Flow calibration device and calibration method applicable to liquid single phase and gas-liquid two phase

Abstract

A flow calibration device and calibration method suitable for liquid single phase and gas-liquid two-phase, the device includes a liquid phase branch, a gas phase branch and a measurement main circuit, the liquid phase branch includes a liquid storage unit, a first front-end valve, a water pump, a standard liquid flow meter and a first rear-end valve connected in sequence; the gas phase main circuit includes a second front-end valve, a pressure acquisition unit, a temperature acquisition unit, a standard gas flow meter and a second rear-end valve connected in sequence; the measurement main circuit includes a mixer, a measurement pipeline, a phase content measurement module and a scale connected in sequence; the first rear-end valve and the second rear-end valve are connected to the front end of the mixer, and the rear end of the mixer is connected to the measurement pipeline, and the measurement pipeline is used to install the flow meter to be tested. This flow calibration device can not only realize the calibration of the standard liquid flow meter, but also realize the calibration of the flow meter of the gas-liquid two-phase flow, and will not interfere with the gas-liquid two-phase flow during the measurement process, thereby improving the accuracy of the detection result.

Description

Technical Field

[0001] The invention belongs to the technical field of flow meter calibration, and in particular relates to a flow calibration device and a calibration method suitable for liquid single phase and gas-liquid two phase. Background Art

[0002] Flow calibration is an important measurement work to ensure the uniformity, accuracy and reliability of the measurement value. The calibration device is crucial for the traceability of the measurement value and the stability of the flow meter performance.

[0003] With the increase in the use of biological, pharmaceutical, chemical and other occasions, not only the calibration work of traditional standard liquid flow meters has increased, but also the calibration demand for gas-liquid two-phase flow meters has increased.

[0004] At present, most of the calibration devices are single-phase, and the flowmeter is calibrated with single-phase liquid. For the calibration of two-phase, such as gas-liquid two-phase flow, due to the complexity of the device and the long calibration time, it is not widely used at present.

[0005] The above problems have brought many difficulties to the calibration of flow meters and also increased enterprise costs.

[0006] In order to solve the above problems and realize the calibration of gas-liquid two-phase flow, there are invasive calibration devices recorded in the prior art. However, such devices not only have complicated calibration processes, but also disturb the flow field distribution.

[0007] With the development of image processing technology, many multiphase flow measurement technologies implemented using high-speed cameras, nuclear magnetic resonance, ERT and other technologies are not only costly in use, but also not applicable in some occasions, and the size of such devices is also very large.

[0008] In summary, there is an urgent need for a flow meter calibration device and method with a simple structure and fast calibration speed, which can realize flow calibration and measurement of related parameters without interfering with the existing flow. Summary of the invention

[0009] The present invention aims to provide a flow calibration device and a calibration method which are simple in structure and good in use effect and are applicable to liquid single phase and gas-liquid two phase.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions: a flow calibration device suitable for liquid single phase and gas-liquid two phases, comprising a liquid phase branch, a gas phase branch and a measurement main circuit, wherein the liquid phase branch comprises a liquid storage unit, a first front-end valve, a water pump, a standard liquid flow meter and a first rear-end valve connected in sequence; the gas phase main circuit comprises a gas storage unit, a second front-end valve, a pressure acquisition unit, a temperature acquisition unit, a standard gas flow meter and a second rear-end valve connected in sequence; the measurement main circuit comprises a mixer, a measurement pipeline, a phase content measurement module and a scale connected in sequence; the first rear-end valve and the second rear-end valve are connected to the front end of the mixer, the rear end of the mixer is connected to the measurement pipeline, and the measurement pipeline is used to install the flow meter to be tested. The phase content measurement module comprises a data acquisition unit and a data processing unit, and the data acquisition unit acquires data and transmits the acquired data to the data processing unit.

[0011] The data acquisition unit includes a transparent pipe, a pair of laser diodes are arranged on the inner wall of the transparent pipe, and a light shielding cover is arranged on the outer side of the transparent pipe; among the paired laser diodes, one is a transmitting end and the other is a receiving end, and the receiving end transmits the collected data to the data processing unit.

[0012] The data processing unit includes a V / F conversion module, an amplification module and a control module; the data acquisition unit transmits the collected information to the V / F conversion module, the signal output end of the V / F conversion module is connected to the amplification module, and the amplification module transmits the received information to the control module.

[0013] The amplifier includes a low-noise operational amplifier and an instrument amplifier. The signal output end of the V / F conversion module is connected to the in-phase input end of the low-noise operational amplifier, the output end of the low-noise operational amplifier is connected to the instrument amplifier, and the output end of the instrument amplifier is connected to the signal input end of the control module.

[0014] The data acquisition unit also includes an excitation module, and the receiving end is connected to the excitation module. The excitation module includes a first photodiode, a second photodiode, a first compensation capacitor, a second compensation capacitor, a feedback resistor, a first transport amplifier, a first resistor and a first filter capacitor; the positive electrodes of the first photodiode and the second photodiode are grounded, and the negative electrodes of the first photodiode and the second photodiode are connected to the inverting input terminal of the first operational amplifier. The inverting input terminal of the first operational amplifier is also connected to the output terminal of the first operational amplifier through the first compensation capacitor, and the output terminal of the first operational amplifier is connected to the first end of the first resistor, and the second end of the first resistor is the output terminal; the second end of the first resistor is grounded through the first filter capacitor; the inverting input terminal of the first transport amplifier is connected to the second end of the first resistor through the second compensation capacitor and the feedback resistor connected in parallel, and the non-inverting input terminal of the first transport amplifier is grounded.

[0015] The method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument using the above-mentioned device comprises the following steps in sequence: (1) determining whether the flow meter under test is gas-liquid two-phase or single liquid phase, and if it is single liquid phase, proceeding to step (2); if it is gas-liquid two-phase, proceeding to step (5); (2) keeping the liquid phase branch in an unobstructed state and the gas phase branch in a closed state, and the liquid flows through the standard flow meter, the flow meter under test, and the phase content measurement module in sequence; (3) reading the data on the standard flow meter and the flow meter under test respectively, and subtracting the data of the flow meter under test from that of the standard flow meter to obtain the error of the flow meter under test; (4) repeating steps (2) and (3) to obtain multiple groups of data of the flow meter under test, namely A1, A2, ..., A n ; Find A1, A2, ... A n Average value A; calculate the uncertainty according to formula (1);

[0016] U A =max{ / A-Ai / , i=1, 2...n} Formula (1)

[0017] (5) Keep the gas phase branch and the liquid phase branch in an unobstructed state. The gas and liquid flow through the standard gas flowmeter and the standard liquid flowmeter respectively and then mix together. The mixed gas-liquid two-phase flow first enters the flowmeter to be tested to obtain the measured total flow signal, and then measure the measured phase content value of the gas-liquid two-phase flow; finally, measure the standard total flow signal of the gas-liquid two-phase flow (6) to calculate the standard phase content of the gas-liquid two-phase flow; (7) Difference between the measured phase content value and the standard phase content is calculated to obtain the error of the phase content measurement; According to the difference between the measured total flow and the standard total flow, the error of the gas-liquid two-phase flow meter to be measured is calculated; (8) Repeat steps (5) and (6) to obtain multiple sets of data on standard total flow, measured total flow, standard phase content and measured phase content, and calculate the uncertainty. The method for calculating the measured phase content value of the gas-liquid two-phase flow in step (5) is as follows: step (1) identifying the flow pattern of the gas-liquid two-phase flow; step (2) extracting the frequency of the flow pattern; step (3) constructing a phase content model, such as formula (3):

[0018] α L =αH+b+e Formula (3)

[0019] α L is the phase content of the liquid phase; H is the dimensionless frequency signal; α and b are unknown parameters; e is the residual;

[0020] Step (4) Set n fitting points to obtain formula (4)

[0021]

[0022] make

[0023]

[0024] Formula (5) is obtained

[0025] Y=Aθ+E Formula (5)

[0026] Step (5) fits the target and obtains formula (6):

[0027]

[0028] According to formula (6), the unknown parameters α and b are obtained;

[0029] Step (6) Given a residual data, the phase content α of the liquid phase is obtained according to the frequency signal of step (2) and the unknown parameters α and b obtained in step (5). L .

[0030] The method for obtaining the standard phase content of the gas-liquid two-phase flow in step (6) is:

[0031] The gas phase holdup is calculated by formula (2):

[0032]

[0033] Among them, α g is the gas phase holdup; Q L is the liquid volume flow rate; Q g is the gas phase volume flow rate; T b is the ambient temperature; P g is the environmental pressure; T L is the water phase temperature.

[0034] The gas-liquid two-phase flow enters the scale to measure the total flow rate of the gas-liquid two-phase flow.

[0035] Through the above technical scheme, the beneficial effects of the present invention are as follows: the flow calibration device can not only realize the calibration of the standard liquid flow meter, but also realize the calibration of the gas-liquid two-phase flow meter, and will not interfere with the gas-liquid two-phase flow during the measurement process, thereby improving the accuracy of the detection result. At the same time, the device has a simple structure, convenient operation and low energy consumption.

[0036] The principle of different transmission speeds of laser diodes in bubbles and water is used in the calibration of gas-liquid two-phase flow, which can not only measure the phase content but also realize image reconstruction.

[0037] This calibration method is simple and uses a laser diode to measure the phase holdup without interfering with the liquid. At the same time, the constructed model can be used to measure the standard phase holdup and the measured phase holdup value. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the connection of the device of the present invention;

[0039] Figure 2 It is a structural schematic diagram of the phase content measurement module;

[0040] Figure 3 It is a schematic diagram of the transparent pipeline structure;

[0041] Figure 4 This is the circuit schematic diagram of the excitation module;

[0042] Figure 5 is a flow chart of the method of the present invention;

[0043] Figure 6 It is the model diagram of the bubbly flow voltage signal;

[0044] Figure 7 It is the voltage-time signal diagram of bubbly flow;

[0045] Figure 8 is the model diagram of the slug flow voltage signal;

[0046] Fig. 9 is the slug flow voltage-time signal diagram;

[0047] Fig.10 It is the model diagram of laminar voltage signal;

[0048] Fig.11 is the laminar voltage-time signal diagram;

[0049] Fig.12 It is the model diagram of the annular flow voltage signal;

[0050] Fig.13 This is the annular current voltage-time signal diagram. DETAILED DESCRIPTION

[0051] Applicable to flow calibration devices for liquid single phase and gas-liquid two phase, such as Figures 1 to 4 As shown, it includes a liquid phase branch, a gas phase branch and a measurement main path. The liquid phase branch is used to circulate single-phase liquid, and the gas phase branch is used to circulate single-phase gas. The ends of the liquid phase branch and the gas phase branch are both connected to the measurement main path. When implemented, the liquid phase branch can be opened alone to allow the liquid to flow into the measurement main path, or the gas phase branch and the liquid phase branch can be opened at the same time, so that the liquid and gas are collected together in the measurement main path. The single-phase liquid or gas-liquid two-phase flow is measured and calibrated together in the measurement main path for related parameters.

[0052] The liquid phase branch includes a liquid storage unit 8, a first valve, a water pump 7, and a standard liquid flow meter 6 connected in sequence; the liquid storage unit 8 can be a water tank, the outlet of the water tank is connected to the water pump 7 through a pipeline, and the first rear end valve 131 is installed on the pipeline connecting the water tank and the water pump 7; the outlet of the water pump 7 is connected to the pipeline, and the standard liquid flow meter 6 and the first rear end valve are arranged on the pipeline. The standard liquid flow meter 6 is an approved liquid flow meter and can be used as a reference. The first valve includes a first front end valve 21 and a first rear end valve 131.

[0053] The gas phase main circuit includes a gas storage unit 1, a second valve, a pressure acquisition unit, a temperature acquisition unit, a standard gas flow meter 5 and a second rear end valve 132 connected in sequence; the gas storage unit 1 can be a nitrogen tank filled with nitrogen. The outlet of the nitrogen tank is connected to a pipeline, on which a second front end valve 22, a pressure acquisition unit, a temperature acquisition unit and a standard gas flow meter 5 are installed. The pressure acquisition unit and the temperature acquisition unit are respectively a pressure sensor 3 and a temperature sensor 4; the standard gas flow meter 5 is a standard standard gas flow meter 5. The second valve includes a second front end valve 22 and a second rear end valve 132.

[0054] The main measurement path includes a mixer 12, a measurement pipeline, a phase content measurement module 10 and a weighing device 11 connected in sequence; wherein the mixer 12 is used for mixing gas and liquid phases, the mixer 12 is a commercially available product, and this embodiment does not involve improvements to the mixer 12. The first rear end valve and the second rear end valve 132 are both connected to the front end of the mixer 12 through a pipeline.

[0055] The rear end of the phase mixer 12 is connected to a measuring pipeline for installing the flow meter 9 to be tested. The rear end of the measuring pipeline is connected to a phase content measurement module 10. The phase content measurement module 10 is connected to a pipeline, and a weighing device 11 is installed on the pipeline.

[0056] The reading of the flow meter 9 under test can be read out by measuring the flow meter on the pipeline, and then compared with the flow value read out by the standard flow meter to obtain the error of the flow meter 9 under test.

[0057] The phase content measurement module 10 includes a data acquisition unit and a data processing unit. The data acquisition unit acquires data and transmits the acquired data to the data processing unit.

[0058] The data acquisition unit includes a transparent pipe 14, on the inner wall of which are disposed four pairs of laser diodes 16, each pair of laser diodes 16 being used in pairs, one of the laser diodes being a transmitting end and the other being a receiving end. A light shielding cover 15 is provided outside the transparent pipe 14 to prevent the external environment from affecting the measurement results; the laser diode 16 as the receiving end transmits the collected data to the data processing unit.

[0059] The data acquisition unit also includes an excitation module. The laser diode 16 as the receiving end is connected to the excitation module. The excitation module includes a first photodiode D1, a second photodiode D2, a first compensation capacitor Cf1, a second compensation capacitor Cf2, a feedback resistor Rf, a first transport amplifier, a first resistor R and a first filter capacitor C.

[0060] The positive electrodes of the first photodiode D1 and the second photodiode D2 are grounded, and the negative electrodes of the first photodiode D1 and the second photodiode D2 are connected to the inverting input terminal of the first operational amplifier U1U1. The inverting input terminal of the first operational amplifier U1U1 is also connected to the output terminal of the first operational amplifier U1U1 through the first compensation capacitor Cf1. The output terminal of the first operational amplifier U1U1 is connected to the first end of the first resistor R, and the second end of the first resistor R is the output terminal; the second end of the first resistor R is grounded through the first filter capacitor C; the inverting input terminal of the first transport amplifier is connected to the second end of the first resistor R through the second compensation capacitor Cf2 and the feedback resistor Rf connected in parallel, and the non-inverting input terminal of the first transport amplifier is grounded.

[0061] The first compensation capacitor Cf1 is used to compensate for the phase lag caused by the filtering link, and the second compensation capacitor Cf2 is used to compensate for the phase lag caused by the input end of the low noise transport amplifier to control the noise gain peak.

[0062] The laser diode as the transmitting end emits light toward the opposite laser diode as the receiving end. When water flows through, when there is a gas phase, it will cause changes in the signal received by the receiving end. The receiving end transmits the received voltage signal to the data processing unit through the excitation module.

[0063] The optical signal of the laser diode 16 is converted into a voltage signal by the driving module.

[0064] The data processing unit includes a V / F conversion module and an amplification module; the data acquisition unit transmits the collected voltage information to the V / F conversion module, and the V / F conversion module converts the voltage signal into a frequency signal. The signal output end of the V / F conversion module is connected to the amplification module, and the amplification module amplifies the received frequency information and outputs it as a frequency signal.

[0065] The amplification module includes a low-noise operational amplifier (manufacturer: ADI, model: AD829) and an instrumentation amplifier (manufacturer: BB Company, model: INA103). The signal output end of the V / F conversion module is connected to the in-phase input end of the low-noise operational amplifier, the output end of the low-noise operational amplifier is connected to the in-phase input end of the instrumentation amplifier, and the output end of the instrumentation amplifier is connected to the frequency signal.

[0066] The optical signal of the laser diode 16 is converted into a voltage signal through the data processing unit. At the same time, the voltage signal is converted into a frequency signal, and then the frequency signal is amplified. The frequency signal of the gas-liquid two-phase flow flowing through the phase content measurement module 10 can be obtained. The user can obtain the error value of the flow meter 9 under different frequency signals.

[0067] The above device can not only realize the calibration of liquid flowmeter, but also realize the calibration of gas-liquid two-phase flowmeter. The device has a simple structure, convenient operation and low energy consumption. When calibrating the gas-liquid two-phase flowmeter, the principle of different transmission speeds of laser diode 16 in bubbles and water is adopted, which can not only realize the measurement of phase content but also realize image reconstruction.

[0068] The calibration method of liquid single-phase and gas-liquid two-phase measuring instruments using the above device is as follows: Figure 5 As shown, the method comprises the following steps in sequence:

[0069] (1) Determine whether the flow meter 9 under test is a two-phase gas-liquid flow or a single-phase flow. If it is a single-phase flow, proceed to step (2); if it is a two-phase gas-liquid flow, proceed to step (5);

[0070] (2) Keep the liquid phase branch in an unobstructed state and the gas phase branch in a closed state, and the liquid flows through the standard flow meter, the flow meter under test 9, and the phase content measurement module 10 in sequence;

[0071] (3) Read the data on the standard flow meter and the flow meter under test 9 respectively, and make a difference between the data of the flow meter under test 9 and the standard flow meter to obtain the error of the flow meter under test 9;

[0072] (4) Repeat steps (2) and (3) to obtain multiple sets of data of the flow meter 9 under test, namely A1, A2, ..., A n ; Find A1, A2, ... A n Average value A; calculate the uncertainty according to formula (1);

[0073] U A =max{ / A-Ai / , i=1, 2...n} Formula (1)

[0074] (5) Keep the gas phase branch and the liquid phase branch in an unobstructed state, read the flow rate of the liquid respectively; the flow rate, temperature and pressure of the gas, then the gas and liquid are mixed, and the mixed gas-liquid two-phase flow enters the flow meter 9 to be tested, and then the measured phase content value of the gas-liquid two-phase flow is measured; the method for obtaining the measured phase content value is:

[0075] Step (1) identifying the flow pattern of the gas-liquid two-phase flow;

[0076] 1) Establish flow pattern model in advance;

[0077] Among them, the flow type models are: bubbly flow, slug flow, laminar flow and annular flow.

[0078] The model diagrams of the voltage signals for bubbly flow, slug flow, laminar flow, and annular flow are shown in Figure 1. Figures 6 to 12 shown.

[0079] The spectrum characteristics of different flow types are shown in the following table:

[0080] Flow pattern Frequency distribution area Frequency main peak area bubble flow 0~150Hz 0~30Hz Slug flow 0~30Hz 0~10Hz Laminar Flow 0~100Hz 0~25Hz Annular Flow 0~500Hz 0~50Hz

[0081] 2) Identify the flow pattern of the gas-liquid two-phase flow; the identification method is: turn on four pairs of laser diodes in sequence, collect the frequency signals output by the data processing unit, obtain the frequency of the gas-liquid two-phase flow, integrate the signals collected by the four pairs of laser diodes, observe the frequency range, and determine the flow pattern of the gas-liquid two-phase flow according to the frequency range and the spectrum characteristic table of different flow rates.

[0082] The determination method is: first, find the corresponding flow type according to the frequency distribution area in the frequency range comparison table; then, finally determine the flow type according to the frequency main peak area in the frequency main peak comparison table. If it cannot be determined at one time, collect more frequency values ​​until the flow type can be determined.

[0083] If homogeneous flow and annular flow or homogeneous flow and laminar flow appear alternately periodically within the set time, the current flow pattern in the pipeline is judged as slug flow.

[0084] Step (2) extracting the frequency of the flow pattern;

[0085] Step (3) = construct a phase content model, such as formula (3):

[0086] α L =αH+b+e Formula (3)

[0087] α L is the phase content of the liquid phase; H is the dimensionless frequency signal; α and b are unknown parameters; e is the residual;

[0088] Step (4) Set n fitting points to obtain formula (4)

[0089]

[0090] make

[0091]

[0092] At the same time (5)

[0093] Y=Aθ+E Formula (5)

[0094] Step (5) fits the target and obtains formula (6):

[0095]

[0096] According to formula (6), the unknown parameters α and b are obtained;

[0097] Step (506) is to give a residual data, and obtain the phase content α of the liquid phase according to the frequency signal of step (502) and the unknown parameters α and b obtained in step (505). L .

[0098] The method for obtaining the standard phase content of the gas-liquid two-phase flow in step (6) is:

[0099] The gas phase holdup is calculated by formula (2):

[0100]

[0101] Among them, α g is the gas phase holdup; Q L is the liquid volume flow rate; Q g is the gas phase volume flow rate; T b is the ambient temperature; P g is the environmental pressure; T L is the water phase temperature.

[0102] The ambient temperature and the water phase temperature can be measured by a thermometer, the ambient pressure can be measured by a barometer, the water phase volume flow rate can be measured by a standard liquid flow meter, and the gas phase volume flow rate can be measured by a standard gas flow meter.

[0103] (7) Subtracting the measured phase content value from the standard phase content value to obtain the error; obtaining the total flow rate based on the measured phase content value and the liquid flow rate measured by the standard liquid flow meter; subtracting the total flow rate from the flow value measured by the measured flow meter to obtain the error of the measured flow meter;

[0104] (8) Repeat steps (5) and (6) to obtain multiple sets of data on the measured phase content values ​​and calculate the uncertainty.

[0105] (9) Give the calibration results: the error of the phase content measurement module and the error of the flow meter under different flow patterns.

[0106] The present invention provides a non-invasive calibration device and method, which can not only calibrate liquid flowmeters, but also calibrate gas-liquid two-phase flowmeters. The method can calibrate liquid single-phase flowmeters and gas-liquid two-phase flowmeters. At the same time, it can provide the flow pattern of the relevant gas-liquid two-phase flow, obtain the error of the detected signal under different meteors, and improve the calibration accuracy.

Claims

1. A method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument, characterized in that: The flow calibration device suitable for liquid single phase and gas-liquid two phase is used for the calibration. The flow calibration device includes a liquid phase branch, a gas phase branch and a measurement main path. The liquid phase branch includes a liquid storage unit, a first valve, a water pump and a standard liquid flow meter connected in sequence; the gas phase main path includes a gas tank, a second valve, a pressure acquisition unit, a temperature acquisition unit and a standard gas flow meter connected in sequence, wherein the gas tank is filled with nitrogen; the measurement main path includes a mixer, a measurement pipeline, a phase content measurement module and a scale connected in sequence; the first rear end valve and the second rear end valve are connected to the front end of the mixer, and the rear end of the mixer is connected to the measurement pipeline, and the measurement pipeline is used to install the flow meter to be tested; the phase content measurement module includes a data acquisition unit and a data processing unit, and the data acquisition unit collects data and transmits the collected data to the data processing unit; the data acquisition unit includes a transparent pipeline, and a pair of laser diodes are provided on the inner wall of the transparent pipeline, and a light shielding cover is provided on the outer side of the transparent pipeline; the pair of laser diodes, one of which is a transmitting end and the other is a receiving end, and the receiving end transmits the collected data to the data processing unit; The method comprises the following steps in sequence: (1) determining whether the flow meter under test is a two-phase gas-liquid flow meter or a single liquid phase, and if it is a single liquid phase, proceeding to step (2); if it is a two-phase gas-liquid flow meter, proceeding to step (5); (2) keeping the liquid phase branch in an unobstructed state and the gas phase branch in a closed state, and the liquid flows through the standard flow meter, the flow meter under test, and the phase content measurement module in sequence; (3) reading the data on the standard flow meter and the flow meter under test respectively, and performing a difference between the data of the flow meter under test and the standard flow meter to obtain the error of the flow meter under test; (4) repeating steps (2) and (3) to obtain multiple groups of data of the flow meter under test, namely A1, A2, ..., A n ; Find A1, A2, ... A n Average value A; calculate the uncertainty according to formula (1); U A =max{ / AA i / ,i=1,2……n} Formula (1) (5) Keep the gas phase branch and the liquid phase branch in an unobstructed state. The gas and liquid flow through the standard gas flowmeter and the standard liquid flowmeter respectively and then mix together. The mixed gas-liquid two-phase flow first enters the flowmeter to be tested to obtain the measured total flow signal, and then measure the measured phase content value of the gas-liquid two-phase flow; finally, measure the standard total flow signal of the gas-liquid two-phase flow; (6) Calculate the standard phase content of the gas-liquid two-phase flow; (7) Difference the measured phase content value with the standard phase content to obtain the error of the phase content measurement; According to the difference between the measured total flow and the standard total flow, the error of the gas-liquid two-phase flow meter to be tested is obtained; (8) Repeat steps (5) and (6) to obtain multiple sets of standard total flow, measured total flow, standard phase content and measured phase content data, and calculate the uncertainty; (9) Give the calibration results: the error of the phase content measurement module and the error of the flowmeter to be tested under different flow patterns; The method for calculating the measured phase content value of the gas-liquid two-phase flow in step (5) is as follows: step (501) identifying the flow pattern of the gas-liquid two-phase flow; step (502) extracting the frequency of the flow pattern; step (503) constructing a phase content model, such as formula (3): a L =αH+b+e formula (3) α L is the phase content of the liquid phase; H is the dimensionless frequency signal; α and b are unknown parameters; e is the residual; Step (504) sets n fitting points to obtain formula (4): make Formula (5) is obtained Y=Aθ+E Formula (5) Step (505) fits the target and obtains formula (6): According to formula (6), the unknown parameters α and b are obtained; Step (506) is to give a residual data, and obtain the phase content α of the liquid phase according to the frequency signal of step (502) and the unknown parameters α and b obtained in step (505). L .

2. The method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument as claimed in claim 1, characterized in that: The method for obtaining the standard phase content of the gas-liquid two-phase flow in step (6) is: The gas phase holdup is calculated by formula (2): Among them, α g is the gas phase holdup; Q L is the liquid volume flow rate; Q g is the gas phase volume flow rate; T b is the ambient temperature; P g is the environmental pressure; T L is the water phase temperature.

3. The method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument as claimed in claim 2, characterized in that: The gas-liquid two-phase flow enters the scale to measure the total flow rate of the gas-liquid two-phase flow.

4. The method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument as claimed in claim 3, characterized in that: The data processing unit includes a V / F conversion module and an amplification module; the data acquisition unit transmits the collected information to the V / F conversion module, the signal output end of the V / F conversion module is connected to the amplification module, and the amplification module outputs a frequency signal.

5. The method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument as claimed in claim 4, characterized in that: The amplifier includes a low-noise operational amplifier and an instrumentation amplifier. The signal output end of the V / F conversion module is connected to the in-phase input end of the low-noise operational amplifier, the output end of the low-noise operational amplifier is connected to the instrumentation amplifier, and the output end of the instrumentation amplifier is connected to the signal input end of the control module; the low-noise operational amplifier is produced by ADI and its model is AD829; the instrumentation amplifier is produced by BB and its model is INA103.

6. The method for calibrating a liquid single-phase and gas-liquid two-phase measuring instrument as claimed in claim 4, characterized in that: The data acquisition unit also includes an excitation module. The receiving end of the laser diode is connected to the excitation module. The excitation module includes a first photodiode, a second photodiode, a first compensation capacitor, a second compensation capacitor, a feedback resistor, a first transport amplifier, a first resistor and a first filter capacitor. The positive electrodes of the first photodiode and the second photodiode are grounded, and the negative electrodes of the first photodiode and the second photodiode are connected to the inverting input terminal of the first operational amplifier. The inverting input terminal of the first operational amplifier is also connected to the output terminal of the first operational amplifier through the first compensation capacitor. The output terminal of the first operational amplifier is connected to the first end of the first resistor, and the second end of the first resistor is the output terminal. The second end of the first resistor is grounded through the first filter capacitor. The inverting input terminal of the first transport amplifier is connected to the second end of the first resistor through the second compensation capacitor and the feedback resistor connected in parallel, and the non-inverting input terminal of the first transport amplifier is grounded.

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