Cd'Representing the critical flow venturi nozzle outflow coefficient; q. q.smThe instantaneous mass flow is expressed in kg/h; r represents a general gas constant in the unit of J (mol. K)-1(ii) a M represents the molar mass of the gas in kg. mol-1；T0Represents the stagnation temperature at the upstream inlet of the critical flow venturi nozzle in K; a represents the critical flow Venturi nozzle throat section area in m2；C*Representing the critical flow function under stagnation conditions; p is a radical of0Representing the stagnation pressure in Pa at the upstream inlet of the critical flow venturi nozzle.
Based on instantaneous mass flow qmDefinition of (1): q. q.smThe above formula (3) can be converted into the following formula (4):
wherein m represents the mass of gas in kg; t represents the real measurement duration in h.
Further, the air conditioner is provided with a fan,
assuming that the error duration is Δ t, the initial measurement duration in one test (i.e. the total initial measurement duration corresponding to the total error test) is t1Then, according to the above formula (5), it can obtain:
based on the above idea, when n times of tests (i.e. n times of fractional error tests) are continuously performed, and the initial measurement duration of each test (the initial measurement duration of the fractional error test) is t', the corresponding formula is:
wherein m' represents the gas mass measured in kg in each test when n times of fractional error tests are carried out; c'd' represents the critical flow venturi nozzle outflow coefficient when n times of fractional error tests are carried out; m' represents the molar mass of the gas in kg. mol per test when n fractional error tests were performed-1(ii) a T' represents the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle of each test when n times of error tests are carried out, and the unit is K; a' represents the critical flow Venturi nozzle throat section area of each test when n times of fractional error tests are carried out, and the unit is m2；C*' represents the critical flow function for stagnation conditions measured for each trial when n fractional error trials are performed; p' represents the stagnation pressure in Pa at the upstream inlet of the critical flow venturi nozzle measured for each trial when n fractional error trials were conducted.
Dividing the above formula (6) by the above formula (7):
because the same calibration system is adopted for calibration, the sectional area of the throat part of the critical flow venturi nozzle is the same no matter how many times of tests are carried out, and the outflow coefficients are the same, the formula can be converted into the following formula:
suppose that
The above formula (9) can be converted into:
finally, an expression formula of Δ t can be derived from formula (10):
wherein the content of the first and second substances,
in order to verify the correctness of the derivation formula, the derivation formula can be verified through experiments, and the uncertainty of the error duration is calculated. In calculating the uncertainty of the error duration, the standard deviation of the error duration may be calculated by a bezier equation, as shown in the following equation (12):
after the standard deviation is found, 1/2 of the standard deviation is the relative standard uncertainty of the error duration.
In step 203, an initial measurement time period of the critical flow venturi nozzle to be calibrated is obtained, and the mass of the gas flowing through the critical flow venturi nozzle to be calibrated in the initial measurement time period is measured.
And the initial measurement time length is a timing time length obtained from the start of timing to the stop of timing in the process of gas flowing through the critical flow venturi nozzle to be calibrated.
In one possible embodiment, when the technician wants to calibrate the critical flow venturi nozzle (i.e., the critical flow venturi nozzle to be calibrated), it is first determined whether the connections between the devices in the calibration system are correct, which is the same set of equipment as the calibration system used in the error test described above.
When the calibration test is started, the gas is controlled to flow through the critical flow venturi nozzle to be calibrated, the time length (namely the initial measurement time length) of the gas flowing through the critical flow venturi nozzle to be calibrated is recorded at the terminal, and the mass of the gas flowing through the critical flow venturi nozzle to be calibrated is measured through the mass measurement equipment. The mass measuring device can be a weighing spherical tank, and after the measurement is started, the gas flows into the weighing spherical tank after flowing through the critical flow venturi nozzle to be calibrated, and the weighing spherical tank measures the gas mass of the flowing gas.
It should be noted that, in a calibration test, the initial measurement duration may be preset, and after the timing is started, the timing is stopped after the timing duration reaches the preset initial measurement duration, as long as the initial measurement duration can be obtained, which is not limited in the present invention.
Alternatively, the terminal may control the linkage among the plurality of reversing valves so that the gas flows into the gas quality detection device, and the initial measurement time length of the gas flowing through the critical flow venturi nozzle to be calibrated is determined in a timing manner, and the processing steps of obtaining the initial measurement time length may be as follows: when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment; when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment; when the second reversing valve is closed to the preset angle, timing is stopped; determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length; determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
In one possible embodiment, after the calibration device is turned on, as shown in fig. 2, the gas flows through the critical flow venturi nozzle to be detected, and then, as shown in fig. 3, a closing instruction is sent to the first reversing valve to start closing the first reversing valve, when the first reversing valve is closed by a preset angle, the terminal starts timing by the timer, and sends an opening instruction to the second reversing valve to start opening the second reversing valve, so that the gas flows into the gas quality detection device through the second reversing valve. When the timing duration of the timer reaches the preset duration, the terminal sends a closing instruction to the second reversing valve to stop gas from flowing into the gas quality detection device, and when the second reversing valve is closed to the preset angle, the terminal controls the timer to stop timing and starts the first reversing valve.
Determining the timing duration through a timer, determining the duration from the beginning of timing to the end of timing as an initial measurement duration, and then determining the mass of the gas flowing into the gas mass detection equipment, namely the mass of the gas flowing through the critical flow venturi nozzle to be calibrated in the initial measurement duration.
It should be noted that the preset angle is determined based on the structural characteristics of the directional valve, and when the valve flap in the directional valve is closed to the preset angle, the directional valve can be considered to be completely closed. Preferably, the preset angle may be 78 °, in which case the full open angle of the diverter valve is 0 °.
It should be noted that, during the test, besides detecting the gas quality and the initial measurement duration, the stagnation temperature at the upstream inlet of the critical flow venturi nozzle may be measured by a temperature measuring device, the stagnation pressure at the upstream inlet of the critical flow venturi nozzle may be measured by a gas pressure measuring device, the throat section area of the critical flow venturi nozzle is calculated, and the like.
In step 204, a difference between the initial measurement duration and a pre-stored error duration is calculated to obtain a real measurement duration.
The error duration is error duration generated by different consumed durations when the first reversing valve and the second reversing valve are opened or closed due to different pressure differences of the first reversing valve and the second reversing valve caused by the change of the gas flow.
In one possible embodiment, the terminal obtains the error time length measured in advance and stored for the set of device, and calculates the difference between the initial measurement time length and the error time length measured in the above steps, and the obtained difference is the real measurement time length. Therefore, after the initial measurement time length is corrected through the error time length, the obtained real measurement time length is the time length corresponding to the measured gas quality, the uncertainty of the measurement time length is reduced, the accuracy of the measurement time length is improved, and the accuracy of calibrating the critical flow Venturi nozzle to be calibrated through a quality-time length method is further improved.
In step 205, the critical flow venturi nozzle to be calibrated is calibrated according to the actual measurement time and the measured gas mass.
In a possible embodiment, after the actual measurement duration is obtained through the above steps, the outflow coefficient of the venturi nozzle to be calibrated is calculated through the actual measurement duration and the measured gas mass and through a calculation formula of the outflow coefficient of the critical flow venturi nozzle, and the critical flow venturi nozzle to be calibrated is calibrated.
Experiments show that after the actual measurement time length is obtained by correcting the initial measurement time length, when the critical flow venturi nozzle to be calibrated is calibrated by a mass-time length method, the uncertainty of the calculated mass flow reaches 0.10% (k is 2), and the measurement standard assessment of the State quality and technology supervision Bureau is passed.
In the embodiment of the invention, the error time length is obtained by calculating through an error test, when the critical flow venturi nozzle to be calibrated is calibrated, the real measurement time length is calculated according to the obtained initial measurement time length and the error time length, and then the critical flow venturi nozzle to be calibrated is calibrated according to the real measurement time length and the measured gas mass. Therefore, the initial measurement time length is corrected through the error time length, the obtained real measurement time length is more accurate, and further, the result of calibrating the critical flow venturi nozzle can be more accurate.
Based on the same technical concept, the embodiment of the present invention further provides a device for calibrating a critical flow venturi nozzle, which may be a terminal in the above embodiment, as shown in fig. 4, and the device includes: an acquisition module 410, a determination module 420, a measurement module 430, a calculation module 440, and a calibration module 450.
The obtaining module 410 is configured to obtain a total initial measurement duration of a total error test, an initial measurement duration of a fractional error test, and a test number of the fractional error test;
the determining module 420 is configured to determine an error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, and the test times of the fractional error test;
the measurement module 430 is configured to acquire an initial measurement duration of the critical flow venturi nozzle to be calibrated, and measure a mass of gas flowing through the critical flow venturi nozzle to be calibrated during the initial measurement duration; the initial measurement duration is a timing duration obtained from starting timing to stopping timing in the process that gas flows through the critical flow venturi nozzle to be calibrated;
the calculating module 440 is configured to calculate a difference obtained by subtracting the error duration from the initial testing duration to obtain a real measuring duration;
the calibration module 450 is configured to calibrate the critical flow venturi nozzle to be calibrated according to the actual measurement time and the measured gas mass.
Optionally, the obtaining module 410 is further configured to:
acquiring total initial measurement time of a total error test, initial measurement time of a fractional error test, test times of the fractional error test and a measurement parameter ratio of the total error test to the fractional error test;
the determining module 420 is further configured to:
and determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test and the measurement parameter ratio of the total error test to the fractional error test.
Optionally, the obtaining module 410 is further configured to:
acquiring the total initial measurement time length of a total error test, the gas mass and the gas molar mass in the total error test, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle;
acquiring the initial measurement duration of a fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test;
and determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
Optionally, the determining module 420 is further configured to:
according to the following formula, the error duration is calculated,
wherein, Deltat is the error duration, B is the ratio of the measurement parameters, t' is the initial measurement duration of the fractional error test, t1And n is the test times of the fractional error tests.
Optionally, the measurement module 430 is configured to:
when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment;
when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment;
when the second reversing valve is closed to the preset angle, timing is stopped;
determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length;
determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
In the embodiment of the invention, the error time length is obtained by calculating through an error test, when the critical flow venturi nozzle to be calibrated is calibrated, the real measurement time length is calculated according to the obtained initial measurement time length and the error time length, and then the critical flow venturi nozzle to be calibrated is calibrated according to the real measurement time length and the measured gas mass. Therefore, the initial measurement time length is corrected through the error time length, the obtained real measurement time length is more accurate, and further, the result of calibrating the critical flow venturi nozzle can be more accurate.
With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.
It should be noted that: the device for calibrating the critical flow venturi nozzle provided in the above embodiment is only illustrated by dividing the functional modules when calibrating the critical flow venturi nozzle, and in practical applications, the function distribution may be completed by different functional modules according to needs, that is, the internal structure of the apparatus may be divided into different functional modules to complete all or part of the functions described above. In addition, the device for calibrating the critical flow venturi nozzle provided by the above embodiment and the method embodiment for calibrating the critical flow venturi nozzle belong to the same concept, and the specific implementation process thereof is detailed in the method embodiment and is not described herein again.
Fig. 5 is a schematic structural diagram of a computer device according to an embodiment of the present invention, where the computer device may be a terminal in the foregoing embodiment. The computer device 500 may have a relatively large difference due to different configurations or performances, and may include one or more processors (CPUs) 501 and one or more memories 502, wherein the memory 502 stores at least one instruction, and the at least one instruction is loaded and executed by the processor 501 to implement the following method steps for calibrating the critical flow venturi nozzle:
acquiring total initial measurement time of a total error test, initial measurement time of a fractional error test and test times of the fractional error test;
determining error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test and the test times of the fractional error test;
acquiring initial measurement time of a critical flow Venturi nozzle to be calibrated, and measuring the mass of gas flowing through the critical flow Venturi nozzle to be calibrated in the initial measurement time; the initial measurement duration is a timing duration obtained from starting timing to stopping timing in the process that gas flows through the critical flow venturi nozzle to be calibrated;
calculating a difference value obtained by subtracting the error time length from the initial test time length to obtain a real measurement time length;
and calibrating the critical flow venturi nozzle to be calibrated according to the real measuring time length and the measured gas mass.
Optionally, the at least one instruction is loaded and executed by the processor 501 to implement the following method steps:
acquiring the total initial measurement time of a total error test, the initial measurement time of a fractional error test, the test times of the fractional error test and the measurement parameter ratio of the total error test to the fractional error test.
Optionally, the at least one instruction is loaded and executed by the processor 501 to implement the following method steps:
and determining the error duration according to the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the test times of the fractional error test and the measurement parameter ratio of the total error test to the fractional error test.
Optionally, the at least one instruction is loaded and executed by the processor 501 to implement the following method steps:
acquiring the total initial measurement time length of a total error test, the gas mass and the gas molar mass in the total error test, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle;
acquiring the initial measurement duration of a fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test;
and determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
Optionally, the at least one instruction is loaded and executed by the processor 501 to implement the following method steps:
according to the following formula, the error duration is calculated,
wherein, Deltat is the error duration, B is the ratio of the measurement parameters, t' is the initial measurement duration of the fractional error test, t1And n is the test times of the fractional error tests.
Optionally, the at least one instruction is loaded and executed by the processor 501 to implement the following method steps:
when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment;
when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment;
when the second reversing valve is closed to the preset angle, timing is stopped;
determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length;
determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
In the embodiment of the invention, the error time length is obtained by calculating through an error test, when the critical flow venturi nozzle to be calibrated is calibrated, the real measurement time length is calculated according to the obtained initial measurement time length and the error time length, and then the critical flow venturi nozzle to be calibrated is calibrated according to the real measurement time length and the measured gas mass. Therefore, the initial measurement time length is corrected through the error time length, the obtained real measurement time length is more accurate, and further, the result of calibrating the critical flow venturi nozzle can be more accurate.
In an exemplary embodiment, a computer readable storage medium is also provided, in which at least one instruction, at least one program, code set, or instruction set is stored, and the at least one instruction, the at least one program, the code set, or the instruction set is loaded and executed by a processor to implement the method for identifying an action category in the above embodiments. For example, the computer readable storage medium may be a ROM, a Random Access Memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. A method of calibrating a critical flow venturi nozzle, the method comprising:
obtaining the total initial measurement time t of the total error test1The method comprises the following steps of (1) carrying out a fractional error test on the total error test and the fractional error test, wherein the fractional error test comprises the initial measurement time t', the test times n and the measurement parameter ratio B of the total error test and the fractional error test;
according to the total initial measurement time t of the total error test1Station, stationDetermining an error time length delta t by the initial measurement time length t' of the fractional error test, the test times n of the fractional error test and the measurement parameter ratio B of the total error test to the fractional error test, wherein the adopted formula is as follows:
acquiring initial measurement time of a critical flow Venturi nozzle to be calibrated, and measuring the mass of gas flowing through the critical flow Venturi nozzle to be calibrated in the initial measurement time; the initial measurement duration is a timing duration obtained from starting timing to stopping timing in the process that gas flows through the critical flow venturi nozzle to be calibrated;
calculating a difference value obtained by subtracting the error time length from the initial test time length to obtain a real measurement time length;
and calibrating the critical flow venturi nozzle to be calibrated according to the real measuring time length and the measured gas mass.
2. The method of claim 1, wherein the obtaining of the total initial measurement duration of the total error test, the initial measurement duration of the fractional error test, the number of tests of the fractional error test, and the ratio of the measurement parameters of the total error test to the fractional error test comprises:
acquiring the total initial measurement time length of a total error test, the gas mass and the gas molar mass in the total error test, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle;
acquiring the initial measurement duration of a fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test;
and determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
3. The method of claim 1, wherein the obtaining an initial measurement duration for the critical flow venturi nozzle to be calibrated and measuring a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration comprises:
when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment;
when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment;
when the second reversing valve is closed to the preset angle, timing is stopped;
determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length;
determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
4. An apparatus for calibrating a critical flow venturi nozzle, comprising:
an obtaining module for obtaining the total initial measurement time t of the total error test1The initial measurement time t' of the fractional error test, the test times n of the fractional error test and the totalThe ratio B of the measurement parameters of the error test and the fractional error test;
a determination module for determining the total initial measurement time t according to the total error test1Determining an error time length delta t by the initial measurement time length t' of the fractional error test, the test times n of the fractional error test and the measurement parameter ratio B of the total error test to the fractional error test, wherein the adopted formula is as follows:
the measuring module is used for acquiring the initial measuring time length of the critical flow Venturi nozzle to be calibrated and measuring the mass of gas flowing through the critical flow Venturi nozzle to be calibrated in the initial measuring time length; the initial measurement duration is a timing duration obtained from starting timing to stopping timing in the process that gas flows through the critical flow venturi nozzle to be calibrated;
the calculation module is used for calculating a difference value obtained by subtracting the error time length from the initial test time length to obtain a real measurement time length;
and the calibration module is used for calibrating the critical flow venturi nozzle to be calibrated according to the real measurement time length and the measured gas quality.
5. The apparatus of claim 4, wherein the obtaining module is further configured to:
acquiring the total initial measurement time length of a total error test, the gas mass and the gas molar mass in the total error test, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle;
acquiring the initial measurement duration of a fractional error test, the test times of the fractional error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test;
and determining the ratio of the measurement parameters of the total error test and the fractional error test according to the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition, the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the total error test, and the gas mass, the gas molar mass, the stagnation temperature at the upstream inlet of the critical flow Venturi nozzle, the critical flow function under the stagnation condition and the stagnation pressure at the upstream inlet of the critical flow Venturi nozzle in the fractional error test.
6. The apparatus of claim 4, wherein the measurement module is configured to:
when the first reversing valve is closed to a preset angle, timing is started, and the second reversing valve is opened, so that gas flows into the gas quality detection equipment;
when the timed duration reaches the preset duration, the second reversing valve is closed, so that the gas stops flowing into the gas quality detection equipment;
when the second reversing valve is closed to the preset angle, timing is stopped;
determining the time length obtained from the start of timing to the stop of timing as the initial measurement time length;
determining, by the gas mass detection device, a mass of gas flowing through the critical flow venturi nozzle to be calibrated within the initial measurement duration.
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| EP2581714A1 (en) * | 2011-10-12 | 2013-04-17 | systec Controls Mess- und Regeltechnik GmbH | Method for determining an absolute flow velocity of a volume or mass flow |
| WO2013130003A1 (en) * | 2012-03-01 | 2013-09-06 | Väderstad-Verken Ab | Method for calibrating a device for feeding a granular or powder material and such device |
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