Gas-liquid two-phase flow measurement method based on elbow and acoustic emission technology

Abstract

This method for measuring the flow rate of gas-liquid two-phase flow based on pipe bend and acoustic emission technology belongs to the field of gas-liquid two-phase flow measurement. The method includes measuring the average liquid holdup of the two-phase flow within the pipe. H L Calculate the instantaneous velocity of the gas and liquid phases at the 45° section of the bend in the pipe. Vc ; Identify the gas-liquid two-phase flow pattern within the pipeline; Vc , H L Apparent fluid velocity V SL and apparent gas velocity V SG As variables, dimensional analysis is used to propose different flow patterns. Vc , H L and V SL , V SG The correlation formula; calculate the effective voltage value of the acoustic emission signal. RMS ,Establish RMS and V SL and V SG The correlation equation; the parameters in the fitted correlation equation; the newly acquired data as input to the fitted correlation equation. Vc , H L RMS, output V SL , V SG This allows for the measurement of the flow rate of the gas-liquid two-phase flow. Compared with the single-phase metering method commonly used in the oil and gas industry after separation, this invention has advantages such as simple structure, low measurement cost, real-time measurement capability, and non-invasiveness.

Description

TECHNICAL FIELD

[0001] The present application relates to a gas-liquid two-phase flow measurement method using a bend flowmeter combined with acoustic emission technology, and belongs to the field of gas-liquid two-phase flow measurement. BACKGROUND

[0002] In petroleum engineering, the wellhead produced fluid is mostly gas-liquid two-phase flow, and wellhead measurement is of great significance for production guidance. At present, with the further development of offshore oil and gas fields, the space of offshore oil and gas platforms is limited, and it is of great significance in engineering and production to realize accurate and real-time measurement of gas-liquid two-phase flow with small space occupation and low cost.

[0003] Flow pattern is an important tool for judging and dividing the structure of gas-liquid two-phase flow and has been applied in the field of energy industry. The measurement methods of gas-liquid two-phase flow include separation measurement method and non-separation measurement method. The separation measurement method has the advantage of accurate measurement, but also has the disadvantages of large occupation area and inability to measure in real time. The non-separation measurement method mainly includes electrical method (including conductivity method and capacitance method), optical method and radiation method, etc. The above methods have their own advantages, but also have disadvantages, such as electrical method is easy to be disturbed, optical method has strict requirements for the measured medium, radiation method is expensive and has radioactive danger, etc.

[0004] The bend flowmeter as a differential pressure flowmeter has been preliminarily applied in the measurement of single-phase flow and has achieved good results. Acoustic emission as a passive acoustic measurement method has the advantages of low energy consumption, no pollution and simple operation, and can obtain rich flow information in fluid measurement. SUMMARY

[0005] In view of the problems existing in the measurement of gas-liquid two-phase flow at present, on the basis of the existing research in the laboratory, the present application provides a gas-liquid two-phase flow measurement method based on bend and acoustic emission technology.

[0006] A gas-liquid two-phase flow measurement method based on bend and acoustic emission technology, characterized by comprising the following steps:

[0007] Step 0, install a differential pressure transmitter and an acoustic emission sensor at a horizontally arranged 90° gas-liquid two-phase flow bend, and collect the differential pressure signal and the acoustic emission signal, wherein the cross section of the bend can be circular or elliptical; install two sets of double parallel conductivity probes with a spacing of 15 cm before and after the two-phase flow straight pipe to measure the average liquid holdup;

[0008] Step 1, measure the average liquid holdup of the gas-liquid two-phase flow in the pipeline H L , calculate the gas-liquid two-phase flow mixing densityρ m ;

[0009] Step 2, measure the pressure difference between the inner and outer sides of the bend, the curvature radius of the bend, and the straight-line distance between the inner and outer pressure points of the bend, and calculate the parameters V C :

[0010]

[0011] wherein, V C is the instantaneous velocity of the gas and liquid phases passing through the 45° cross section of the bend, m / s; Δ P is the pressure difference between the inner and outer sides of the bend, Pa; R is the curvature radius at the axis of the bend, m; l e is the straight-line distance between the inner and outer pressure points of the bend, m;

[0012] Step 3, collect the acoustic emission signals of the gas-liquid two-phase flow in the bend, and identify the flow pattern of the gas-liquid two-phase flow in the pipeline;

[0013] Step 4, taking the parameters V C , the average liquid holdup H L , the superficial liquid velocity V SL , and the superficial gas velocity V SG as variables, using the dimensional analysis method, according to different flow patterns, the correlation of the parameters V C , the average liquid holdup H L , the superficial liquid velocity V SL , and the superficial gas velocity V SG is proposed, wherein the measurement correlation of the bubbly flow and the annular flow is shown in the following formula:

[0014]

[0015] The measurement correlation of the intermittent flow is shown in the following formula:

[0016]

[0017] After 50 kHz low-pass filtering of the collected acoustic emission signals, the effective voltage value RMS of the acoustic emission signals is calculated, and the correlation of RMS , the superficial liquid velocity V SL , and the superficial gas velocity V SG is established:

[0018]

[0019] wherein, k , b , x , y , z is a dimensionless number; G is a correction term, m / s; B is an intermittent flow correction term, m / s; a , C , m , n is a sound emission correlation formula coefficient;

[0020] By inputting multiple sets of the following variables: instantaneous velocity V C average liquid holdup H L superficial liquid velocity V SL superficial gas velocity V SG sound emission signal root mean square RMS, the three formulas are fitted to obtain the values of the parameters k , b , G , x , y , z , B , a , C , m , n .

[0021] Step 5, after the parameters are fitted in step 4, by inputting instantaneous velocity V C average liquid holdup H L sound emission signal root mean square RMS, the superficial liquid velocity V SL superficial gas velocity V SG is outputted, thereby completing the measurement of the gas-liquid two-phase flow rate.

[0022] In the step 0, the pressure taking position of the differential pressure transmitter is on both sides of the 45° section of the elbow.

[0023] In the step 0, the sound emission sensor is installed on both sides of the 45° section of the elbow.

[0024] In the step 1, the process of calculating the gas-liquid two-phase flow mixing density is as follows: the average liquid holdup of the gas-liquid two-phase flow in the pipeline is measured, and the gas-liquid two-phase flow mixing density is calculated by using the following formula:

[0025]

[0026] wherein, ρ m - gas-liquid two-phase flow mixing density, kg / m 3 ; H L - average liquid holdup in the sampling time, dimensionless; ρ L - liquid phase density in the two-phase flow, kg / m3; ρ G - gas phase density in the two-phase flow, kg / m3.

[0027] The step 3 is to collect the acoustic emission signals of the gas-liquid two-phase flow in the elbow pipe and identify the flow pattern of the gas-liquid two-phase flow in the pipe by using the prior art, which includes the gas-liquid two-phase flow pattern identification method based on acoustic emission-BP neural network described in the early patent CN111896616B of the laboratory.

[0028] In the step 3, the gas-liquid two-phase flow pattern includes bubbly flow, annular flow, intermittent flow and slug flow, wherein the slug flow can be classified as intermittent flow.

[0029] In the step 4, the acoustic emission signals of the gas-liquid two-phase flow in the elbow pipe are collected by the acoustic emission signal collection system, and the voltage value is calculated according to the following formula after 50 kHz low-pass filtering RMS :

[0030] wherein, N is the number of collected acoustic emission signals, V i represents the i-th collected acoustic emission signal.

[0031] In the step 4, the values of the parameters k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n in the formula flow calculation model are calculated according to experimental measurement, and the specific method is as follows: in the experiment, the elbow pipe with given size parameters is installed, and R, l e are obtained; the gas-liquid two-phase flow pattern is controlled to be the flow pattern to be measured, the known gas phase superficial velocity V SG and the liquid phase superficial velocity V SL, the differential pressure of the 45° cross-section of the elbow pipe, the acoustic emission signal and the average liquid holdup are obtained by using the differential pressure transmitter, the acoustic emission sensor and the double parallel conductance probe, and the apparent flow velocity is calculated V C With RMS A plurality of data points are collected, and the values of the parameters in the formula are fitted. If the size parameters of the measuring elbow pipe are changed, the above experiment is repeated, and the coefficients of the correlation formula in the flow calculation model corresponding to the elbow pipe of this type are fitted according to the measured data. For the elbow pipe flow measurement in the marine oil and gas industry, large-scale oil and gas multiphase flow meters at home and abroad can be used for experimental calibration.

[0032] In step 4, the apparent liquid velocity V SL , the apparent gas velocity V SG When the iteration solution diverges, the distance solution method is used for solution.

[0033] The traditional multiphase flow measurement method is to measure after separation by using a separator, but the separator is large and heavy, which will occupy a large space on the limited space of the offshore platform, and the separator is expensive and difficult to measure in real time. The patent CN115683250A of the laboratory has given a method for measuring the mixed flow of gas-liquid two-phase flow by using an elbow pipe and acoustic emission technology combined with an ELMAN neural network, which proves the feasibility of the elbow pipe-acoustic emission technology in multiphase flow measurement.

[0034] When the fluid passes through the elbow pipe, a radial pressure difference will be formed on the inner and outer walls of the elbow pipe due to the centrifugal force, and the size of the pressure difference is related to the physical properties of the fluid in the pipe and the gas-liquid phase motion state. On this basis, the relationship between the pressure difference inside and outside the elbow pipe, the liquid holdup, the acoustic emission signal and the apparent flow velocity is further studied, and a two-phase flow measurement method for on-line measurement of gas and liquid flow without separation is proposed. Compared with the commonly used single-phase measurement method after separation in the oil and gas industry, the present application has the advantages of simple structure, low measurement cost, real-time measurement and non-invasive measurement. By installing an acoustic emission sensor on the elbow flowmeter, the inner and outer differential pressures of the elbow pipe, the cross-sectional liquid holdup and the acoustic emission signal generated when the gas-liquid two-phase flow passes through the elbow pipe are measured, and the flow measurement model proposed in the present application is combined to realize the measurement of gas and liquid flow. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Schematic diagram of the elbow acoustic emission measurement system, wherein 1 is a differential pressure transmitter; 2 is an acoustic emission sensor; 3 is a preamplifier; 4 is an acoustic emission signal acquisition box; 5 is a computer; 6 is two groups of double parallel conductance probes installed with a front-to-back distance of 15 cm; and 7 is a horizontally installed pipeline.

[0036] Figure 2Schematic diagram of differential pressure and acoustic emission measurement element installation position, wherein, 1-differential pressure transmitter; 2-acoustic emission sensor; 8-horizontally installed 90° elbow pipe.

[0037] Figure 3 Program flow of the iterative solution method of the elbow acoustic emission gas-liquid two-phase flow flow measurement model.

[0038] Figure 4 Program flow chart of the distance solution method of the elbow acoustic emission gas-liquid two-phase flow flow measurement model. DETAILED DESCRIPTION

[0039] As Figure 1 shown, the hardware facilities applied by the present application include 1-differential pressure transmitter, 2-acoustic emission sensor, 3-pre-amplifier, 4-acoustic emission signal acquisition box, 5-computer, 6-two groups of double parallel conductivity probes installed with a front-to-back distance of 15 cm.

[0040] As Figure 2 shown, the differential pressure transmitter 1 is installed inside and outside the 45° cross section of the horizontally installed 90° elbow pipe, wherein the high pressure side is on the outside of the elbow pipe and the low pressure side is on the inside of the elbow pipe; the acoustic emission sensor 2 is installed on the top and bottom of the 45° cross section of the horizontally installed 90° elbow pipe. The elbow pipe and the experimental pipeline are made of stainless steel. The acoustic emission signal, the differential pressure signal and the conductivity probe electrical signal are collected by the acquisition card and input into the computer, and the flow rate is calculated by the program written in the computer. The specific method is as follows:

[0041] Step 0, install the differential pressure transmitter and the acoustic emission sensor at the horizontally installed 90° gas-liquid two-phase flow elbow pipe, and collect the differential pressure signal and the acoustic emission signal, wherein the cross section of the elbow pipe can be circular or elliptical; install two groups of double parallel conductivity probes with a front-to-back distance of 15 cm in front of the two-phase flow straight pipe to measure the average liquid holdup.

[0042] Step 1, measure the average liquid holdup of the gas-liquid two-phase flow in the pipeline, and calculate the gas-liquid two-phase flow mixture density by formula (1).

[0043] (1)

[0044] In the formula, ρ m - gas-liquid two-phase flow mixture density, kg / m 3 ; H L - average liquid holdup in the sampling time, dimensionless; ρ L - liquid phase density in the two-phase flow, kg / m3; ρ G - gas phase density in the two-phase flow, kg / m3.

[0045] Step 2, measure the pressure difference between the inner and outer sides of the elbow, the curvature radius of the elbow and the straight line distance between the inner and outer pressure points of the elbow, and calculate the parameter by using formula (2) V C :

[0046] (2)

[0047] In the formula, V C is the instantaneous velocity of gas and liquid phase through the 45° cross section of the elbow, m / s; Δ P is the pressure difference between the inner and outer sides of the elbow, Pa; R is the curvature radius at the axis of the elbow, m; l e is the straight line distance between the inner and outer pressure points of the elbow, m.

[0048] Step 3, collect the acoustic emission signals of the gas-liquid two-phase flow in the elbow, and identify the flow pattern of the gas-liquid two-phase flow in the pipeline.

[0049] Step 4, take the parameter V C , the average liquid holdup H L , the superficial liquid velocity V SL and the superficial gas velocity V SG as variables, and use the dimensional analysis method to propose the correlation formula of the parameter V C , the average liquid holdup H L and the superficial liquid velocity V SL , the superficial gas velocity V SG according to different flow patterns, wherein the measurement correlation formula corresponding to the bubbly flow and the annular flow is shown in formula (3), and the measurement correlation formula of the intermittent flow is shown in formula (4).

[0050] (3)

[0051] (4)

[0052] After 50 kHz low-pass filtering of the collected acoustic emission signals, the effective voltage value RMS of the acoustic emission signals is calculated, and the correlation formula of RMS , the superficial liquid velocity V SL and the superficial gas velocity V SG is established, as shown in formula (5):

[0053] (5)

[0054] In formula (3) to formula (5), k 、 b 、 x 、 y 、 z is a dimensionless number, which is different due to the structure of the elbow, the flowing medium and the flow pattern when fitting and solving; G is a correction term, m / s, which is subject to the zero drift of the instrument during measurement; B is an intermittent flow correction term, m / s, which is subject to the zero drift of the instrument during measurement and the fluctuation of the average liquid holdup within the sampling time; a 、 C 、 m 、 n is a sound emission correlation formula coefficient, which is different due to the fluid medium, the length of the sampling time, the pipeline parameters and the sound emission sensor parameters when fitting and solving.

[0055] By inputting multiple sets of the following variables: instantaneous velocity V C average liquid holdup H L superficial liquid velocity V SL superficial gas velocity V SG sound emission signal root mean square (RMS), formula (3) to formula (5) are fitted, so as to obtain the values of parameters k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n .

[0056] When the flow in the pipe is in the form of bubbly flow or annular flow, formula (3) and formula (5) are called by the program to form an equation group for simultaneous solving; when the flow in the pipe is intermittent flow, formula (4) and formula (5) are called by the program to form an equation group for simultaneous solving.

[0057] Step 5, after fitting and solving the parameters in step 4, by inputting instantaneous velocity V C average liquid holdup H L sound emission signal root mean square (RMS), the superficial liquid velocity V SL superficial gas velocity V SG is output, so as to complete the measurement of the gas-liquid two-phase flow.

[0058] In the above process, the model parameters need to be fitted and calibrated through multiple experiments to determine the values of the parameters k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n ; combining equation (3) and equation (5) to obtain a bubbly flow and annular flow flow measurement model, and combining equation (4) and equation (5) to obtain an intermittent flow flow measurement model. The solving method used to solve the measurement model is set, and the iterative solving method is preferentially used for solving, as shown in Figure 3 . When the iterative solution diverges, the distance solving method is used for solving, as shown in Figure 4 .

[0059] The values of the pressure difference Δ P , the average liquid holdup H L , the acoustic emission signal root mean square RMS, and the correlation formula parameter k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n are input into the computer, the flow pattern is divided by the acoustic emission-BP neural network method, then the apparent liquid velocity V SL and the apparent gas velocity V SG are solved by equations (3)-(5), and the apparent gas velocity and the apparent liquid velocity are output.

[0060] Embodiment

[0061] In this embodiment, two types of stainless steel bends are used, and the specific structural parameters of the two bends are shown in Table 1.

[0062] After determining the structural parameters of the bend, the parameters k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C in equations (3)-(5) are first calibrated.m , n The specific method is as follows:

[0063] 1) The experiments under various flow patterns such as bubble flow, annular flow and intermittent flow are carried out by using the sound emission-BP neural network flow pattern recognition system of the patent CN111896616B of the laboratory;

[0064] 2) The average liquid holdup of the pipeline is measured by using the double parallel conductivity probe H L , the pressure difference Δ of the inner and outer sides of the elbow pipe is measured by using the differential pressure sensor P , and the sound signal of the fluid flowing through the elbow pipe is measured by using the sound emission sensor;

[0065] 3) The mixed density is calculated by using formula (1) ρ m , the cross-sectional velocity is calculated by using formula (2) V C , the sound emission signal is subjected to 50 kHz low-pass filtering, and the effective value is calculated according to formula (6) RMS:

[0066] (6)

[0067] 4) The values of the parameters in formula (3) to formula (5) k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n are solved by using the binary fitting method according to the experimental data;

[0068] 5) The measured values of the parameters k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n are substituted into formula (3) to formula (5), and the numerical method is used to solve the superficial gas velocity V SG and the superficial liquid velocity V SLSolving. When the pipe flow is bubbly flow or annular flow pattern, the program calls equation (3) and equation (5) to form a system of equations for simultaneous solution; when the pipe flow is intermittent flow, the program calls equation (4) and equation (5) to form a system of equations for simultaneous solution. Through experimental calculation, the relative errors of the prediction results of the two algorithms are basically the same, and the Newton iteration method is relatively simple to calculate, so the Newton iteration method is preferred for solving, and when the iteration diverges, the distance solving method is used to solve.

[0069] The two types of elbow pipes used in the embodiment have specific structural parameters as shown in Table 1.

[0070] Table 1 Structural parameters of two types of elbow pipes

[0071] Bend code Radius of curvature R / mm 45° cross-sectional shape Pipe inner diameter d / mm Pressure tapping distance l e / mm]] R39 39 Circular 26 29 R64 64 Elliptical 26 25.4

[0072] The measured parameters of the two elbow pipes in the embodiment are as follows. k 、 b 、 G 、 x 、 y 、 z 、 B 、 a 、 C 、 m 、 n The values of 4) to 7) are shown in Tables 2-4.

[0073] Table 2 Parameter values of the measured correlation formula in bubbly flow

[0074] R39 0.7972 0.2739 0.1315 7.05 16.89 1.16 1.68 R64 0.9775 0.3603 0.196 2.55 2.82 1.15 1.56

[0075] Table 3 Parameter values of the measured correlation formula in annular flow

[0076] R39 13.26 4.93 x 10 -3 ]]> -0.1542 0.17 -37.5 2.59 0.57 R64 11.49 9.06 x 10 -3 ]]> 0.2361 0.91 -38.2 1.70 0.32

[0077] Table 4 Parameter values of the measured correlation formula in intermittent flow

[0078] R39 0.9461 -0.1278 0.5 0.4 19.3 -1.20 0.90 0.65 R64 0.6797 -0.1639 0.6 0.2 5.91 -0.83 0.94 0.65

[0079] The measurement results are shown in Tables 5-10, only part of the measurement results are listed due to the limited space. The average absolute percentage measurement error of the measurement model in two elbow pipes and three flow patterns is shown in Table 11, it can be seen that the measurement effect is good. The measurement effect of R64 elbow pipe is slightly worse than that of R39 elbow pipe, the reasons may include: one is that the curvature radius of the elbow pipe is larger, which reduces the centrifugal force of the fluid passing through the elbow pipe; two is that the 45° cross-sectional shape is elliptical due to the pipe processing technology, which weakens the secondary flow in the elbow pipe. The intermittent flow measurement effect is slightly worse, because intermittent flow has strong randomness, which leads to strong fluctuation of liquid holdup, so the measurement effect depends on the sampling time, the hardware performance of the acoustic emission system is limited in this experiment, the 15 second sampling time is short, when the liquid slug frequency is low, the data is not representative, prolonging the sampling time is expected to improve the measurement accuracy. In actual industrial application, high-precision elbow pipe processing technology is used, high-performance acoustic emission acquisition instrument is used, and sampling time is prolonged, the technical solution of the present application can obtain higher measurement accuracy, and realize the compact space, low-cost oil and gas flow measurement demand of offshore oil and gas field.

[0080] Table 5 R39 elbow pipe bubble flow measurement results

[0081] Serial number V SG-real , m / s ​ V SG-cal , m / s ​ δV SG , %]]> ​ V SL-real , m / s ​ V SL-cal , m / s ​ δV SL , %]]> ​ 1 0.32 0.38 15.51 1.46 1.45 -0.69 2 0.32 0.33 3.03 2.09 2.11 0.94 3 0.54 0.46 -17.75 1.27 1.25 -1.60 4 0.54 0.72 25.97 1.67 1.56 -7.05 5 0.54 0.58 6.89 2.09 2.05 -1.95 6 0.69 0.95 27.95 1.46 1.32 -10.61 7 0.71 0.6 -18.33 2.09 2.05 -1.95 8 1.03 1.2 14.17 1.69 1.63 -3.68 9 1.039 1.046 0.67 1.878 1.89 0.63 10 2.033 1.896 -7.22 1.657 1.70 2.53

[0082] Note: in the above table, V SG-real - the apparent gas velocity measured in the experiment; V SG-cal - the apparent gas velocity calculated by the model; V SL-real - the apparent liquid velocity measured in the experiment; V SL-cal - the apparent liquid velocity calculated by the model; δV SG - the relative error of the gas phase flow measurement; δ V SL - the relative error of the liquid phase flow measurement. The same below.

[0083] Table 6 R64 elbow pipe bubble flow measurement results

[0084] Serial number V SG-real , m / s ​ V SG-cal , m / s ​ δV SG , %]]> ​ V SL-real , m / s ​ V SL-cal , m / s ​ δV SL , %]]> ​ 1 0.28 0.23 -21.74 1.24 1.28 3.13 2 0.28 0.33 15.15 1.46 1.42 -2.82 3 0.53 0.64 17.19 1.27 1.24 -2.42 4 0.53 0.54 1.85 1.47 1.46 -0.68 5 0.72 0.73 1.37 1.47 1.42 -3.52 6 0.71 0.79 10.13 1.67 1.64 -1.83 7 1.02 1.03 0.97 1.66 1.69 1.78 8 1.02 1.14 10.53 1.88 1.86 -1.08 9 2.04 1.82 -12.09 1.67 1.82 8.24 10 2.02 2.04 0.98 1.89 1.83 -3.28

[0085] Table 7 R39 elbow pipe annular flow measurement results

[0086] Serial number V SG-real , m / s ​ V SG-cal , m / s ​ δV SG , %]]> ​ V SL-real , m / s ​ V SL-cal , m / s ​ δV SL , %]]> ​ 1 17.23 16.75 -2.87 0.10 0.12 16.67 2 17.07 17.39 1.84 0.21 0.19 -10.53 3 21.18 20.35 -4.08 0.22 0.24 8.33 4 21.11 20.42 -3.38 0.33 0.35 5.71 5 21.29 20.96 -1.57 0.41 0.43 4.65 6 21.24 21.40 0.75 0.52 0.50 -4.00 7 25.56 23.87 -7.08 0.10 0.13 23.08 8 25.41 25.06 -1.40 0.21 0.21 -5.00 9 25.64 25.57 -0.27 0.32 0.33 3.03 10 25.44 25.81 1.43 0.42 0.41 -2.44

[0087] Table 8 R64 elbow pipe annular flow measurement results

[0088] Serial number V SG-real , m / s ​ V SG-cal , m / s ​ δV SG , %]]> ​ V SL-real , m / s ​ V SL-cal , m / s ​ δV SL ,% ​ 1 16.84 17.15 1.81 0.32 0.3 -6.67 2 16.99 17.17 1.05 0.42 0.44 4.55 3 21.26 21.78 2.39 0.22 0.19 -15.79 4 21.33 21.74 1.89 0.32 0.31 -3.23 5 21.35 21.48 0.61 0.44 0.45 2.22 6 21.31 21.03 -1.33 0.52 0.55 5.45 7 25.42 24.71 -2.87 0.11 0.13 15.38 8 24.53 26.81 8.50 0.21 0.18 -16.67 9 25.43 27.22 6.58 0.32 0.27 -18.52 10 25.35 25.94 2.27 0.43 0.42 -2.38

[0089] Table 9 R39 elbow intermittent flow measurement results

[0090] Serial number V SG-real , m / s ​ V SG-cal , m / s ​ δV SG , %]]> ​ V SL-real , m / s ​ V SL-cal , m / s ​ δV SL , %]]> ​ 1 1.05 1.03 -1.94 0.31 0.29 -6.90 2 1.02 0.91 -12.09 0.43 0.57 24.56 3 2.01 2.42 16.94 0.21 0.17 -23.53 4 2.02 1.76 -14.77 0.31 0.44 29.55 5 3.05 4.21 27.55 0.22 0.18 -22.22 6 3.05 4.01 23.94 0.31 0.25 -24.00 7 5.01 4.21 -19.00 0.43 0.58 25.86 8 4.99 6.23 19.90 0.52 0.43 -20.93 9 6.98 7.71 9.47 1.06 0.89 -19.10 10 6.94 8.8 21.14 1.21 0.94 -28.72

[0091] Table 10 R64 elbow intermittent flow measurement results

[0092] Serial number V SG-real , m / s ​ V SG-cal , m / s ​ δV SG , %]]> ​ V SL-real , m / s ​ V SL-cal , m / s ​ δV SL , %]] ​ 1 1.00 0.86 -16.28 0.21 0.29 27.59 2 1.00 0.83 -20.48 0.33 0.38 13.16 3 2.03 2.87 29.27 0.41 0.34 -20.59 4 2.00 1.72 -16.28 0.54 0.77 29.87 5 3.12 3.84 18.75 0.53 0.42 -26.19 6 3.15 3.81 17.32 0.63 0.55 -14.55 7 5.11 4.66 -9.66 0.63 0.71 11.27 8 5.08 4.52 -12.39 0.84 0.76 -10.53 9 7.14 8.03 11.08 0.84 0.71 -18.31 10 7.11 7.24 1.80 1.05 1.1 4.55

[0093] Table 11 Average absolute percentage error of the elbow acoustic emission gas-liquid two-phase flow measurement model

[0094]

Claims

1. A method for measuring the flow rate of a gas-liquid two-phase flow based on a bent pipe and acoustic emission technology, characterized in that: Includes the following steps: Step 0: Install a differential pressure transmitter and an acoustic emission sensor at the 90° bend of the horizontally set gas-liquid two-phase flow pipe, and collect the differential pressure signal and acoustic emission signal. Install two sets of double parallel conductivity probes at a distance of 15cm before and after the two-phase flow straight pipe to measure the average liquid holdup. Step 1: Measure the average liquid holdup of the gas-liquid two-phase flow in the pipeline. H L Calculate the mixing density of gas-liquid two-phase flow ρ m ; Step 2: Measure the pressure difference between the inside and outside of the bend, the radius of curvature of the bend, and the straight-line distance between the pressure taps on the inside and outside of the bend, and calculate the parameters. V C : In the formula, V C Δ is the instantaneous velocity of the gas and liquid phases at the 45° section of the bend in the pipe, in m / s; P The pressure difference between the inside and outside of the bend, in Pa; R Let be the radius of curvature at the axis of the bend, in meters (m). l e The straight-line distance between the pressure tapping points on the inside and outside of the bend, in meters; Step 3: Collect acoustic emission signals of the gas-liquid two-phase flow in the bend and identify the flow pattern of the gas-liquid two-phase flow in the pipe; Step 4: Set parameters V C Average liquid holdup H L Apparent fluid velocity V SL and apparent gas velocity V SG As variables, dimensional analysis is used to propose parameters based on different flow patterns. V C Average liquid holdup H L With apparent fluid velocity V SL Apparent gas velocity V SG The correlations, where the measurement correlations for bubbly flow and annular flow are shown in the following equations: The correlation for intermittent flow measurement is shown in the following equation: After performing a 50kHz low-pass filter on the acquired acoustic emission signal, the effective voltage value of the acoustic emission signal is calculated. RMS ,Establish RMS With apparent fluid velocity V SL and apparent gas velocity V SG Relationship: In the formula, k , b , x , y , z It is a dimensionless number; G For correction terms, m / s; B For intermittent flow correction, m / s; a , C , m , n These are the acoustic emission correlation coefficients; By inputting multiple sets of the following variables: instantaneous velocity V C Average liquid holdup H L Apparent fluid velocity V SL Apparent gas velocity V SG The root mean square (RMS) of the acoustic emission signal is used to fit the three formulas to obtain the parameters. k , b , G , x , y , z , B , a , C , m , n The value; Step 5: After obtaining the parameters through fitting in Step 4, input the instantaneous velocity. V C Average liquid holdup H L The root mean square (RMS) of the acoustic emission signal is used to output the apparent liquid velocity. V SL Apparent gas velocity V SG This allows for the measurement of the flow rate of the gas-liquid two-phase flow.

2. The method as described in claim 1, characterized in that: In step 0, the differential pressure transmitter taps pressure on both the inside and outside sides of the 45° section of the bend.

3. The method as described in claim 1, characterized in that: In step 0, the acoustic emission sensor is installed on the upper and lower sides of the 45° section of the bend.

4. The method as described in claim 1, characterized in that: In step 0, the cross-section at the bend includes a circular cross-section or an elliptical cross-section.

5. The method as described in claim 1, characterized in that: In step 1, the process of calculating the gas-liquid two-phase flow mixing density is as follows: the average liquid holdup of the gas-liquid two-phase flow in the pipeline is measured, and the gas-liquid two-phase flow mixing density is calculated using the following formula: In the formula, ρ m -Gas-liquid two-phase flow mixing density, kg / m³ 3 ; H L -Average liquid holdup during the sampling period, dimensionless; ρ L -Liquid phase density in two-phase flow, kg / m3; ρ G - Gas phase density in two-phase flow, kg / m3.

6. The method as described in claim 1, characterized in that: Step 3 involves using existing technology to collect acoustic emission signals of the gas-liquid two-phase flow in the bend and to identify the flow pattern of the gas-liquid two-phase flow in the pipeline.

7. The method as described in claim 6, characterized in that: In step 3, the gas-liquid two-phase flow patterns include bubbly flow, annular flow, intermittent flow, and slug flow, among which slug flow can be classified as intermittent flow.

8. The method as described in claim 1, characterized in that: In step 4, the effective voltage value is calculated. RMS The method is as follows: Acoustic emission signals of the gas-liquid two-phase flow in the bend are acquired using an acoustic emission signal acquisition system. After 50kHz low-pass filtering, the effective voltage value is calculated according to the following formula. RMS : , Where N is the number of acoustic emission signals collected, and V i This represents the i-th acoustic emission signal collected.

9. The method as described in claim 1, characterized in that: In step 4, the parameters in the flow calculation model composed of the formula are... k , b , G , x , y , z , B , a , C , m , n The values ​​are obtained through experimental measurements and calculations. Specifically, in the experiment, a bent pipe with given dimensional parameters is installed to obtain R and l. e Controlling the gas-liquid two-phase flow pattern to the desired flow pattern involves changing the known apparent velocity of the gas phase. V SG and apparent velocity of liquid phase V SL The differential pressure, acoustic emission signal, and average liquid holdup at a 45° cross-section of the bend were obtained using a differential pressure transmitter, acoustic emission sensor, and dual parallel conductivity probes. The results were then calculated. V C and RMS Multiple data points were collected, and the values ​​of the parameters in the formula were obtained by fitting the data.

10. The method of claim 9, characterized in that: In step 4, the apparent fluid velocity is calculated. V SL Apparent gas velocity V SG When the problem is solved, the iterative solution method should be used first. When the iterative solution diverges, the distance solution method should be used.

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