Gas-liquid two-phase slug flow related flow measuring device and method based on vibration vision

Abstract

The invention relates to flow measurement, in particular to a gas-liquid two-phase slug flow related flow measurement device and method based on vibration vision, and aims to solve the problem that an existing two-phase flow meter cannot measure the flow working condition of slug flow with fluctuation characteristics. According to the device, a vibration probe is fixed on a pipeline through a base, a vibration needle is fixed in the base through a sealing piece, one end of the vibration needle extends into the pipeline to detect slug flow fluctuation, a magnet is arranged at the other end of the vibration needle and right faces a magnetic visual mark, magnetic force exists between the magnet and the visual mark, and the magnetic force enables the visual mark and the vibration needle to vibrate synchronously. Based on a dynamic image or video of vibration of the visual mark, a vibration signal of the visual mark can be obtained; on-line measurement of gas-liquid two-phase dynamic flow can be realized by utilizing vibration signals of visual marks corresponding to the double vibration probes positioned on the upstream and downstream of the slug flow, so that flow measurement of the slug flow is not influenced by liquid phase viscosity on probe signals and is not limited by whether the liquid phase is conductive or not, light guide and the like, and the device and the method are suitable for water-gas two-phase flow and can also be used for measuring the flow of the slug flow. And the device is also suitable for oil-gas two-phase flow.

Description

Technical Field

[0001] The present invention relates to the field of flow measurement technology, and in particular to a flow measurement device and method for gas-liquid two-phase slug flow based on vibration vision. Background Art

[0002] Slug flow is one of the main flow patterns of gas-liquid two-phase flow in pipelines. There is a two-phase slug flow of steam and water in power engineering, a two-phase slug flow of natural gas and oil in petroleum engineering, and a two-phase slug flow of gas and organic fluid in chemical engineering. The alternating appearance of gas and liquid slugs causes flow fluctuations of the gas-liquid two-phase, which is the basic characteristic of slug flow. This fluctuation characteristic affects the measurement accuracy of the multiphase flowmeter.

[0003] For the flow measurement of two-phase flow, the existing technical solutions use pressure drop characteristics, conductivity and capacitance characteristics, density characteristics, heat transfer characteristics, ultrasonic characteristics, etc. to measure the phase content or two-phase flow. These technical solutions have their limitations in practical applications. For example, orifice plates, elbows, venturi tubes, etc. can use the pressure drop characteristics of two-phase flow to measure the flow of two-phase flow. This type of differential pressure flow measurement device is suitable for use under flow conditions with stable differential pressure, while slug flow will cause obvious differential pressure or pressure drop fluctuations due to flow fluctuations. The error or uncertainty caused by this is very large, making it difficult for the differential pressure measurement device to ensure the allowed accuracy and reliability for the flow measurement of slug flow. The conductivity and capacitance type two-phase flow measurement technology uses the conductivity and capacitance difference between gas and liquid to measure the flow of two-phase flow. This type of method has special requirements for the conductivity of the liquid and is usually applicable to gas-liquid two-phase flow of gas and water. If the liquid is oil, both the oil and gas phases are insulators and there is no difference in conductivity. Therefore, the conductivity and capacitance type technical solution is not suitable for the flow measurement of oil and gas two-phase flow. Gamma rays, X-rays, etc. use the different absorption rates of the different densities of the gas and liquid phases to measure the phase content of the gas and liquid phases. In view of the public safety requirements of nuclear radiation, such methods can only be applied in a small range and are difficult to popularize on a large scale. Two-phase flow meters using heat transfer characteristics and ultrasonic characteristics, due to the thermal relaxation and momentum relaxation effects between the gas and liquid phases, the heat transfer response and acoustic response of the gas-liquid two-phase flow will be affected by the slug flow fluctuation characteristics, especially the rapid attenuation of ultrasonic waves when passing through the gas phase. Therefore, two-phase flow meters using heat transfer characteristics and ultrasonic characteristics are not suitable for slug flow, which has obvious fluctuation characteristics.

[0004] In view of the limitations of existing flow measurement methods for gas-liquid two-phase flow, especially when applied to the two-phase slug flow, these existing flow metering schemes often fail due to the fluctuation characteristics of the gas-liquid two-phase in the slug flow. The development of a two-phase flow measurement device that is not affected by the fluctuation characteristics of the gas-liquid two-phase in the slug flow, and is not affected by electrical conductivity, heat transfer characteristics, and acoustic characteristics, has engineering practical value for solving the dynamic flow measurement of two-phase slug flow, especially the two-phase slug flow of natural gas and oil in petroleum engineering, and the two-phase slug flow of gas and organic working fluids in chemical engineering. Summary of the invention

[0005] The purpose of this case is to propose a gas-liquid two-phase slug flow related flow measurement device based on vibration vision, which uses the fluctuation characteristics of the two-phase slug flow to measure the dynamic flow of the gas-liquid two-phase online, so as to solve the problem that the conventional two-phase flowmeter in the prior art cannot be used to measure the flow condition with obvious fluctuation characteristics such as slug flow. The device is based on the basic principle that the vibration signal of the vibration probe depends on the fluctuation signal of the slug flow, and the moving speed of the gas bomb in the slug flow is obtained by cross-correlation analysis of the vibration signals of the dual vibration probes. Further, based on the multiphase flow theory such as the functional relationship between the moving speed of the gas bomb and the mixed flow velocity of the two-phase flow, the volume flow rate of the gas phase and the volume flow rate of the liquid phase are finally measured and calculated.

[0006] In order to achieve the above technical objectives, the specific technical scheme of this case is as follows.

[0007] On the first aspect, this case proposes a flow measurement device for gas-liquid two-phase slug flow based on vibration vision, the measuring device includes a dual vibration probe, a signal acquisition module, and an analysis module; each vibration probe is fixed on the pipeline of the slug flow by means of a base, a seal is used to fix a vibration needle in the base, one end of the vibration needle is in contact with the slug flow to detect the fluctuation of the gas-liquid two-phase slug flow, and the other end of the vibration needle has a magnet, the magnet is facing a magnetic visual mark, there is a magnetic force between the magnet and the visual mark, and the magnetic force causes the visual mark to vibrate synchronously with the vibration needle; the signal acquisition module is configured to obtain a vibration signal of the visual mark based on a dynamic image or video of the vibration of the visual mark; the analysis module is configured to use the vibration signal of the visual mark corresponding to the dual vibration probes located upstream and downstream of the slug flow to achieve online measurement of the dynamic flow of the gas-liquid two-phase.

[0008] In one embodiment of the technical solution of the above-mentioned device, the sealing member includes a sealing ring, a sealing ring cover, and a sealing flange. The vibrating needle passes through the sealing ring, the sealing ring cover, and the sealing flange. The sealing ring is pressed against the sealing flange by tightening the sealing ring cover. The vibrating needle contacts the sealing ring but not the sealing cover or the sealing flange.

[0009] In one embodiment of the technical solution of the above-mentioned device, one end of the base has two sections of internal threads of different sizes, the larger internal thread is used to connect to the pipeline, and the smaller internal thread is used to connect to the external thread of the seal; the other end of the base has an external thread, which is connected to the internal thread of the cap, and the cap has a transparent visual marking box, and the transparent visual marking box has a visual mark inside.

[0010] In one implementation of the above device technical solution, the cap is made of low magnetic permeability material.

[0011] In one embodiment of the technical solution of the above-mentioned device, one end of the visual mark is fixed on the inner wall of the transparent visual mark box, and the other end is suspended in the air. The suspended end is closer to the magnet than the fixed end. The suspended end is magnetic and has color characteristics and / or shape characteristics for identification.

[0012] In one embodiment of the above device technical solution, the visual marker is a filament or a capillary.

[0013] In one embodiment of the technical solution of the above-mentioned device, the device also includes a camera for obtaining dynamic images or videos of the vibration of the visual marker. By performing visual analysis on the dynamic images or videos of the vibration of the visual marker, the vibration signal of the visual marker can be obtained.

[0014] In one embodiment of the technical solution of the above-mentioned device, the processing process of the analysis module includes: based on the vibration signal of the visual mark corresponding to the dual vibration probe, obtaining the distribution of the correlation coefficient with the transit time through cross-correlation analysis, taking the transit time corresponding to the maximum correlation coefficient as the time for the gas bomb to pass through the dual vibration probe, and dividing the installation spacing of the dual vibration probe by the transit time to obtain the moving speed of the gas bomb; using the functional relationship between the moving speed of the gas bomb and the mixed flow velocity of the two-phase flow, calculating the mixed flow velocity of the two-phase flow, multiplying it by the cross-sectional area of ​​the pipeline to obtain the total volume flow rate of the gas and liquid phases; based on the vibration signal of the visual mark corresponding to the dual vibration probe, obtaining the fluctuation frequency of the slug flow through frequency analysis; using the functional relationship between the fluctuation frequency, the mixed flow velocity and the volume liquid content, calculating the volume liquid content of the gas and liquid phases; multiplying the calculated volume liquid content of the gas and liquid phases by the total volume flow rate of the gas and liquid phases to obtain the volume flow rate of the liquid phase, and subtracting the volume flow rate of the liquid phase from the total volume flow rate of the gas and liquid phases to obtain the volume flow rate of the gas phase.

[0015] In one implementation of the technical solution of the above device, the installation spacing of the dual vibration probes is 2 times to 20 times the pipe diameter.

[0016] Secondly, this case proposes a method for measuring the flow rate related to a gas-liquid two-phase slug flow based on vibration vision, the method comprising: making a visual marker generate a vibration corresponding to the fluctuation of the gas-liquid two-phase slug flow, and then obtaining a vibration signal of the visual marker based on a dynamic image or video of the visual marker vibration; obtaining the vibration signals of the visual markers corresponding to two locations upstream and downstream of the gas-liquid two-phase slug flow, performing cross-correlation analysis and frequency analysis, and realizing online measurement of the dynamic flow rate of the gas-liquid two-phase.

[0017] The beneficial technical effects of this case are as follows: 1) The measuring device of this case uses the fluctuation characteristics of the slug flow to implement the measurement of the two-phase flow, so it will not fail due to the fluctuation characteristics of the slug flow, and does not require auxiliary equipment such as a gas-liquid separator. It can be installed online on the pipeline to measure the dynamic flow of the gas phase and the liquid phase in the slug flow in real time. 2) The measuring device of this case is not affected by the viscosity of the liquid phase on the probe signal, nor is it restricted by whether the liquid phase is conductive or light-conductive. It is suitable for both water-gas two-phase flow and oil-gas two-phase flow, especially the two-phase slug flow of natural gas and oil in petroleum engineering, and the two-phase slug flow of gas and organic working fluid in chemical engineering. The device is conducive to engineering and technical personnel to use the fluctuation characteristics of the slug flow to measure the dynamic flow of the gas phase and the liquid phase in the slug flow online under the fluctuating working conditions of the slug flow, and provide dynamic flow data of the gas phase and the liquid phase for implementing process control, metering and handover, and optimizing production parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 , one A schematic diagram of device installation and a schematic diagram of device structure in an embodiment.

[0020] Figure 2 , one Schematic diagram of the vibration signal of the dual vibration probe in this embodiment.

[0021] Figure 3 , one Schematic diagram of the correlation coefficient and transit time of the dual vibration probe vibration vision in this embodiment.

[0022] Figure 1In the figure, 1 is a vibration needle, 2 is a base, 3 is an internal thread on the base connected to the pipe base, 4 is an external thread on the sealing ring cover, 5 is an internal thread on the base connected to the sealing ring cover, 6 is a sealing ring cover, 7 is a sealing ring, 8 is a sealing flange, 9 is an external thread on the base connected to the cap, 10 is an internal thread on the cap, 11 is a cap, 12 is a magnet, 13 is a visual marker, 14 is a transparent visual marker box, 15 is a high-speed camera, 16 is a signal acquisition module, 17 is a cross-correlation analysis module, 18 is a frequency analysis module of the vibration signal, 19 is a flow calculation module, 20 is a downstream vibration probe, 21 is an upstream vibration probe, 22 is a pipeline, 23 is a liquid bomb, and 24 is a gas bomb. DETAILED DESCRIPTION

[0023] In view of the limitations of existing flow measurement methods for gas-liquid two-phase flow, especially when applied to the flow type of two-phase slug flow, these existing flow metering schemes often fail due to the fluctuation characteristics of the gas-liquid two-phase in the slug flow. This case proposes a gas-liquid two-phase slug flow related flow measurement device based on vibration vision, the device includes a visual marker, the vibration generated by the visual marker corresponds to the fluctuation of the gas-liquid two-phase slug flow, and then based on the dynamic image or video of the visual marker vibration, the vibration signal of the visual marker is obtained. The device obtains the vibration signals of the visual markers corresponding to the upstream and downstream of the gas-liquid two-phase slug flow, performs cross-correlation analysis and frequency analysis, realizes online measurement of the dynamic flow of the gas-liquid two-phase, and is not affected by conductivity, heat transfer characteristics and acoustic characteristics. It has engineering practical value for solving the dynamic flow measurement of two-phase slug flow, especially the two-phase slug flow of natural gas and oil in petroleum engineering, the two-phase slug flow of gas and organic working fluid in chemical engineering, etc.

[0024] The following will be combined with the accompanying drawings to clearly and completely describe how the device of this case overcomes the influence of electrical conductivity, heat transfer characteristics and acoustic characteristics to measure the dynamic flow of gas-liquid two phases online. Obviously, the described implementation is only a part of the implementation of this case, not all of the implementations. Based on the implementation in this case, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] (I) Measuring device

[0026] The measuring device includes a dual vibration probe, a signal acquisition module, and an analysis module; each vibration probe is fixed on the pipeline of the slug flow by a base, and a vibrating needle is fixed in the base by a seal, one end of the vibrating needle is in contact with the slug flow to detect the fluctuation of the gas-liquid two-phase slug flow, and the other end of the vibrating needle has a magnet, and the magnet is facing the magnetic visual mark. There is a magnetic force between the magnet and the visual mark, and the magnetic force causes the visual mark and the vibrating needle to vibrate synchronously; the signal acquisition module is configured to obtain the vibration signal of the visual mark based on the dynamic image or video of the visual mark vibration; the analysis module is configured to use the vibration signal of the visual mark corresponding to the dual vibration probes located upstream and downstream of the slug flow to realize online measurement of the dynamic flow rate of the gas-liquid two-phase.

[0027] See also Figure 1 There is a slug flow in the pipe (22), and the gas bomb (24) and the liquid bomb (23) flow alternately, which is the basic characteristic of the gas-liquid two-phase slug flow. Since the physical properties such as viscosity and inertia of the liquid bomb and the gas bomb are significantly different, the slug flow has obvious wave characteristics.

[0028] The downstream vibration probe (20) and the upstream vibration probe (21) of the same structure are installed at the downstream and upstream of the pipeline (22) at a spacing of 2 times to 20 times the pipe diameter, so that the gas-liquid two-phase flow rate can be accurately calculated. For example, if the pipe diameter is 25 mm, the spacing is 2 times the pipe diameter and the installation spacing is 50 mm, the spacing is 12 times the pipe diameter and the installation spacing is 300 mm, and the spacing is 20 times the pipe diameter and the installation spacing is 500 mm. The dual vibration probes can be welded to the pipe wall, installed on the pipe through a valve, or installed through a short pipe with a thread.

[0029] Figure 1 The illustrated dual vibration probe is installed on the pipe (22) through the base (2) in a threaded manner.

[0030] The base (2) is a hollow gyroscope. One end of the base (2) has two sections of internal threads of different sizes and a sealing flange (8) in the middle. The two are integrated with the base (2). The larger internal thread base is an internal thread (3) connected to the pipe base, and the smaller internal thread is an internal thread (5) on the base connected to the sealing ring gland. The sealing flange (8) protrudes toward the center of the base. The other end of the base (2) has an external thread (9) connected to it, which matches the internal thread (10) on the cap.

[0031] The cover cap (8) seals the vibrating needle (1) in the base (2), thereby protecting the vibrating needle (1) from external interference and preventing the gas-liquid two-phase fluid in the pipeline (22) from leaking out, thus providing a safety protection function for the vibrating needle (1).

[0032] The vibrating needle (1) is fixed inside the base (2) through a sealing member. The sealing member includes a sealing ring (7), a sealing ring pressure cover (6), and a sealing flange (8). The vibrating needle (1) passes through the sealing ring (7), the sealing ring pressure cover (6), and the sealing flange (8), and the sealing ring (7) is sleeved on the middle part of the vibrating needle (1). The vibrating needle (1) is in pre-tightened contact with the sealing ring (7), and the sealing ring (7) is in pre-tightened contact with the base (2). The sealing ring pressure cover (6) has an external thread (4) that matches the internal thread (5) on the base connected to the sealing ring pressure cover. By tightening the sealing ring pressure cover (6), the sealing ring (7) can be pressed against the sealing flange (8), thereby fixing the vibrating needle (1) inside the base (2). In this sealed fixing structure, the vibrating needle (1) only contacts with the sealing ring (7), and does not contact with the sealing flange (8), the sealing ring pressure cover (6), and other base components, so that the vibrating needle (1) has sufficient vibration space.

[0033] A permanent magnet (12) is embedded at one end of the vibrating needle (1), and the permanent magnet (12) faces the magnetic visual mark (13). The permanent magnet (12) and the visual mark (13) are on both sides of the cap (11). The cap (11) is made of a material with low magnetic permeability, such as low magnetic stainless steel, to avoid magnetic shielding, so that the vibration signal of the vibrating needle can be transmitted to the visual mark (13) outside the cap (11) through magnetic force, so that it vibrates together with the vibrating needle.

[0034] The visual marker (13) is a filament or a capillary tube, one end of which is suspended in the air and vibrates together with the vibrating needle (1) under the action of magnetic force. The suspended end is colored and magnetic. There is a shape on the suspended end that is easy to identify its vibration, such as a "⊥"-shaped or "cross"-shaped horizontal line located at the suspended end, such as an arrow below "↓" located at the suspended end, etc., which can facilitate identification of vibration. The other end of the visual marker (13) is fixed to the inner wall of a transparent visual marker box (14). The transparent visual marker box (14) is located on the cap (11) so that the suspended section of the visual marker (13) faces the permanent magnet (12).

[0035] The vibration probe is installed on the pipeline. During the installation, a hole is opened on the pipe wall. The hole corresponds to the hollow part of the base (2) and the axes of the two are located on the same straight line. The vibration needle (1) exposed by the vibration probe extends into the pipeline (22) and contacts the slug flow. Under the flow pattern of the slug flow, when the gas bomb and liquid bomb that flow alternately hit the vibration needle respectively, since the kinetic energy of the liquid bomb is significantly greater than the kinetic energy of the gas bomb, the kinetic energy difference between the liquid bomb and the gas bomb will produce different dynamic pressures on the probe, causing the vibration needle (1) to produce a vibration effect, thereby detecting the fluctuation of the gas-liquid two-phase slug flow through the vibration of the vibration needle. Since the vibration of the vibration needle is synchronized with the vibration of the visual mark, the vibration of the visual mark (13) can be used as a reflection of the fluctuation characteristics of the slug flow, and on this basis, the dynamic flow rate of the two-phase flow is measured.

[0036] A high-speed camera (15) is used to capture dynamic image signals or video signals of the visual marker (13) of the dual vibration probes (downstream vibration probe (20), upstream vibration probe (21)). Then, a signal acquisition module (16) uses a visual signal analysis method to track and extract the displacement of the visual marker in each frame of the dynamic image, thereby extracting a vibration signal.

[0037] Next, an analysis module is used to realize online measurement of the dynamic flow of gas and liquid phases by using the vibration signals of the visual markers corresponding to the dual vibration probes located upstream and downstream of the slug flow. The analysis module includes a cross-correlation analysis module (17), a frequency analysis module (18), and a flow calculation module (19).

[0038] Specifically, firstly, the cross-correlation analysis module (17) and the frequency analysis module (18) are used to perform cross-correlation analysis and frequency analysis on the vibration signal, and the moving speed of the gas bomb and the fluctuation frequency of the slug flow can be obtained respectively. The cross-correlation analysis module (17) and the frequency analysis module (18) can be implemented by programming in a computer or in a single-chip microcomputer.

[0039] Cross-correlation analysis can use fast Fourier transform to perform cross-correlation analysis on the vibration signals of the dual vibration probes, or directly calculate the correlation coefficient of the dual vibration probe signals to obtain the distribution of the correlation coefficient with the transit time. The transit time corresponding to the maximum correlation coefficient is the time it takes for the liquid bomb or gas bomb to pass through the two vibration probes. The time it takes for the gas bomb or liquid bomb to pass through the two vibration probes is the same. The moving speed of the gas bomb can be calculated based on the installation spacing of the dual vibration probes and the obtained transit time. The calculation formula is as follows:

[0040]

[0041] In formula (1), L is the installation distance between the two vibration probes, τ is the transit time corresponding to the maximum correlation coefficient, and v t It is the moving speed of the gas bullet, which is also the moving speed of the liquid bullet.

[0042] Frequency analysis is to analyze and count the vibration waveforms of the dual vibration probes. The vibration frequency in the vibration signal can be obtained by combining the counting time. This frequency is the fluctuation frequency of the slug flow. The fluctuation frequency can also be obtained by performing Fourier transform on the vibration signal, which is represented by f.

[0043] Secondly, in the flow calculation module (19), the gas phase flow rate and liquid phase flow rate of the slug flow are calculated based on the two parameters of the moving speed of the gas bomb and the fluctuation frequency of the slug flow.

[0044] Specifically, according to the two-phase flow theory, the functional relationship between the moving speed of the gas bomb and the mixed flow velocity of the two-phase flow can be expressed as:

[0045]

[0046] In formula (2), v m is the mixed velocity of the two-phase flow, g is the gravitational acceleration (g = 9.8 m / s 2 ), D is the inner diameter of the pipe (22), and C1 and C2 are coefficients related to the pipe inclination, fluid properties, etc. For a gas-liquid two-phase flow with known fluid properties and pipe inclination, C1 and C2 are definite values, which can be determined based on two-phase flow theory or by experimental determination.

[0047] According to the functional relationship between the fluctuation frequency of the slug flow and the mixed flow rate and the volume liquid content, the volume liquid content of the gas-liquid two phases can be calculated. The functional relationship between the fluctuation frequency (expressed as f) and the mixed flow rate and the volume liquid content is:

[0048]

[0049] In formula (3), β L is the volume liquid content, is an undetermined function related to the volume liquid content; for gas-liquid two-phase flow with known fluid properties and pipeline inclination, It can be determined based on two-phase flow theory or through experimental measurement.

[0050] The product of the mixed flow velocity and the cross-sectional area of ​​the pipe is the total volume flow rate of the gas and liquid phases. Knowing the volume liquid content and the total volume flow rate, the product of the volume liquid content and the total volume flow rate is the volume flow rate of the liquid phase; further, the volume flow rate of the gas phase can be obtained by subtracting the volume flow rate of the liquid phase from the total volume flow rate of the gas and liquid phases; thus, the flow measurement of the gas and liquid phases is completed. The volume flow rates of the liquid phase and the gas phase are calculated as follows:

[0051] Q L =v m Aβ L (4)

[0052] Q G =v m AQ L (5)

[0053] In formula (4) and formula (5), A is the cross-sectional area of ​​the pipe, Q is L and Q G are the volume flow rate of the liquid phase and the volume flow rate of the gas phase, respectively.

[0054] The cross section of the vibrating needle (1) can be circular, elliptical or other shapes, and can be solid or a hollow tube with both ends closed; the cross section of the vibrating needle along the length direction can be a uniform cross section or a non-uniform cross section. The vibrating needle can be made of metal, plastic, composite material or other materials.

[0055] (II) Calculation example

[0056] From the above, it can be seen that the above measuring device measures the flow rate of gas-liquid two-phase in the pipeline. The gas-liquid two-phase slug flow of air and water in the pipeline (22) flows in a vertical pipe, and the flow conditions are normal temperature and pressure; the inner diameter of the pipeline is 0.025 meters, that is, D = 0.025 meters in formula (2) and formula (3).

[0057] The dual vibration probes (downstream vibration probe (20) and upstream vibration probe (21)) are vertically installed on the pipeline (22) at a spacing of 12 times the pipe diameter. The installation spacing of the dual probes is: L = 0.025 × 12 = 0.3 meters, that is, L = 0.3 meters in formula (1).

[0058] The end of one end of the vibrating needle (1) contacts the plug flow in the pipeline (22), and the gas bomb (24) and liquid bomb (23) flowing alternately respectively hit the vibrating needle (1), causing the vibrating needle to vibrate. The vibration signal of the vibrating needle (1) is transmitted to the visual mark (13) through the magnetic force of the permanent magnet (12), so that the visual mark (13) vibrates along with the vibrating needle (1), and the vibration of the visual mark (13) reflects the fluctuation of the plug flow. The high-speed camera (15) captures the dynamic image signal or video signal of the visual mark (13) of the dual vibration probes (20, 21), and the visual mark in the dynamic image is visually analyzed in the vibration signal extraction module (16) to extract the vibration signal. In this embodiment, the schematic diagram of the vibration signal extracted from the visual mark (13) of the downstream vibration probe (20) and the upstream vibration probe (21) is shown in the attached figure. Figure 2 .

[0059] In the cross-correlation analysis module (17), the vibration signal of the dual vibration probe (see Appendix) is analyzed by fast Fourier transform. Figure 2 ) to perform cross-correlation analysis, and the distribution of the correlation coefficient with the transit time is shown in the attached Figure 3 , where the maximum phase relationship is 0.89, and the corresponding transit time is 0.24 seconds, that is, τ = 0.24 seconds in formula (1), and the 0.24 seconds is the time for the liquid bomb or gas bomb to pass through the double vibration probe.

[0060] Divide the installation distance of the dual vibration probes by the obtained transit time, and the moving speed of the gas bomb can be obtained from formula (2) to be 1.25 m / s, which can be calculated by referring to the following formula:

[0061]

[0062] For a vertical pipe with a diameter of D = 0.025 m and the physical properties of air and water at normal temperature and pressure, according to the two-phase flow theory, the coefficient C1 in formula (2) is 1.2, the coefficient C2 is 0.35, and the gravitational acceleration g is 9.8 m / s 2 Therefore, the relationship between the moving speed of the air bomb and the mixing velocity of the two-phase flow can be expressed as:

[0063]

[0064] According to this relationship, when v t =1.25 m / s, the mixed velocity v of the two-phase flow can be obtained m =0.90 m / s.

[0065] The vibration frequency of the dual vibration probe (20, 21) signal is analyzed in the vibration signal frequency analysis module (18), and the fluctuation frequency of the slug flow is obtained to be 3.0 Hz. For the above-mentioned air-water slug flow in the vertical pipe, according to formula (3) and experimental measurement results, the specific relationship between the vibration frequency and the mixed flow velocity and the volume liquid content is obtained as follows:

[0066]

[0067] Since the mixing flow rate v m =0.90m / s, pipe diameter D = 0.025m, gravitational acceleration g = 9.8m / s 2 , the frequency f is 3.0 Hz, so the volume liquid content β is calculated L =3.0 / 6.6=0.45.

[0068] In the gas phase and liquid phase flow calculation module (19), the pipe cross-sectional area is calculated to be A=0.00049 square meters from the pipe diameter D=0.025 meters; further, from formula (4), it can be obtained that:

[0069]

[0070] From formula (5), we can get:

[0071]

[0072] (III) Summary

[0073] From the above implementation methods, it can be seen that the measuring device of this case uses the fluctuation characteristics of the slug flow to implement the measurement of the two-phase flow rate. Therefore, it will not fail due to the fluctuation characteristics of the slug flow, and does not require auxiliary equipment such as a gas-liquid separator. It can be installed online on the pipeline to measure the dynamic flow of the gas phase and the liquid phase in the slug flow in real time. The measuring device of this case is not affected by the viscosity of the liquid phase on the probe signal, nor is it restricted by whether the liquid phase is conductive or light-conductive. It is suitable for both water-gas two-phase flow and oil-gas two-phase flow, especially the two-phase slug flow of natural gas and oil in petroleum engineering, and the two-phase slug flow of gas and organic working fluid in chemical engineering. The device is conducive to engineering and technical personnel to use the fluctuation characteristics of the slug flow to measure the dynamic flow of the gas phase and the liquid phase in the slug flow online under the fluctuating working conditions of the slug flow, and provide dynamic flow data of the gas phase and the liquid phase for the implementation of process control, metering and transfer, and optimization of production parameters.

[0074] Based on the above embodiments, those skilled in the art can implement a method for measuring flow rate related to gas-liquid two-phase slug flow based on vibration vision, including: making a visual marker generate a vibration corresponding to the fluctuation of the gas-liquid two-phase slug flow, and then obtaining a vibration signal of the visual marker based on a dynamic image or video of the vibration of the visual marker; obtaining vibration signals of the visual marker corresponding to two locations upstream and downstream of the gas-liquid two-phase slug flow, performing cross-correlation analysis and frequency analysis, and realizing online measurement of the dynamic flow rate of the gas-liquid two-phase.

[0075] Through the description of the above implementation methods, those skilled in the art can clearly understand that the method part involved in the present disclosure can be implemented by means of software plus necessary general hardware, and of course can also be implemented by special hardware including special integrated circuits, special CPUs, special memories, special components, etc. In general, all functions completed by computer programs can be easily implemented by corresponding hardware, and the specific hardware structures used to implement the same function can also be various, such as analog circuits, digital circuits or special circuits, etc. However, for the present disclosure, software program implementation is a better implementation method in most cases.

[0076] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A gas-liquid two-phase slug flow related flow measurement device based on vibration vision, characterized in that: The measuring device includes a double vibration probe, a signal acquisition module, and an analysis module; Each vibration probe is fixed on the pipe of the slug flow by a base, and a vibrating needle is fixed in the base by a seal. One end of the vibrating needle contacts the slug flow to detect the fluctuation of the gas-liquid two-phase slug flow. The other end of the vibrating needle has a magnet, which faces the magnetic visual mark. There is a magnetic force between the magnet and the visual mark, and the magnetic force makes the visual mark and the vibrating needle vibrate synchronously. a signal acquisition module configured to acquire a vibration signal of the visual marker based on a dynamic image or video of the visual marker vibration; The analysis module is configured to utilize the vibration signals of the visual markers corresponding to the dual vibration probes located upstream and downstream of the slug flow to achieve online measurement of the dynamic flow rates of the gas-liquid two phases.

2. The device according to claim 1, characterized in that: The sealing member comprises a sealing ring, a sealing ring gland and a sealing flange. The vibrating needle passes through the sealing ring, the sealing ring gland and the sealing flange. The sealing ring is pressed against the sealing flange by tightening the sealing ring gland. The vibrating needle contacts the sealing ring but not the sealing gland and the sealing flange.

3. The device according to claim 1, characterized in that: One end of the base has two sections of internal threads of different sizes, the larger internal thread is used to connect with the pipe, and the smaller internal thread is used to connect with the external thread of the seal; The other end of the base is provided with an external thread which is connected with the internal thread of the cap. The cap is provided with a transparent visual mark box, and the transparent visual mark box has a visual mark inside.

4. The device according to claim 3, characterized in that The cap is made of low magnetic permeability material.

5. The device according to claim 3, characterized in that: One end of the visual mark is fixed on the inner wall of the transparent visual mark box, and the other end is suspended. The suspended end is closer to the magnet than the fixed end. The suspended end is magnetic and has color characteristics and / or shape characteristics for identification.

6. The device according to claim 1, characterized in that The visual markers are filaments or capillaries.

7. The device according to claim 1, characterized in that: The device also includes a camera for acquiring a dynamic image or video of the vibration of the visual marker, and performing visual analysis on the dynamic image or video of the vibration of the visual marker to obtain a vibration signal of the visual marker.

8. The device according to claim 1, characterized in that The processing of the analysis module includes: Based on the vibration signals of the visual markers corresponding to the dual vibration probes located upstream and downstream of the slug flow, the distribution of the correlation coefficient with the transit time is obtained through cross-correlation analysis. The transit time corresponding to the maximum correlation coefficient is taken as the time when the gas bomb passes through the dual vibration probes. The moving speed of the gas bomb is obtained by dividing the distance between the dual vibration probes upstream and downstream of the slug flow by the transit time. The functional relationship between the moving speed of the gas bomb and the mixed flow velocity of the two-phase flow is used to calculate the mixed flow velocity of the two-phase flow, which is then multiplied by the cross-sectional area of ​​the pipe to obtain the total volume flow rate of the gas-liquid two-phases. Based on the vibration signals of the visual markers corresponding to the dual vibration probes, the fluctuation frequency of the slug flow is obtained through frequency analysis; The volume liquid content of the gas-liquid two phases is calculated by using the functional relationship between the fluctuation frequency, the mixed flow rate and the volume liquid content; The calculated volume liquid content of the gas-liquid two-phase is multiplied by the total volume flow rate of the gas-liquid two-phase to obtain the volume flow rate of the liquid phase, and the volume flow rate of the liquid phase is subtracted from the total volume flow rate of the gas-liquid two-phase to obtain the volume flow rate of the gas phase.

9. The device according to claim 1, characterized in that: The distance between the dual vibration probes upstream and downstream of the slug flow is 2 to 20 times the pipe diameter.

10. A method for measuring flow rate of gas-liquid two-phase slug flow based on vibration vision, characterized in that: The method comprises: The visual marker is caused to generate vibrations corresponding to the fluctuations of the gas-liquid two-phase slug flow, and then a vibration signal of the visual marker is obtained based on a dynamic image or video of the vibration of the visual marker; The vibration signals of the corresponding visual markers at the upstream and downstream of the gas-liquid two-phase slug flow are obtained, and cross-correlation analysis and frequency analysis are performed to achieve online measurement of the dynamic flow rate of the gas-liquid two-phase.

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