A remote control method for natural gas flowmeter

Abstract

The present invention discloses a method for remotely controlling a natural gas flowmeter. The diagnostic function includes the following steps: S1: a remote database server controls a digital diagnostic module to switch the function to a diagnostic state; S2: the digital diagnostic module reads the static and dynamic parameters of the flowmeter; S3: the digital diagnostic module combines the read static and dynamic parameters, calculates the theoretical flow rate through a processor in the diagnostic module, and verifies the flowmeter's displayed flow rate. The present invention also includes a calibration function. The flowmeter diagnosed and calibrated by the present method communicates bidirectionally with the digital diagnostic module via a fieldbus, and remote bidirectional communication is achieved between the digital diagnostic module and the database server via a production network.

Description

Technical Field

[0001] The present invention belongs to the field of natural gas metering and automatic control technology, and specifically relates to a remote control method for natural gas flowmeters. This method uses a digital diagnostic module to remotely diagnose intelligent velocity-type natural gas flowmeters and perform online calibration of intelligent velocity-type and differential pressure-type natural gas flowmeters. Background Art

[0002] Natural gas flow measurement is achieved through flow measurement and gas quality analysis. Accurately measuring natural gas is challenging because it is measured while in motion and exhibits significant compressibility and expansibility. However, by taking appropriate measures to accurately measure volumetric flow, pipeline pressure, temperature, and gas quality composition, the standard volumetric flow rate can be calculated according to relevant standards. Pulse-output velocity flowmeters are a primary method for measuring natural gas volumetric flow. They automatically acquire fluid pressure and temperature and calculate the standard volumetric flow rate in real time. They can display the pressure, temperature, standard condition, or operating condition of the measured medium on-site, allowing for storage and transmission. However, there are numerous types of flowmeters currently available on the market, each equipped with a different flow sensor (transmitter), pressure sensor (transmitter), and temperature sensor (transmitter). The gas quality composition standards used by flowmeters and the flow calculation formulas employed may also vary. Flowmeter manufacturers claim their products offer powerful signal processing, data storage, and fault self-diagnosis capabilities. However, in actual field use, the self-diagnosis features of flowmeters are largely unutilized due to varying measurement requirements and the limitations of various on-site operating conditions. Summary of the Invention

[0003] The object of the present invention is to provide a natural gas flow meter remote control method, which controls a digital diagnosis module through a database server to perform remote diagnosis and calibration on the natural gas flow meter.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A natural gas flow meter remote control method comprises the following steps:

[0006] S1 remote database server controls the digital diagnosis module to switch the function to the diagnosis state;

[0007] S2 digital diagnostic module reads the static and dynamic parameters of the flow meter;

[0008] The S3 digital diagnostic module combines the static and dynamic parameters it reads, calculates the theoretical flow rate through the diagnostic module's processor, and verifies the flow rate displayed by the flowmeter.

[0009] In the above step S2, the static parameter diagnosis includes:

[0010] S2-1 Temperament Component Diagnosis:

[0011] S2-2 flowmeter structural parameter coefficient diagnosis;

[0012] S2-3 flow range diagnosis;

[0013] The above S2-1 temperament component diagnosis includes

[0014] The S2-1-1 static parameter module obtains the effective gas quality components of the natural gas with the same gas source and uploads them to the data

[0015] The database server or the database server writes the effective temperament components;

[0016] The S2-1-2 static parameter module reads the gas composition in the flow meter and uploads it to the database server. The database server calculates whether the molar composition is normalized, the natural gas compressibility factor, density and high-volume calorific value, and stores them;

[0017] The database server in step S2-1-3 determines whether the gas composition of the flow meter is consistent with the effective gas composition. If so, it proceeds to step S2-1-5. If not, it proceeds to step S2-1-4.

[0018] S2-1-4 database server alarm, after verification, authorization and confirmation, the gas composition of the flow meter can be remotely modified to be consistent through the database server;

[0019] The database server in S2-1-5 monitors whether the modification interval of the gas composition of the flow meter exceeds the set period; if it exceeds, an alarm is issued, and after verification and authorization, the gas composition in the flow meter is diagnosed;

[0020] S2-1-6 The database server automatically saves the first read or modification time as the start time of this cycle;

[0021] The above S2-2 flowmeter structural parameter diagnosis steps include:

[0022] S2-2-1 static parameter module reads the flow meter K coefficient and segmented flow error value, uploads them to the database server or writes the verified effective flow meter K coefficient into the database server as a standard parameter for storage, and records the reading time as the start time of the effective period;

[0023] The S2-2-2 static parameter module reads the real-time flow meter K coefficient once a day and uploads it to the database server to determine whether the K coefficient is consistent with the standard parameter. If it is inconsistent, an alarm will be issued; after verification, authorization, and confirmation, the gas composition in the flow meter can be remotely modified through the database server;

[0024] The database server in S2-2-3 monitors whether the K-factor operation cycle of the flowmeter exceeds the verification cycle: prompts the flowmeter that is about to expire; and alarms the flowmeter that has exceeded the verification cycle time;

[0025] S2-2-4 The database server also saves the most recently modified K coefficient as a new standard parameter for the next cycle diagnosis;

[0026] The above S2-3 flow range diagnosis includes

[0027] S2-3-1 static parameter module reads the flow meter flow range and uploads it to the database server or enters the flow range through the database server;

[0028] The database server described in S2-3-2 monitors the real-time flow rate daily; when the low-limit flow rate is lower than the lower limit setting value of the flow range, the low-limit operation time point and the accumulated time are recorded and an alarm is issued; when the high-limit flow rate is higher than the upper limit setting value of the flow range, the ultra-high limit operation time point and the accumulated time are recorded and an alarm is issued;

[0029] The database server described in S2-3-3 automatically generates a monthly dynamic report on over-limit flow operation based on the over-limit operation time point and cumulative time, and adjusts the applicable status of the flow meter when necessary to reduce the measurement loss caused by the negative deviation caused by over-limit operation and over-limit operation;

[0030] In step S2, dynamic parameter diagnosis includes:

[0031] The S2-4-1 flow meter collects flow pressure, temperature, output pulse, and instantaneous flow in real time;

[0032] The S2-4-2 dynamic parameter diagnosis module continuously reads the flow meter output pressure, temperature, output pulse, and instantaneous flow under standard conditions, and uploads them to the database server;

[0033] The S2-4-2 database server selects the monitored parameters, such as pressure, temperature, output pulse, and instantaneous flow under standard conditions, sets a date range, and uses the recursive average filter algorithm model and the regional limit evaluation method to calculate the upper and lower limits of the parameters to generate a dynamic trend operating range within the date range. This allows for real-time monitoring of the production status and provides an alarm when an abnormality occurs.

[0034] Said step S3 specifically includes the following steps:

[0035] The diagnostic module's processor calculates the theoretical flow rate and verifies the flow rate displayed by the flowmeter; including:

[0036] S3-1 dynamic parameter interrupt module reads the real-time output pulse, pressure, and temperature of the flow meter, and combines the static parameter effective flow meter K coefficient obtained in step S2-2-1 and the effective gas quality components obtained in step S2-1-1, and the central processing unit calculates the theoretical standard instantaneous flow rate of natural gas;

[0037] The S3-2 digital diagnostic module reads the instantaneous flow rate displayed by the flow meter under standard conditions;

[0038] The central processing unit of the S3-3 digital diagnostic module compares the theoretical instantaneous flow rate under standard conditions with the instantaneous flow rate under standard conditions displayed by the flow meter. The digital diagnostic module uploads the comparison results to the database server; if the error exceeds the maximum allowable error, an alarm is issued;

[0039] Specifically, the calculation method of instantaneous flow under theoretical standard conditions is as follows:

[0040]

[0041] Where: q n —Theoretical instantaneous volume flow rate calculated by the server under standard conditions, m 3 / s;

[0042] q g —Theoretical instantaneous volume flow calculated by the server in working state, m 3 / s;

[0043] P g —Absolute pressure of natural gas in working state collected by flowmeter, kPa;

[0044] P n —Standard atmospheric pressure, 101.325 kPa;

[0045] T n — Absolute temperature under standard conditions, 293.15K or 273.15K;

[0046] T g —Absolute temperature of natural gas in working state collected by flow meter, K;

[0047] Z n —Compression coefficient of natural gas under standard conditions;

[0048] Z g —Compression coefficient of natural gas under working conditions.

[0049] The remote control method of the natural gas flow totalizer of the present invention also includes an automatic calibration method for indication error, comprising the following steps:

[0050] The S4 remote database server controls the digital diagnostic module to switch the function to the calibration state;

[0051] The S5 standard signal source outputs standard signals to the flowmeter, such as standard current, voltage, frequency, pulse, digital signal, etc.

[0052] The S6 flow meter receives the signal to display the corresponding flow rate and outputs the corresponding signal to the diagnostic module;

[0053] The S7 diagnostic module reads the flow meter output signal, and the central processing unit calculates the flow meter indication error;

[0054] The calculation method of the instantaneous flow indication error of S7-1 flowmeter is as follows:

[0055] When the S7-1-1 flowmeter is in working condition, set the compensation pressure and temperature, and select inspection points near the lower limit of the flow range of the flow sensor, 0.25 times, 0.5 times, 0.75 times, and 1 times the maximum instantaneous flow rate;

[0056] In addition, when the pressure is constant and the temperature is within the flow range, select two test points at random, and the flow rate is maximum; when the temperature is constant and the pressure is within the design range, select two test points at random, and the flow rate is maximum; perform calibration respectively;

[0057] S7-1-2 presses the selected inspection point, the standard signal source outputs flow, pressure and temperature signals simultaneously, the flow meter measures the signal and displays the instantaneous flow value;

[0058] The S7-1-3 calibration module calculates the error E of each check point according to the following formula i , if the error E i If the error exceeds the allowable range, an alarm will be issued;

[0059]

[0060] Where: q i —Select the flow meter at the inspection point to display the instantaneous flow value, m 3 / s or kg / s;

[0061] q si —Select the theoretical instantaneous flow value calculated by the calibration module at the check point, m 3 / s or kg / s;

[0062] For velocity flowmeters with pulse output signals:

[0063]

[0064] Where: f i —Select the standard frequency signal output by the standard signal source at the test point, 1 / s;

[0065] K—Flow meter K coefficient, 1 / L or 1 / m 3 ;

[0066] For differential pressure flowmeter:

[0067]

[0068] In the formula: C—outflow coefficient;

[0069] β—Ratio of the throttling device opening diameter to the upstream pipe inner diameter under operating conditions, β=d / D;

[0070] ε—expansion coefficient;

[0071] d—diameter of the throttle hole or throat of the throttle under working conditions, mm;

[0072] Δp i —Select the standard differential pressure output by the standard signal source at the inspection point, Pa;

[0073] ρ—Natural gas density under working conditions, kg / m 3 ;

[0074] Except for the differential pressure, all other parameters on the right side of the equal sign in the formula are obtained by reading the flow meter by the diagnostic module;

[0075] The calculation method of the S7-2 flowmeter cumulative flow indication error is as follows:

[0076] S7-2-1 flow meter calibration point within the flow range;

[0077] S7-2-2 presses the selected inspection point, the standard signal source outputs the flow signal, and the flow meter receives the signal; after the signal stabilizes, the timing starts, and the calibration module reads the time t within which the flow meter displays the cumulative flow Q under the working condition i ;

[0078] The S7-2-3 calibration module calculates the error E of the cumulative flow indication under working conditions within time t according to the following formula Q , if the error E Q If the error exceeds the allowable range, an alarm will be issued;

[0079]

[0080] Where: Q i —The flow meter displays the cumulative flow rate during the working condition within t time, m 3 or kg;

[0081] Q si —Theoretical cumulative flow rate m within time t calculated by the calibration module 3 or kg;

[0082] For velocity flowmeters with pulse output signals:

[0083]

[0084] Where: N—the number of frequency pulses output by the time standard signal source (the uncertainty introduced by the pulse resolution should be better than 1 / 10 of the maximum allowable error);

[0085] For differential pressure flowmeter:

[0086]

[0087] The calculation method of the S7-3 flowmeter cumulative energy indication error is as follows:

[0088] S7-3-1 Calibration of cumulative energy error E w Calculate as follows:

[0089]

[0090] Where: W i —The flow meter displays the accumulated energy, MJ or kWh;

[0091] W si —The calibration module calculates the theoretical cumulative flow rate, MJ or kWh (according to the method specified in GB / T 11062);

[0092] The calculation method of the compensation parameter display error of the S7-4 flowmeter is as follows:

[0093] S7-4-1 experimental point is zero point, 0.25A max , 0.5A max , 0.75A max 、A max ;

[0094] S7-4-2 presses the selected inspection point, the standard signal source outputs the pressure or temperature signal, the flow meter receives the signal and measures and displays it;

[0095] S7-4-3 Calculate the error E of the selected inspection point according to the following formula Ai (The error should meet the maximum allowable error requirements of the corresponding accuracy level). If the error exceeds the allowable error range, an early warning will be prompted;

[0096]

[0097] Where: A i —Flow meter indication, Pa or °C;

[0098] A si —Select the theoretical calculated value corresponding to the output signal of the standard signal source at the inspection point, Pa or °C;

[0099] A max —The theoretically calculated maximum value corresponding to the output signal of the standard signal source, Pa or °C;

[0100] For temperature signal A max Take the upper temperature limit of the design task book;

[0101]

[0102] In the formula: C—outflow coefficient;

[0103] β—Ratio of the throttling device opening diameter to the upstream pipe inner diameter under operating conditions, β=d / D;

[0104] ε—expansion coefficient;

[0105] d—diameter of the throttle hole or throat of the throttle under working conditions, mm;

[0106] Δp i —Select the standard differential pressure output by the standard signal source at the inspection point, Pa;

[0107] ρ—Natural gas density under working conditions, kg / m 3 ;

[0108] Except for the differential pressure, all other parameters on the right side of the equal sign in the formula are obtained by reading the flow meter by the diagnostic module.

[0109] The flow meter diagnosed and calibrated by the method of the present invention performs two-way communication with the digital diagnosis module via a field bus and relies on a database server that performs remote two-way communication with the digital diagnosis module over a production network.

[0110] The digital diagnostic module includes a central processing unit (CPU), a static parameter module, a dynamic parameter module, a standard signal source, and a power supply, all connected to the CPU. These modules, used individually or in combination, can perform static and dynamic parameter diagnosis, flow rate verification, and flowmeter indication error calibration.

[0111] The diagnostic functions of the static module include gas composition diagnosis, flow meter K coefficient diagnosis and flow range diagnosis; the input end of the static parameter module is connected to the output end of the flow meter, used to read the gas composition, flow meter K coefficient and flow range in the flow meter, and the output end is electrically connected to the central processing unit. The central processing unit diagnoses the static parameters and uploads the diagnostic results to the database server to realize information exchange.

[0112] The dynamic parameter module functions include pressure, temperature, instantaneous flow rate, and output pulse diagnosis. The dynamic parameter input terminal is connected to the flow meter output terminal to read the flow meter's real-time pressure, temperature, instantaneous flow rate, and output pulse. The output terminal is connected to the central processing unit. The central processing unit uploads the dynamic parameters to the database server to generate a dynamic trend curve.

[0113] The central processing unit will obtain the real-time pressure, temperature, and output pulse of the flow meter, and combine it with the effective gas quality parameters and the flow meter K number in the static parameter module. The central processing unit will use the built-in flow measurement formula to verify the real-time flow displayed by the flow meter, and upload the flow verification results to the database service.

[0114] The standard signal source selects appropriate signals such as standard current, voltage, frequency, pulse, digital signal, etc. according to the flowmeter signal requirements to output standard signals, and the flowmeter receives the signal and outputs the corresponding signal; the dynamic parameter module reads the flowmeter output signal, and calculates the instantaneous flow indication error, the cumulative flow indication error and the compensation parameter indication error through the built-in indication error calculation signal of the central processing unit, and uploads the diagnosis results to the database service.

[0115] Connect the flow meter to the digital diagnosis module, and control the digital diagnosis module through the database server to perform remote diagnosis and online calibration on the flow meter.

[0116] When the flowmeter is operating normally, the database server switches the digital diagnostic module to diagnostic mode. The flowmeter collects natural gas dynamic parameters in real time and calculates the smooth flow rate for display. The digital diagnostic module reads the flowmeter's static and dynamic parameters for diagnosis. Simultaneously, the central processing unit calculates the theoretical flow rate using the flow calculation formula built into the flowmeter according to the technical requirements of the natural gas metering system and the relevant standards for the calculation of the natural gas compression factor, and verifies the flow rate displayed on the integrator.

[0117] When the flowmeter stops production, the database server switches the digital diagnostic module function to signal calibration. Referring to the JJG1003 calibration method, the digital diagnostic module's standard signal source sends a standard signal to the integrator. The integrator collects the standard signal and then returns it to the diagnostic module. The diagnostic module calculates the flow integrator's instantaneous flow indication error, cumulative flow (energy) indication error, and compensation parameter indication error using the built-in calculation formula in the central processing unit. The module then checks whether the diagnostic signal indication error is within the allowable range.

[0118] The communication module is electrically connected to the central processing unit and is used to realize communication with the database server; the power supply part uses an external power supply to supply power to the diagnosis module.

[0119] The method provided by the present invention has the following technical effects:

[0120] (1) Through the diagnosis of gas quality parameters and flow meter K coefficient, it is possible to monitor whether the gas quality parameters and flow meter K coefficient of the flow meter are consistent with the test report or calibration certificate, whether the over-cycle operation has not been modified, and whether there has been any unauthorized tampering, so as to eliminate the measurement error caused by incorrect parameters.

[0121] (2) Through the diagnosis of the flow range, a monthly dynamic report on over-limit flow operation can be automatically generated on a monthly basis. The management personnel can analyze the monthly report to grasp the seasonal gas consumption characteristics and daily gas consumption characteristics of users in real time, and adjust the applicable status of the flow meter in time to reduce the metering loss caused by the negative deviation caused by over-limit operation and over-limit operation.

[0122] (3) The operating range of the flow dynamic trend curve generated by dynamic parameter diagnosis has the characteristics of narrow bandwidth and high sensitivity compared with the traditional operating range generated by design parameters, which can detect and deal with problems in a timely and efficient manner.

[0123] (4) Traditional laboratory calibration of flow totalizers requires disassembling the flowmeter and sending it to a calibration agency for calibration. Calibration requires many standards and the calculation method is complex, which is not conducive to manual calculation. By performing online calibration of flow totalizers, the inspection process can be simplified, the workload can be reduced, and the level of measurement management can be improved.

[0124] In general, the present invention proposes unified requirements for the diagnostic content of this type of natural gas flowmeter, forming a complete set of flowmeter remote diagnosis and online calibration methods, which is particularly suitable for pulse output velocity flowmeters installed in natural gas applications.

[0125] This method can diagnose whether the static parameter settings of the flow meter are effective, whether the operating range of the dynamic parameters is reasonable, and whether the flow calculation model meets the corresponding standard requirements; it can also perform online calibration of the flow meter to solve the problems of multiple standards required for laboratory verification, complex calculation methods, and inconvenience of manual calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0126] Figure 1 This is a schematic diagram of the present invention in use;

[0127] Figure 2 This is a functional structure diagram of the present invention; DETAILED DESCRIPTION

[0128] The present invention will be described in further detail below with reference to the accompanying drawings.

[0129] Example 1

[0130] like Figure 1 、 2 A natural gas flow meter remote control method shown may include the following steps:

[0131] The remote database server controls the digital diagnosis module to switch the function to the diagnosis state;

[0132] The digital diagnosis module reads the static and dynamic parameters of the flow meter integrator and performs diagnosis;

[0133] The digital diagnostic module combines the static and dynamic parameters read, calculates the theoretical flow rate through the diagnostic module central processor, and verifies the flow rate displayed by the integrator.

[0134] Specifically, the temperament component diagnosis logic of the static parameter module is:

[0135] (1) The static parameter module obtains the effective gas quality components of natural gas of the same gas source and uploads them to the database server or writes the effective gas quality components through the database server;

[0136] (2) The static parameter module reads the gas composition in the integrator and uploads it to the database service. The database server calculates whether the molar composition is normalized, the natural gas compressibility factor, density and high-volume calorific value according to GB / T17747.1-3 and saves the calculation results.

[0137] (3) The database server determines whether the gas composition of the integrator is consistent with the effective gas composition. If not, a red warning "gas composition abnormality" will flash. After verification, authorization, and confirmation, the gas composition in the flow meter integrator can be remotely modified through the database server; at the same time, the server automatically saves the first reading or modification time as the start time of this cycle (and so on).

[0138] (4) The database server monitors whether the modification interval between the current reading time and the start time of the gas composition of the flow meter exceeds three months. If so, a red flashing "gas composition over period" alarm is issued. After verification and authorization, the gas composition in the flow meter integrator is diagnosed;

[0139] Specifically, the flowmeter structural parameter diagnosis logic of the static parameter module is:

[0140] The static parameter module reads the K coefficient of the flow meter of the integrator (the K coefficient of the flow meter is a constant related only to the structural parameters of the instrument, obtained by experimental calibration, and each flow meter corresponds to a unique K coefficient) and the segmented flow error value and uploads them to the database server or writes the verified effective flow meter K coefficient through the database server as a standard parameter for storage, and records the reading time as the starting time of the effective period (the verification period of the flow meter is generally 2 years, and the verification period of the flow meter with an accuracy level of not less than 0.5 is 1 year);

[0141] (2) The static parameter module reads the real-time flow meter K coefficient once a day and uploads it to the database server to determine whether the flow coefficient K coefficient is consistent with the standard parameter. If it is inconsistent, a red flashing "Instrument coefficient K abnormality" warning is displayed to prevent unauthorized modification of parameters;

[0142] (3) The database server monitors whether the K coefficient operation cycle of the flow meter exceeds the calibration cycle: the flow meter that is about to expire should display the red flashing words "calibration cycle" at least one month in advance as a warning; if the calibration cycle time has been exceeded, the red flashing words "calibration cycle abnormality" will be displayed as an alarm; the database server also saves the most recently modified K coefficient as a new standard parameter for the next cycle diagnosis.

[0143] Specifically, the flow range diagnostic logic of the static parameter module is:

[0144] (1) The static parameter module reads the flow range of the flow meter and uploads it to the database server or enters the flow range through the database server;

[0145] (2) The database server monitors the real-time traffic flow daily. When the low-limit traffic flow is lower than the lower limit of the traffic range, the low-limit operation time point and the accumulated time are recorded and a red "low-limit traffic flow" warning is flashing; when the high-limit traffic flow is higher than the upper limit of the traffic range, the ultra-high-limit operation time point and the accumulated time are recorded and a red "high-limit traffic flow" warning is flashing;

[0146] (3) The database server automatically generates a monthly dynamic report on over-limit flow operation based on the over-limit operation time point and cumulative time. The management personnel analyze the monthly report to grasp the seasonal gas consumption characteristics and daily gas consumption characteristics of users in real time, and adjust the applicable status of the flow meter when necessary to reduce the metering loss caused by the negative deviation caused by over-limit operation and over-limit operation.

[0147] Specifically, the dynamic parameter module diagnostic logic is:

[0148] The integrator collects flow pressure, temperature, output pulse, and instantaneous flow under standard conditions in real time;

[0149] The dynamic parameter diagnosis module continuously reads (once per minute) the integrator output pressure, temperature, output pulse, and instantaneous flow under standard conditions, which are uploaded to the database server via the central processing unit;

[0150] (3) The database server selects monitored parameters such as pressure, temperature, output pulse, instantaneous flow under standard conditions, and sets a date range. Based on the recursive average filtering algorithm model and the regional limit evaluation method, the upper and lower limit values ​​of the parameters are calculated to generate a dynamic trend operating range within the date range (compared to the traditional operating range generated by design parameters, this operating range has the characteristics of narrow bandwidth and high sensitivity). The production status is monitored in real time and an early warning is issued when an abnormality occurs.

[0151] The digital diagnostic module combines the dynamic parameter module and the static parameter module to verify the flow displayed on the integrator using the built-in flow calculation formula of the central processing unit, including the following steps:

[0152] The dynamic parameter module reads the real-time output pulse, pressure, and temperature of the flow meter, and combines the effective flow meter K coefficient and effective gas quality parameters of the static parameters, etc. The central processing unit calculates the theoretical standard instantaneous flow rate of natural gas according to the relevant standard calculation model through the built-in calculation formula;

[0153] The digital diagnostic module reads the instantaneous flow rate displayed on the integrator under standard conditions;

[0154] The central processing unit of the digital diagnosis module compares the theoretical standard condition instantaneous flow rate with the standard condition instantaneous flow rate displayed by the integrator. The error should be less than the maximum allowable error.

[0155] The digital diagnosis module uploads the comparison results to the database server.

[0156] Specifically, the calculation method of instantaneous flow under theoretical standard conditions is as follows:

[0157]

[0158] Where: q n —Theoretical instantaneous volume flow rate calculated by the server under standard conditions, m 3 / s;

[0159] q g —Theoretical instantaneous volume flow calculated by the server in working state, m 3 / s;

[0160] P g —Absolute pressure of natural gas under working condition collected by the integrator, kPa;

[0161] P n —Standard atmospheric pressure, 101.325 kPa;

[0162] T n — Absolute temperature under standard conditions, 293.15K or 273.15K;

[0163] T g —Absolute temperature of natural gas in working state collected by integrator, K;

[0164] Z n —Compression coefficient of natural gas under standard conditions;

[0165] Z g —Compression coefficient of natural gas under working conditions;

[0166] When the natural gas metering system meets the accuracy Class C requirement specified in GB / T 18603, the server calculates the natural gas compressibility coefficient according to AGANX-19, and the diagnostic module directly reads the structural parameters K or C, d, β, and ε in the integrator.

[0167] When the natural gas metering system meets the accuracy requirements of Class A and B specified in GB / T 18603, the natural gas compressibility coefficient shall be calculated in accordance with GB / T11747.1-3; the structural parameters C and ε of the differential pressure flowmeter shall be calculated in accordance with GB / T 2624.

[0168] Example 2

[0169] The remote control method of the natural gas flow totalizer of the present invention also includes an automatic calibration method for indication error, which may specifically include the following steps:

[0170] The remote database server controls the diagnostic module to switch the function to the calibration state;

[0171] The standard signal source selects appropriate signals such as standard current, voltage, frequency, pulse, digital signal, etc. according to the signal requirements of the integrator to output standard signals;

[0172] The integrator receives the signal and outputs the corresponding displayed flow rate;

[0173] The diagnostic module reads the output signal of the integrator, and the central processing unit calculates the error of the integrator indication using a built-in calculation formula.

[0174] Specifically, the calculation method of the instantaneous flow indication error of the integrator is as follows:

[0175] (1) Under the designed working state of the integrator, set the flow range of the flow sensor (or transmitter) corresponding to the input signal (frequency signal f for velocity flowmeter) under the compensation pressure and temperature (standard pressure and temperature or set to common fixed values ​​according to user requirements) i , differential pressure flowmeter is differential pressure signal Δp i ) of the range, 0.25 times, 0.5 times, 0.75 times, and 1 times of the range limit; in addition, calibration should be carried out under the conditions that the pressure remains unchanged, the temperature is within the design range, and the flow rate is maximum at any two points; the temperature remains unchanged, the pressure is within the design range, and the flow rate is maximum at any two points.

[0176] (2) According to the selected inspection point, the standard signal source outputs flow, pressure and temperature signals simultaneously, and the integrator measures the signal and displays the instantaneous value.

[0177] (3) The calibration module calculates the error E of each point according to the following formula i (The error should meet the maximum allowable error requirements of the corresponding accuracy level, such as the maximum allowable error of a level 1.0 integrator is ±1.0%). If the error E i If the error exceeds the allowable range, an alarm will be triggered.

[0178]

[0179] Where: q i—Select the check point where the integrator displays the instantaneous value, m 3 / s or kg / s;

[0180] q si —Select the theoretical instantaneous value calculated by the calibration module at the check point, m 3 / s or kg / s.

[0181] For velocity flowmeters with pulse output signals:

[0182]

[0183] Where: f i —Select the standard frequency signal output by the standard signal source at the test point, 1 / s;

[0184] K—Flowmeter K coefficient (a fixed constant given after flowmeter calibration, obtained by the diagnostic module by reading the integrator), 1 / L or 1 / m 3 .

[0185] For differential pressure flowmeter:

[0186]

[0187] In the formula: C—outflow coefficient;

[0188] β—Ratio of the throttling device opening diameter to the upstream pipe inner diameter under operating conditions, β=d / D;

[0189] ε—expansion coefficient;

[0190] d—diameter of the throttle hole or throat of the throttle under working conditions, mm;

[0191] Δp i —Select the standard differential pressure output by the standard signal source at the inspection point, Pa;

[0192] ρ—Natural gas density under working conditions, kg / m 3 .

[0193] Except for the differential pressure, all other parameters on the right side of the equal sign in the formula are obtained by reading the integrator from the diagnostic module.

[0194] Specifically, the calculation method of the cumulative flow indication error of the integrator is as follows:

[0195] (1) When the integrator is in the designed working state, calibrate the points within the flow range (specified flow points can also be set according to user requirements).

[0196] (2) According to the selected inspection point, the standard signal source outputs the flow signal (the velocity flow meter is the frequency signal f i , differential pressure flowmeter is differential pressure signal Δp i), the integrator receives the signal. After the signal stabilizes, the timing starts. The calibration module reads the time t (t≥10min). The integrator displays the working condition cumulative flow Q within the time i ;

[0197] (3) The calibration module calculates the cumulative flow indication error E of the working condition within time t according to the following formula Q (The error should meet the maximum allowable error requirements of the corresponding accuracy level). If the error E Q If the error exceeds the allowable range, an early warning will be issued.

[0198]

[0199] Where: Q i —The totalizer displays the cumulative flow rate of the working condition within t time, m 3 or kg;

[0200] Q si —Theoretical cumulative flow rate m within time t calculated by the calibration module 3 or kg.

[0201] For velocity flowmeters with pulse output signals:

[0202]

[0203] Where: N—the number of frequency pulses output by the time standard signal source (the uncertainty introduced by the pulse resolution should be better than 1 / 10 of the maximum allowable error).

[0204] For differential pressure flowmeter:

[0205]

[0206] Specifically, the calculation method of the accumulated energy indication error of the integrator is as follows:

[0207] If the flow totalizer has the function of displaying the accumulated energy, the calibration module can calibrate the accumulated energy (the method is the same as the accumulated flow) in combination with the calorific value of the gas under the designed working condition. w Calculate as follows:

[0208]

[0209] Where: W i —Integrator displays accumulated energy, MJ or kWh;

[0210] W si —The calibration module calculates the theoretical cumulative flow rate, MJ or kWh (according to the method specified in GB / T 11062).

[0211] Specifically, the calculation method of the compensation parameter display error of the integrator is as follows:

[0212] (1) The experimental point is zero point and 0.25A max , 0.5A max , 0.75A max 、A max ;

[0213] (2) According to the selected inspection point, the standard signal source outputs the pressure or temperature signal, and the integrator receives the signal and measures and displays it;

[0214] (3) Calculate the error E of the selected inspection point according to the following formula Ai (The error should meet the maximum allowable error requirements of the corresponding accuracy level). If the error exceeds the allowable error range, an early warning will be prompted;

[0215]

[0216] Where: A i —Integrator indication, Pa or °C;

[0217] A si —Select the theoretical calculated value corresponding to the output signal of the standard signal source at the inspection point, Pa or °C;

[0218] A max —The theoretically calculated maximum value corresponding to the output signal of the standard signal source, in Pa or °C.

[0219] For temperature signal A max Take the upper temperature limit of the design task book.

[0220]

[0221] In the formula: C—outflow coefficient;

[0222] β—Ratio of the throttling device opening diameter to the upstream pipe inner diameter under operating conditions, β=d / D;

[0223] ε—expansion coefficient;

[0224] d—diameter of the throttle hole or throat of the throttle under working conditions, mm;

[0225] Δp i —Select the standard differential pressure output by the standard signal source at the inspection point, Pa;

[0226] ρ—Natural gas density under working conditions, kg / m 3 .

[0227] Except for the differential pressure, all other parameters on the right side of the equal sign in the formula are obtained by reading the integrator from the diagnostic module.

[0228] Although the present invention has been described above with reference to the exemplary embodiments and the accompanying drawings, it will be apparent to those skilled in the art that various modifications may be made to the above embodiments without departing from the spirit and scope of the claims.

Claims

1. A natural gas flow meter remote control method, characterized in that: The following steps are involved: S1 remote database server controls the digital diagnosis module to switch the function to the diagnosis state; S2 digital diagnostic module reads the static and dynamic parameters of the flow meter; The S3 digital diagnostic module combines the static and dynamic parameters it reads, calculates the theoretical flow rate through the diagnostic module's processor, and verifies the flow rate displayed by the flowmeter. In step S2, the static parameter diagnosis includes: S2-1 Temperament Component Diagnosis: S2-2 flowmeter structural parameter coefficient diagnosis; S2-3 flow range diagnosis; The above-mentioned S2-1 temperament component diagnosis includes: S2-1-1 static parameter module obtains the effective gas quality components of natural gas with the same gas source, and uploads them to the database server or writes the effective gas quality components through the database server; The S2-1-2 static parameter module reads the gas composition in the flow meter and uploads it to the database service. The database server calculates whether the molar composition is normalized, the natural gas compressibility factor, density and high-volume calorific value, and stores them; The database server in step S2-1-3 determines whether the gas composition of the flow meter is consistent with the effective gas composition. If so, the process proceeds to step S2-1-5; if not, the process proceeds to step S2-1-4. S2-1-4 database server alarm, after verification, authorization and confirmation, the gas composition of the flow meter can be remotely modified to be consistent through the database server; The database server in S2-1-5 monitors whether the modification interval of the gas composition of the flow meter exceeds the set period; if it exceeds, an alarm is issued, and after verification and authorization, the gas composition in the flow meter is diagnosed; S2-1-6 The database server automatically saves the first read or modification time as the start time of this cycle; The above-mentioned S2-2 flowmeter structural parameter diagnosis steps include: S2-2-1 static parameter module reads the flow meter K coefficient and segmented flow error value, uploads them to the database server or writes the verified effective flow meter K coefficient into the database server as a standard parameter for storage, and records the reading time as the start time of the effective period; The S2-2-2 static parameter module reads the real-time flow meter K coefficient once a day and uploads it to the database server to determine whether the K coefficient is consistent with the standard parameter. If it is inconsistent, an alarm will be issued; after verification, authorization, and confirmation, the gas composition in the flow meter can be remotely modified through the database server; The database server in S2-2-3 monitors whether the K-factor operation cycle of the flowmeter exceeds the verification cycle: prompts the flowmeter that is about to expire; and alarms the flowmeter that has exceeded the verification cycle time; S2-2-4 The database server also saves the most recently modified K coefficient as a new standard parameter for the next cycle diagnosis; The above S2-3 flow range diagnosis includes: S2-3-1 static parameter module reads the flow meter flow range and uploads it to the database server or enters the flow range through the database server; The database server described in S2-3-2 monitors the real-time flow rate daily; when the low-limit flow rate is lower than the lower limit setting value of the flow range, the low-limit operation time point and the accumulated time are recorded and an alarm is issued; when the high-limit flow rate is higher than the upper limit setting value of the flow range, the ultra-high limit operation time point and the accumulated time are recorded and an alarm is issued; The database server described in S2-3-3 automatically generates a monthly dynamic report on over-limit flow operation based on the over-limit operation time point and cumulative time, and adjusts the applicable status of the flow meter when necessary to reduce the measurement loss caused by the negative deviation caused by over-limit operation and over-limit operation; In step S2, dynamic parameter diagnosis includes: The S2-4-1 flow meter collects flow pressure, temperature, output pulse, and instantaneous flow under standard conditions in real time; The S2-4-2 dynamic parameter diagnosis module continuously reads the flow meter output pressure, temperature, output pulse, and instantaneous flow under standard conditions, and uploads them to the database server; The S2-4-2 database server selects the monitored parameters, such as pressure, temperature, output pulse, and instantaneous flow under standard conditions, sets a date range, and uses the recursive average filter algorithm model and the regional limit evaluation method to calculate the upper and lower limits of the parameters to generate a dynamic trend operating range within the date range. This allows for real-time monitoring of the production status and provides an alarm when an abnormality occurs. The step S3 specifically includes the following steps: The diagnostic module's processor calculates the theoretical flow rate and verifies the flow rate displayed by the flowmeter; including: S3-1 dynamic parameter interrupt module reads the real-time output pulse, pressure, and temperature of the flow meter, and combines the static parameter effective flow meter K coefficient obtained in step S2-2-1 and the effective gas quality components obtained in step S2-1-1, and the central processing unit calculates the theoretical standard instantaneous flow rate of natural gas; The S3-2 digital diagnostic module reads the instantaneous flow rate displayed by the flow meter under standard conditions; The central processing unit of the S3-3 digital diagnostic module compares the theoretical instantaneous flow rate under standard conditions with the instantaneous flow rate under standard conditions displayed by the flow meter. The digital diagnostic module uploads the comparison results to the database server; if the error exceeds the maximum allowable error, an alarm is issued; Specifically, the calculation method of instantaneous flow under theoretical standard conditions is as follows: Where: q n —Theoretical instantaneous volume flow rate calculated by the server under standard conditions, m 3 / s; q g —Theoretical instantaneous volume flow calculated by the server in working state, m 3 / s; P g —Absolute pressure of natural gas in working state collected by flowmeter, kPa; P n —Standard atmospheric pressure, 101.325 kPa; T n — Absolute temperature under standard conditions, 293.15K or 273.15K; T g —Absolute temperature of natural gas in working state collected by flow meter, K; Z n —Compression coefficient of natural gas under standard conditions; Z g —Compression coefficient of natural gas under working conditions.

2. A natural gas flow meter remote control method, characterized in that: The following steps are involved: The S4 remote database server controls the digital diagnostic module to switch the function to the calibration state; The S5 standard signal source outputs standard signals to the flowmeter, including standard current, voltage, frequency, pulse, and digital signals; The S6 flow meter receives the signal to display the corresponding flow rate and outputs the corresponding signal to the diagnostic module; The S7 diagnostic module reads the flow meter output signal, and the central processing unit calculates the flow meter indication error; The calculation method of the instantaneous flow indication error of S7-1 flowmeter is as follows: When the S7-1-1 flowmeter is in working condition, set the compensation pressure and temperature, and select inspection points near the lower limit of the flow range of the flow sensor, 0.25 times, 0.5 times, 0.75 times, and 1 times the maximum instantaneous flow rate; In addition, when the pressure is constant and the temperature is within the flow range, any two test points are selected, and the flow rate is the maximum; when the temperature is constant and the pressure is within the design range, any two test points are selected, and the flow rate is the maximum; Calibrate separately; S7-1-2 presses the selected inspection point, the standard signal source outputs flow, pressure and temperature signals simultaneously, the flow meter measures the signal and displays the instantaneous flow value; The S7-1-3 calibration module calculates the error E of each check point according to the following formula i , if the error E i If the error exceeds the allowable range, an alarm will be issued; Where: q i —Select the flow meter at the inspection point to display the instantaneous flow value, m 3 / s or kg / s; q si —Select the theoretical instantaneous flow value calculated by the calibration module at the check point, m 3 / s or kg / s; For velocity flowmeters with pulse output signals: Where: f i —Select the standard frequency signal output by the standard signal source at the test point, 1 / s; K—Flow meter K coefficient, 1 / L or 1 / m 3 ; For differential pressure flowmeter: In the formula: C—outflow coefficient; β—Ratio of the throttling device opening diameter to the upstream pipe inner diameter under working conditions, β=d / D; ε—expansion coefficient; d—opening diameter of the throttle under working conditions, mm; Δp i —Select the standard differential pressure output by the standard signal source at the inspection point, Pa; ρ—Natural gas density under working conditions, kg / m 3 ; Except for the differential pressure, all other parameters on the right side of the equal sign in the formula are obtained by reading the flow meter by the diagnostic module; The calculation method of the S7-2 flowmeter cumulative flow indication error is as follows: S7-2-1 flow meter calibration point within the flow range; S7-2-2 presses the selected inspection point, the standard signal source outputs the flow signal, and the flow meter receives the signal; after the signal stabilizes, the timing starts, and the calibration module reads the time t within which the flow meter displays the cumulative flow Q under the working condition i ; The S7-2-3 calibration module calculates the error E of the cumulative flow indication under working conditions within time t according to the following formula Q , if the error E Q If the error exceeds the allowable range, an alarm will be issued; Where: Q i —The flow meter displays the cumulative flow rate during the working condition within t time, m 3 or kg; Q si —Theoretical cumulative flow rate m within time t calculated by the calibration module 3 or kg; For velocity flowmeters with pulse output signals: Where: N—t is the number of frequency pulses output by the time standard signal source. The uncertainty introduced by the pulse resolution should be better than 1 / 10 of the maximum allowable error. For differential pressure flowmeter: The calculation method of the S7-3 flowmeter cumulative energy indication error is as follows: S7-3-1 Calibration of cumulative energy error E w Calculate as follows: Where: W i —The flow meter displays the accumulated energy, MJ or kWh; W si —The calibration module calculates the theoretical cumulative flow rate, MJ or kWh, according to the method specified in GB / T 11062; The calculation method of the compensation parameter display error of the S7-4 flowmeter is as follows: S7-4-1 experimental point is zero point, 0.25A max , 0.5A max , 0.75A max 、A max ; S7-4-2 presses the selected inspection point, the standard signal source outputs the pressure or temperature signal, the flow meter receives the signal and measures and displays it; S7-4-3 Calculate the error E of the selected inspection point according to the following formula Ai , the error should meet the maximum allowable error requirements of the corresponding accuracy level. If the error exceeds the allowable error range, an early warning will be prompted; Where: A i —Flow meter indication, Pa or °C; A si —Select the theoretical calculated value corresponding to the output signal of the standard signal source at the inspection point, Pa or °C; A max —The theoretically calculated maximum value corresponding to the output signal of the standard signal source, Pa or °C; For temperature signal A max Take the upper temperature limit of the design task book.

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