Flow metering system and metering method used in middle and high pressure natural gas pipeline

Abstract

The invention discloses a flow metering system and metering method used in a middle-high pressure natural gas pipeline, and solves the problems that when natural gas in an existing natural gas conveying pipeline is metered, a user and a natural gas supplier cannot obtain accurate natural gas conveying data due to the situation that a pressure sensor breaks down or external signals are interrupted; and the problems of high power consumption and cost waste caused by continuous acquisition of pressure values by the pressure sensor are solved. By establishing the relationship between the signal amplitude and the pressure value, in the actual measurement process, the pressure value of the pipeline does not need to be continuously measured, and the gas flow in the natural gas pipeline can be obtained only by reversely deducing the pressure value according to the signal amplitude; and the gas pressure value in the current natural gas pipeline can be obtained under the condition that the built-in pressure sensor or external signal reading fails.

Description

Technical Field

[0001] The invention relates to a method for measuring medium flow in a natural gas pipeline, and in particular to a flow metering system and a metering method for medium- and high-pressure natural gas pipelines. Background Art

[0002] In the natural gas flow metering work applied to medium and high pressure occasions, pressure measurement is a very important metering parameter. Since natural gas has good compressibility, it is necessary to convert the working flow, that is, the flow of working pressure and temperature, into the standard flow during trade settlement. Therefore, it is crucial to obtain the real-time pressure in the medium and high pressure natural gas pipeline. In general, in the design of medium and high pressure natural gas pipeline flowmeters, the pressure in the pipeline is obtained by integrating the flowmeter with a pressure sensor or receiving an external signal.

[0003] The measurement steps of the traditional combined flow meter are:

[0004] 1. Use a flow meter to measure the flow rate of the medium, and obtain the flow rate per unit time through the cross-sectional area of ​​the pipeline, which is the working flow rate Fg;

[0005] 2. Then obtain the current medium pressure by sampling with a pressure sensor or communicating with the outside;

[0006] 3. Finally, the operating flow rate and the current medium are converted into the standard flow rate through the conversion formula, and this process is repeated every second.

[0007] The above method has the following risks:

[0008] 1. When the built-in pressure sensor in the pipeline fails or the external signal is interrupted, the flow meter will completely lose the pressure value acquisition and will not be able to calculate the conversion of operating flow to standard flow, which will cause business disputes between the user and the gas supplier.

[0009] 2. Ultrasonic or other electronic flow meters consume a lot of power when working. If the pressure value is measured every second in a continuous measurement cycle, it will cause additional power consumption and significantly reduce the standby time of battery-powered products. However, measuring once every multiple cycles cannot capture pressure changes in time.

[0010] 3. When measuring multi-channel flow meter products, continuous pressure measurement will take up more machine cycles, and the controller cannot enter the sleep state in time. If a higher frequency crystal oscillator is used to increase the working speed, it will cause additional power consumption and material costs. Summary of the invention

[0011] The purpose of the present invention is to solve the problem that when measuring natural gas in existing natural gas transmission pipelines, users and natural gas suppliers cannot obtain accurate natural gas transmission data due to pressure sensor failure or external signal interruption; and the pressure sensor continuously collects pressure values, resulting in high power consumption and cost waste, and to provide a flow metering system and metering method for medium and high pressure natural gas pipelines.

[0012] In order to achieve the above object, the present invention adopts the following technical solution:

[0013] A flow metering system for medium and high pressure natural gas pipelines, comprising: an electronic flow meter, a pressure sensor and a temperature sensor arranged in the natural gas pipeline; the particularity thereof is that it also comprises an amplification circuit, a signal processing chip, a waveform detection circuit and a flow meter main control chip; the waveform detection circuit is used to detect the magnitude of the signal amplitude affected by pressure changes;

[0014] The signal transmitting end of the electronic flow meter is used to transmit an electrical signal, and the signal receiving end of the electronic flow meter is used to receive the electrical signal transmitted by the signal transmitting end;

[0015] The amplification circuit includes a signal amplification circuit and a signal comparison circuit. The input end of the signal amplification circuit is communicatively connected to the signal receiving end of the electronic flow meter. The output end of the signal amplification circuit is connected to the signal comparison circuit. The output end of the signal comparison circuit is connected to the input end of the signal processing chip. The output end of the signal processing chip is connected to the main control chip of the flow meter. The signal processing chip is used to obtain the flight time of the electrical signal in the measured medium in the natural gas pipeline and output the result to the main control chip of the flow meter.

[0016] The input end of the waveform detection circuit is connected to the output end of the signal amplification circuit, and the output end is connected to the analog input end of the flow meter main control chip, which is used to collect the amplified signal of the signal amplification circuit to obtain the signal amplitude;

[0017] The pressure sensor and the temperature sensor are both connected to the flow meter main control chip, and the flow meter main controller chip controls the pressure sensor and the temperature sensor to measure the pressure value and temperature in the natural gas pipeline respectively according to the change of the signal amplitude;

[0018] The flow meter main control chip is used to calculate the working condition flow value of the measured medium in the pipeline according to the output result of the signal processing chip, and obtain the standard condition flow value in the natural gas pipeline in combination with the pressure value and temperature in the pipeline.

[0019] The waveform detection circuit includes a resistor R101, a resistor R102, a resistor R103, a resistor R104, a capacitor C101, a capacitor C102 and a diode D110;

[0020] One end of the resistor R101 is connected to the amplifier circuit, and the other end is respectively connected to the positive electrode of the diode D110, one end of the resistor R102, and the positive plate of the capacitor C101. The other end of the resistor R102 and the negative plate of the capacitor C101 are both grounded; the negative electrode of the diode D110 is respectively connected to one end of the resistor R104, the positive plate of the capacitor C102, and one end of the resistor R103. The negative plate of the capacitor C102 and the other end of the resistor R103 are both grounded. The other end of the resistor R104 is connected to the flow meter main control chip.

[0021] The present invention also provides a flow metering method for medium and high pressure natural gas pipelines, which is based on the flow metering system for medium and high pressure natural gas pipelines, and is special in that it includes the following steps:

[0022] S1. Connect the electronic flow meter, pressure sensor, and temperature sensor to the inner wall of the medium and high pressure natural gas pipeline, take T=1s as the measurement period, obtain the temperature in the pipeline, and the electrical signal emitted by the electronic flow meter, and input the electrical signal into the signal amplifier circuit for amplification. One path is input into the waveform detection circuit to obtain the signal amplitude, and the other path is calculated through the signal comparison circuit, signal processing chip, and flow meter main control chip to calculate the working flow F. g ;

[0023] S2. In the running program of the main control chip of the flow meter, the pressure value in the medium and high pressure natural gas pipeline is divided into M levels, the one-to-one correspondence between the pressure value in the natural gas pipeline and the signal amplitude in each level is determined, and a corresponding relationship model between the pressure value and the signal amplitude in each level is constructed;

[0024] S3, measure the pressure value of the high-pressure natural gas pipeline in the n-1th cycle as P n-1 And the signal amplitude W n-1 , where n≥2;

[0025] S4. Measure the signal amplitude W of the nth cycle n , the signal amplitude W n With the signal amplitude W n-1 Compare and obtain the ratio K;

[0026] S5. Set the ratio threshold interval (K1, K2). Combined with the relationship between the ratio K and the ratio threshold interval (K1, K2), the flow meter main control chip controls the pressure sensor, reads the external communication, and determines the signal amplitude W. n The pressure value P of the nth measurement cycle is obtained by the level n ;

[0027] S6. According to the pressure value P of the nth measurement cycle n , temperature, and operating flow rate, and calculate the standard flow rate in medium and high pressure natural gas pipelines.

[0028] Furthermore, the specific process of S2 is: the pressure value in the medium and high pressure natural gas pipeline is fully divided into M levels, the pressure value in the natural gas pipeline is sampled through the pressure sensor on the natural gas pipeline, and the sampling period is 1s. At the same time, the signal amplitude of the natural gas pipeline is obtained by the method of S1, and the pressure value and signal amplitude in the natural gas pipeline at the same time are saved one by one, and a corresponding relationship model between the pressure value and the signal amplitude in each level is constructed.

[0029] Further, in S2, the expression of the corresponding relationship model between the pressure value and the signal amplitude in each level is:

[0030]

[0031] Where P x+1 , P x , P k represent the pressure values ​​in the natural gas pipeline at the x+1th, xth, and kth cycles in the i-th level, respectively. x+1 , W x , W k They represent the signal amplitudes of the x+1th, xth, and kth cycles in the i-th level, respectively, where 1≤i≤M.

[0032] Furthermore, the specific process of S5 is as follows:

[0033] Set the ratio threshold interval (K1, K2) to determine whether K∈(K1, K2) is satisfied. If so, the pressure value of the high-pressure natural gas pipeline in the nth measurement cycle is P n =P n-1 Otherwise, determine whether the pressure sensor is faulty; if not, measure the pressure value P of the natural gas pipeline in the nth measurement cycle through the pressure sensor. n If there is a fault, it is determined whether the pressure of the nth measurement cycle in the natural gas pipeline can be determined by an external signal. If so, the pressure P of the nth measurement cycle in the natural gas pipeline is obtained by an external signal. n , otherwise, determine the signal amplitude W of the nth measurement cycle n The level interval in which it is located, and the pressure value P of the nth measurement period is inferred based on the level interval n .

[0034] Further, in S5, the signal amplitude W of the nth measurement cycle is determined n The level interval in which it is located, and the pressure value P of the nth measurement period is inferred based on the level interval n Specifically:

[0035] Determine the signal amplitude W of the nth measurement cycle nThe level is m, where 1≤m≤M; determine the signal amplitude W of the nth measurement cycle n The corresponding relationship model between the pressure value and the signal amplitude within the level;

[0036] Then we have:

[0037]

[0038] Among them, P x+1 , P x , P x represents the pressure value in the natural gas pipeline at the x+1th, xth, and nth cycles in the mth level, respectively. x+1 , W x , W k They represent the signal amplitudes of the x+1th, xth, and nth cycles in the mth level respectively.

[0039] Furthermore, S6 is specifically:

[0040] According to the pressure value P of the nth measurement cycle n , the temperature determines the compression factor C in the pipeline in the nth measurement cycle, and the compression factor C in the pipeline in the nth measurement cycle and the operating flow rate F in the nth measurement cycle are calculated. g , calculate the standard flow rate F of the nth measurement cycle in the medium and high pressure natural gas pipeline b , the calculation formula is:

[0041] F b =F g ×C.

[0042] Beneficial effects of the present invention:

[0043] 1. The present invention discloses a flow metering system for medium and high pressure natural gas pipelines. Based on an electronic flow meter, an amplifier circuit and a waveform detection circuit are connected to detect the signal amplitude of the attenuated natural gas electrical signal, so as to update the pressure value in the pipeline according to the change of the signal amplitude of the attenuated electrical signal, and then obtain the standard flow rate in combination with the pressure value, temperature and operating flow rate.

[0044] 2. The flow metering system for medium and high pressure natural gas pipelines of the present invention also has the advantages of simple structure and convenient operation.

[0045] 3. The present invention provides a flow metering method for medium and high pressure natural gas pipelines. By establishing a relationship between signal amplitude and pressure value, in the actual measurement process, there is no need to continuously measure the pipeline pressure value. The gas flow in the natural gas pipeline can be obtained by simply inferring the pressure value based on the signal amplitude. In the event that the built-in pressure sensor or external signal reading fails, the gas pressure value in the current natural gas pipeline can be obtained.

[0046] 4. The present invention provides a flow metering method for medium and high pressure natural gas pipelines, which can capture real-time pressure changes and update pressure values ​​without continuously measuring the natural gas pipeline pressure, and hardly increases power consumption and machine working cycle, thereby solving the problem of high power consumption and cost waste caused by the continuous use of pressure sensors to measure pressure.

[0047] 5. The present invention provides a flow metering method for medium and high pressure natural gas pipelines, which divides the standard pressure into M levels, and establishes a corresponding relationship between the standard pressure and the signal amplitude in each level, thereby improving the accuracy of the reverse pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a circuit diagram of an amplifier circuit used in an embodiment of a flow metering system for medium and high pressure natural gas pipelines of the present invention;

[0049] Figure 2 The invention is a waveform detection circuit and a flow metering system for medium and high pressure natural gas pipelines. Figure 1 Circuit diagram of the amplifier circuit;

[0050] Figure 3 It is a flow chart of an embodiment of a flow metering method for medium and high pressure natural gas pipelines of the present invention;

[0051] Figure 4 This is a graph showing the relationship between signal amplitude and pressure in an embodiment of a flow metering method for a medium- and high-pressure natural gas pipeline of the present invention. DETAILED DESCRIPTION

[0052] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] A flow metering system for medium and high pressure natural gas pipelines, comprising: an electronic flow meter, a pressure sensor, and a temperature sensor arranged in the natural gas pipeline; an amplification circuit, a signal processing chip, a waveform detection circuit, and a flow meter main control chip;

[0054] Among them, the amplifier circuit is as follows Figure 1As shown, it includes a signal amplification circuit and a signal comparison circuit. The input end of the signal amplification circuit is communicatively connected to the signal receiving end of the electronic flow meter, the output end of the signal amplification circuit is connected to the signal comparison circuit, the output end of the signal comparison circuit is connected to the input end of the signal processing chip, and the output end of the signal processing chip is connected to the flow meter main control chip. The signal processing chip is used to obtain the flight time of the electrical signal in the measured medium in the natural gas pipeline, and output the result to the flow meter main control chip; in this embodiment, it is necessary to calculate the standard flow rate by combining the operating flow rate with the pressure and temperature in the pipeline.

[0055] like Figure 2 As shown, the waveform detection circuit includes: one end of the resistor R101 is connected to the signal amplification circuit, and the other end is respectively connected to the positive electrode of the diode D110, one end of the resistor R102, and the positive plate of the capacitor C101, and the other end of the resistor R102 and the negative plate of the capacitor C101 are grounded; the negative electrode of the diode D110 is respectively connected to one end of the resistor R104, the positive plate of the capacitor C102, and one end of the resistor R103, and the negative plate of the capacitor C102 and the other end of the resistor R103 are grounded, and the other end of the resistor R104 is connected to the main control chip of the flow meter. In this embodiment, the waveform detection circuit is used for modulation analysis of high-frequency signals, and envelope detection is used to convert the sine wave into a waveform that can reflect its amplitude change.

[0056] In this embodiment, the connection relationship between the waveform detection circuit and the signal amplification circuit is as follows: Figure 2 As shown, the waveform detection circuit can collect the amplified signal of the signal amplification circuit and convert it into a signal amplitude. At the same time, the amplitude of the amplified signal is input into the signal comparison circuit for comparison processing, and the compared signal is input into the signal processing chip and the flow meter main control chip. The signal processing chip is used to obtain the flight time of the electrical signal in the measured medium in the natural gas pipeline, and output the result to the flow meter main control chip.

[0057] The pressure sensor and the temperature sensor are both connected to the flow meter main control chip. The flow meter main controller chip controls the pressure sensor and the temperature sensor to measure the pressure value and temperature in the natural gas pipeline respectively according to the change of the signal amplitude.

[0058] In this embodiment, the signal amplification circuit amplifies the electrical signal and inputs it into the signal comparison circuit and the waveform detection circuit at the same time. After the signal comparison circuit compares and processes the signal, the signal processing chip obtains the flight time of the electrical signal in the measured medium in the natural gas pipeline, and then inputs it into the flow meter main control chip to calculate the working condition flow rate. This process is input into the conventional usage method. However, in this embodiment, the amplitude of the amplified electrical signal is also required to be detected to obtain the amplitude of the amplified signal, and the amplitude of the amplified signal is input into the flow meter main control chip. The flow meter main control chip controls the pressure sensor and the temperature sensor to measure the pressure value and temperature in the natural gas pipeline according to the amplitude change of the amplified signal.

[0059] The flow meter main control chip is used to calculate the operating flow value of the measured medium in the pipeline according to the output results of the signal processing chip, and obtain the standard flow value in the natural gas pipeline in combination with the pressure value and temperature in the pipeline.

[0060] This embodiment also provides a flow measurement method for medium and high pressure natural gas pipelines, such as Figure 3 As shown, the following steps are included:

[0061] S1. Connect the electronic flow meter, pressure sensor, and temperature sensor to the inner wall of the medium and high pressure natural gas pipeline, take T=1s as the measurement period, obtain the temperature in the pipeline, and the electrical signal emitted by the electronic flow meter, and input the electrical signal into the signal amplifier circuit for amplification. One path is input into the waveform detection circuit to obtain the signal amplitude, and the other path is calculated through the signal comparison circuit, signal processing chip, and flow meter main control chip to calculate the working flow F. g ;

[0062] S2. The pressure values ​​in the medium and high pressure natural gas pipeline are fully divided into M levels. The pressure values ​​in the natural gas pipeline are sampled through the pressure sensor on the natural gas pipeline. The sampling period is 1s. At the same time, the signal amplitude of the natural gas pipeline is obtained by the method of S1. The pressure value and signal amplitude in the natural gas pipeline at the same time are saved one by one, and a corresponding relationship model between the pressure value and the signal amplitude in each level is constructed.

[0063] In this embodiment, in the electronic flow meter, the amplitude of the electrical signal will continue to attenuate when transmitted in a medium at a certain distance, that is, the received signal amplitude must be lower than the transmitted signal amplitude. The degree of signal attenuation is inversely proportional to the pressure of the medium, that is, as the pressure increases, the attenuation degree of the signal decreases during flight, causing the measured signal amplitude to increase. Conversely, as the pressure decreases, the attenuation degree of the signal increases during flight, causing the measured signal amplitude to decrease. Figure 4 shown.

[0064] from Figure 4It can be seen that when the flow meter measurement signal is under the same shock intensity and measurement working conditions, the change in pressure will definitely cause the signal amplitude to change, and this change is real-time and sensitive. As the gas pressure increases, the amplitude of the measured signal will also increase, showing a linear relationship. Utilizing this characteristic, this embodiment collects the signal amplitude and compares it with the signal amplitude of the previous cycle to determine whether the pressure has changed. When the signal amplitude changes by more than a certain set value, the system determines that the pressure has changed, and the system will re-measure the new pressure value. Update the current pressure value and store the current pressure value and the corresponding electrical signal amplitude. The measurement system will continuously store the new pressure value and the corresponding signal amplitude during operation. When the pressure sensor fails or cannot obtain the external pressure signal, the pressure can be reversed through the measurement result of the signal amplitude to avoid settlement disputes caused by the inability to measure the pressure value and improve system reliability.

[0065] The expression of the corresponding relationship model between the pressure value and the signal amplitude in each level is:

[0066]

[0067] Where P x+1 , P x , P k represent the pressure values ​​in the natural gas pipeline at the x+1th, xth, and kth cycles in the i-th level, respectively. x+1 , W x , W k They represent the signal amplitudes of the x+1th, xth, and kth cycles in the i-th level, respectively, where 1≤i≤M.

[0068] S3, measure the pressure value of the high-pressure natural gas pipeline in the n-1th cycle as P n-1 And the signal amplitude W n-1 , where n≥2;

[0069] S4. Measure the signal amplitude W of the nth cycle n , the signal amplitude W n With the signal amplitude W n-1 Compare and obtain the ratio K;

[0070] S5. Process Figure 3 As shown, the ratio threshold interval (K1, K2) is set to determine whether K∈(K1, K2) is satisfied. If so, the pressure value of the high-pressure natural gas pipeline in the nth measurement cycle is P n =P n-1 Otherwise, determine whether the pressure sensor is faulty; if not, measure the pressure value P of the natural gas pipeline in the nth measurement cycle through the pressure sensor. nIf there is a fault, it is determined whether the pressure of the nth measurement cycle in the natural gas pipeline can be determined by an external signal. If so, the pressure P of the nth measurement cycle in the natural gas pipeline is obtained by an external signal. n , otherwise, determine the signal amplitude W of the nth measurement cycle n The level interval in which it is located, and the pressure value P of the nth measurement period is inferred based on the level interval n Specifically:

[0071] Determine the signal amplitude W of the nth measurement cycle n The level is m, where 1≤m≤M; determine the signal amplitude W of the nth measurement cycle n The corresponding relationship model between the pressure value and the signal amplitude within the level;

[0072] Then we have:

[0073]

[0074] Among them, P x+1 , P x , P x represents the pressure value in the natural gas pipeline at the x+1th, xth, and nth cycles in the mth level, respectively. x+1 , W x , W k They represent the signal amplitudes of the x+1th, xth, and nth cycles in the mth level respectively.

[0075] S6. According to the pressure value P of the nth measurement cycle n , the temperature determines the compression factor C in the pipeline in the nth measurement cycle, and the compression factor C in the pipeline in the nth measurement cycle and the operating flow rate F in the nth measurement cycle are calculated. g , calculate the standard flow rate F of the nth measurement cycle in the medium and high pressure natural gas pipeline b , the calculation formula is:

[0076] F b =F g ×C.

[0077] In this embodiment, the compression factor coefficient is obtained by inputting the current working pressure and temperature values, which is a fixed algorithm in the national standard.

[0078] In this embodiment, a flow metering system for medium and high pressure natural gas pipelines is combined with a metering method. By establishing a relationship between signal amplitude and pressure value, in the actual measurement process, there is no need to continuously measure the pipeline pressure value. The pressure value can be inferred from the signal amplitude to obtain the gas flow in the natural gas pipeline. In the case of failure of the built-in pressure sensor or external signal reading, the gas pressure value in the current natural gas pipeline can be obtained. The flow metering method of the present invention can capture real-time pressure changes and update the pressure value without continuously measuring the natural gas pipeline pressure, and almost does not increase power consumption and machine working cycle, thereby solving the problem of high power consumption and cost waste caused by continuous use of pressure sensors to measure pressure.

[0079] The above description is only a specific embodiment of the present invention, and a comparison of the effects of the specific embodiments and the related comparative examples, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A flow metering system for medium and high pressure natural gas pipelines, comprising: An electronic flow meter, a pressure sensor, and a temperature sensor are arranged in a natural gas pipeline; the characteristics include: an amplification circuit, a signal processing chip, a waveform detection circuit, and a flow meter main control chip; The signal transmitting end of the electronic flow meter is used to transmit an electrical signal, and the signal receiving end of the electronic flow meter is used to receive the electrical signal transmitted by the signal transmitting end; The amplification circuit includes a signal amplification circuit and a signal comparison circuit. The input end of the signal amplification circuit is communicatively connected to the signal receiving end of the electronic flow meter. The output end of the signal amplification circuit is connected to the signal comparison circuit. The output end of the signal comparison circuit is connected to the input end of the signal processing chip. The output end of the signal processing chip is connected to the main control chip of the flow meter. The signal processing chip is used to obtain the flight time of the electrical signal in the measured medium in the natural gas pipeline and output the result to the main control chip of the flow meter. The input end of the waveform detection circuit is connected to the output end of the signal amplification circuit, and the output end is connected to the analog input end of the flow meter main control chip, which is used to collect the amplified signal of the signal amplification circuit to obtain the signal amplitude; The pressure sensor and the temperature sensor are both connected to the flow meter main control chip, and the flow meter main controller chip controls the pressure sensor and the temperature sensor to measure the pressure value and temperature in the natural gas pipeline respectively according to the change of the signal amplitude; The flow meter main control chip is used to calculate the working condition flow value of the measured medium in the pipeline according to the output result of the signal processing chip, and obtain the standard condition flow value in the natural gas pipeline in combination with the pressure value and temperature in the pipeline.

2. A flow metering system for medium and high pressure natural gas pipelines according to claim 1, characterized in that: The waveform detection circuit includes a resistor R101, a resistor R102, a resistor R103, a resistor R104, a capacitor C101, a capacitor C102 and a diode D110; One end of the resistor R101 is connected to the amplifier circuit, and the other end is respectively connected to the positive electrode of the diode D110, one end of the resistor R102, and the positive plate of the capacitor C101. The other end of the resistor R102 and the negative plate of the capacitor C101 are both grounded; the negative electrode of the diode D110 is respectively connected to one end of the resistor R104, the positive plate of the capacitor C102, and one end of the resistor R103. The negative plate of the capacitor C102 and the other end of the resistor R103 are both grounded. The other end of the resistor R104 is connected to the flow meter main control chip.

3. A flow metering method for medium and high pressure natural gas pipelines, using the flow metering system for medium and high pressure natural gas pipelines according to claim 1 or 2, characterized in that: The following steps are involved: S1. Connect the electronic flow meter, pressure sensor, and temperature sensor to the inner wall of the medium and high pressure natural gas pipeline, take T=1s as the measurement period, obtain the temperature in the pipeline, and the electrical signal emitted by the electronic flow meter, and input the electrical signal into the signal amplifier circuit for amplification. One path is input into the waveform detection circuit to obtain the signal amplitude, and the other path is calculated through the signal comparison circuit, signal processing chip, and flow meter main control chip to calculate the working flow F. g ; S2. In the running program of the main control chip of the flow meter, the pressure value in the medium and high pressure natural gas pipeline is divided into M levels, the one-to-one correspondence between the pressure value in the natural gas pipeline and the signal amplitude in each level is determined, and a corresponding relationship model between the pressure value and the signal amplitude in each level is constructed; S3, measure the pressure value of the high-pressure natural gas pipeline in the n-1th cycle as P n-1 And the signal amplitude W n-1 , where n≥2; S4. Measure the signal amplitude W of the nth cycle n , the signal amplitude W n With the signal amplitude W n-1 Compare and obtain the ratio K; S5. Set the ratio threshold interval (K1, K2). Combined with the relationship between the ratio K and the ratio threshold interval (K1, K2), the flow meter main control chip controls the pressure sensor, reads the external communication, and determines the signal amplitude W. n The pressure value P of the nth measurement cycle is obtained by n ; S6. According to the pressure value P of the nth measurement cycle n , temperature, and operating flow rate, and calculate the standard flow rate in medium and high pressure natural gas pipelines.

4. A flow measurement method for medium and high pressure natural gas pipeline according to claim 3, characterized in that: The specific process of S2 is: the pressure value in the medium and high pressure natural gas pipeline is fully divided into M levels, and the pressure value in the natural gas pipeline is sampled through the pressure sensor on the natural gas pipeline. The sampling period is 1s. At the same time, the signal amplitude of the natural gas pipeline is obtained by the method of S1. The pressure value and signal amplitude in the natural gas pipeline at the same time are saved one by one, and the corresponding relationship model between the pressure value and the signal amplitude in each level is constructed.

5. A flow measurement method for medium and high pressure natural gas pipeline according to claim 4, characterized in that: In S2, the expression of the corresponding relationship model between the pressure value and the signal amplitude in each level is: Where P x+1 , P x , P k represent the pressure values ​​in the natural gas pipeline at the x+1th, xth, and kth cycles in the i-th level, respectively. x+1 , W x , W k They represent the signal amplitudes of the x+1th, xth, and kth cycles in the i-th level, respectively, where 1≤i≤M.

6. A flow measurement method for medium and high pressure natural gas pipeline according to claim 5, characterized in that: The specific process of S5 is as follows: Set the ratio threshold interval (K1, K2) to determine whether K∈(K1, K2) is satisfied. If so, the pressure value of the high-pressure natural gas pipeline in the nth measurement cycle is P n =P n-1 Otherwise, determine whether the pressure sensor is faulty; if not, measure the pressure value P of the natural gas pipeline in the nth measurement cycle through the pressure sensor. n If there is a fault, it is determined whether the pressure of the nth measurement cycle in the natural gas pipeline can be determined by an external signal. If so, the pressure P of the nth measurement cycle in the natural gas pipeline is obtained by an external signal. n , otherwise, determine the signal amplitude W of the nth measurement cycle n The level interval in which it is located, and the pressure value P of the nth measurement period is inferred based on the level interval n .

7. A flow measurement method for medium and high pressure natural gas pipeline according to claim 6, characterized in that: In S5, the signal amplitude W of the nth measurement cycle is determined. n The level interval in which it is located, and the pressure value P of the nth measurement period is inferred based on the level interval n Specifically: Determine the signal amplitude W of the nth measurement cycle n The level is m, where 1≤m≤M; determine the signal amplitude W of the nth measurement cycle n The corresponding relationship model between the pressure value and the signal amplitude within the level; Then we have: Among them, P x+1 , P x , P x represents the pressure value in the natural gas pipeline at the x+1th, xth, and nth cycles in the mth level, respectively. x+1 , W x , W k They represent the signal amplitudes of the x+1th, xth, and nth cycles in the mth level respectively.

8. A flow measurement method for medium and high pressure natural gas pipeline according to claim 6, characterized in that: S6 is specifically: According to the pressure value P of the nth measurement cycle n , the temperature determines the compression factor C in the pipeline in the nth measurement cycle, and the compression factor C in the pipeline in the nth measurement cycle and the operating flow rate F in the nth measurement cycle are calculated based on the compression factor C in the pipeline in the nth measurement cycle. g , calculate the standard flow rate F of the nth measurement cycle in the medium and high pressure natural gas pipeline b , the calculation formula is: F b =F g ×C。

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