Doppler flowmeter traceability device and method based on gas-liquid two-phase flow

Abstract

The invention discloses a Doppler flowmeter traceability device and method based on gas-liquid two-phase flow, and the device comprises an air pump and an air compressor which are used as power sources of a gas phase and a liquid phase, the pressure in a gas phase pipeline is adjusted through a pressure reducing valve, a pressure tracking algorithm is adopted to enable a liquid phase pipeline to track the pressure of the gas phase pipeline, and the pressures of the two pipelines are kept consistent; the control difficulty caused by different pressure is avoided; the flow of the gas-liquid two-phase pipeline is controlled by PID and is combined with a manual control valve, two-phase control from small flow to large flow is achieved, the gas-liquid two-phase pipeline enables the liquid phase to have fixed bubbles through a Y-shaped manifold, and the gas phase and the liquid phase are formed. A Doppler flowmeter signal generating head is installed on the reducing pipe section, and the measured flow is compared with the standard flow on the gas-liquid two-phase-splitting pipeline to be traced. The Doppler flowmeter can be traced, and the Doppler flowmeter can be conveniently applied to production and life.

Description

Technical Field

[0001] This invention belongs to the field of fluid metering, specifically relating to a Doppler flowmeter traceability device and method based on gas-liquid two-phase flow. Background Technology

[0002] Currently, ultrasonic flow meters are widely used in various fields such as oil and gas, energy and chemical industry in my country. They have become widely popular due to their advantages such as having no moving parts, low pressure loss and no pipeline obstruction.

[0003] Ultrasonic flow meters, as non-contact flow meters, include methods such as noise measurement, Doppler flow measurement, correlation measurement, time-of-flight measurement, and vortex flow measurement. Time-of-flight and Doppler flow measurement are currently the two most commonly used methods on the market. However, due to their different measurement principles, the applicable ranges of ultrasonic flow meters based on these two methods differ. Currently, time-of-flight ultrasonic flow meters are favored by many engineering projects because of their ease of traceability. However, they cannot function properly in conditions containing air bubbles or a large number of solid particles, leading to inaccurate measurements. In many situations, such as oil, sewage, pulp, and slurry, air bubbles or solid particles are often present in the pipelines. In these cases, Doppler ultrasonic flow meters are more suitable. However, due to the lack of traceability technology for Doppler ultrasonic flow meters, it is currently impossible to provide complete traceability conditions and guarantee their accuracy. Therefore, in most cases, Doppler flow meters are still not considered, and time-of-flight flow meters or other flow meters continue to be used as the metering instrument choice. This hinders the widespread adoption of Doppler flow meters, causing many companies to abandon their production.

[0004] Doppler flow meters require the presence of air bubbles or solid particles in the medium. Traceability of Doppler flow meters necessitates the addition of a measured amount of air or solid particles to the traceable medium, while simultaneously controlling the flow within the pipeline. Doppler flow meters utilize the Doppler effect, measuring flow velocity by the phase difference in the liquid. The movement of air bubbles and solid particles generates a frequency shift in the ultrasonic signal, creating a phase difference, which is then used to measure the current flow rate. Traceability of the Doppler flow meter signal can be achieved by using a measured amount of air bubbles and controlling the liquid flow rate.

[0005] To ensure the accuracy of Doppler flow meters, the primary method currently used is traceability through standard flow calibration devices. This involves tracing the standard flow device within the manufacturing plant against the local metrology department, which then traces it back to its superior metrology department. Therefore, as a metering instrument, Doppler flow meters must be traceable to guarantee accuracy. However, due to the characteristics of flow measurement, the traceability process using standard flow calibration devices is time-consuming and energy-intensive, resulting in significant waste. Furthermore, during use, varying operating conditions can affect the flow meter's measurement accuracy, leading to varying degrees of reduction.

[0006] Therefore, there is an urgent need to develop a technology that can reduce the time spent on flow meter traceability, reduce energy consumption, and ensure that the measurement accuracy does not decrease due to changes in the working environment during use.

[0007] Chinese invention patent CN113916308B discloses a multi-well two-phase flow metering skid and its metering method, including a first production pipeline, a second production pipeline, and several wellhead connecting pipelines. Each wellhead connecting pipeline is connected to the second production pipeline via a second production connecting pipeline. Each second production connecting pipeline is equipped with a second control valve. Each second production connecting pipeline is also equipped with a first transition pipeline and a second transition pipeline. The first and second transition pipelines are respectively equipped with a first control valve and a third control valve. The first and second transition pipelines are connected to the first production connecting pipeline. A two-phase flow meter is installed on the first production connecting pipeline at a position between the first and second transition pipelines and the first production connecting pipeline. A fourth control valve is installed on the first production connecting pipeline. This invention can perform two-phase flow metering and can perform online self-calibration for each two-phase flow meter.

[0008] Chinese invention patent CN111504407B discloses an online measurement method for gas-liquid two-phase flow in a producing gas reservoir well. The method includes: Step 1: Assuming the gas and liquid phases flow at the same velocity and are uniformly mixed, maintaining thermal equilibrium, the mixing density of the two phases is derived; the formula for calculating the homogeneous gas-liquid two-phase flow is given. Step 2: Based on the relationship between the gas-liquid two-phase flow coefficient K and the gas holdup parameter, and the two-phase flow formula, the functional relationship between the gas-liquid two-phase flow coefficient K and the gas-liquid two-phase mass flow rate W is determined. This invention enables simultaneous, interference-free real-time measurement of two-phase fluids flowing within a pipe. Compared with existing measurement methods, it overcomes the shortcomings of traditional methods, improves measurement accuracy, enhances the signal feedback mechanism, and truly achieves online measurement of gas-liquid two-phase flow.

[0009] The above-mentioned solutions all provide a method for measuring the flow rate of two-phase flow by separately measuring the gas and liquid two-phase flows. Based on this, the applicant has developed a Doppler flowmeter traceability device and method based on gas-liquid two-phase flow, which can reduce the time consumed in flowmeter traceability, reduce energy consumption, and ensure that the measurement accuracy does not decrease due to changes in the operating environment during use. Summary of the Invention

[0010] To address the lack of traceability technology for Doppler flow meters, this invention proposes a traceability method for Doppler flow meters. This method controls the flow rates of liquid and gas within a pipeline, creating bubbles for traceability. It also incorporates a two-phase confluence pipeline design. By controlling the flow rates of the gas-liquid two-phase flow within the pipeline, the flow rate displayed by the Doppler flow meter changes, enabling traceability during flow comparison. This fills the current market gap for traceable Doppler flow meters, allowing them to better participate in production and development.

[0011] Against this backdrop, one objective of the present invention is to address the lack of traceability technology for Doppler flowmeters by proposing a traceability device for Doppler flowmeters, which allows for quick and convenient installation of the Doppler flowmeter on a variable diameter pipe section for calibration and traceability.

[0012] Another objective of this invention is to provide a traceability method for Doppler flowmeters, which forms a stable two-phase flow state by controlling the liquid flow rate and gas flow rate in the first pipe section and the second pipe section for traceability of Doppler flowmeters.

[0013] The technical problem to be solved by the present invention is to provide a Doppler flowmeter traceability device based on gas-liquid two-phase flow, which addresses the shortcomings of the existing technology.

[0014] The technical problem to be solved by the present invention is to provide a Doppler flowmeter traceability method based on gas-liquid two-phase flow, which addresses the shortcomings of the existing technology.

[0015] To achieve the objectives of this invention, the following technical solution is adopted:

[0016] A Doppler flowmeter traceability device based on gas-liquid two-phase flow includes a pipe section comprising: a first pipe section for gas flow only, on which a first pressure transmitter, a first temperature transmitter, and a rotary flowmeter are installed; the first pressure transmitter and the temperature transmitter are adapted to monitor the pressure and temperature signals of the first pipe section in real time, respectively; a second pipe section for liquid flow only, on which three pneumatic switching valves are installed: a first pneumatic switching valve, a second pneumatic switching valve, and a third pneumatic switching valve; the three pneumatic switching valves divide the flow path of the second pipe section into a first flow path, a second flow path, and a third flow path; a first electromagnetic flowmeter, a second electromagnetic flowmeter, and a third electromagnetic flowmeter are respectively installed on the first, second, and third flow paths; the first flow path is a high-flow-rate regulating path, and the second and third flow paths are low-flow-rate regulating paths; the diameter of the first flow path is larger than that of the second or third flow path; and a manifold section having a first inlet... The system includes a first inlet, a second inlet, and an outlet, with the first and second inlets in fluid communication with the output ends of the first and second pipe sections, respectively; a variable diameter pipe section, adapted to install a Doppler flow meter to be traced, and in fluid communication with the outlet of the manifold section; an observation window, comprising a first transparent window located upstream of the variable diameter pipe section and a second transparent window located downstream of the variable diameter pipe section, the first transparent window being adapted to observe the fluid flow state before entering the variable diameter pipe section, and the second transparent window being adapted to observe the fluid flow state out of the variable diameter pipe section; and a control system, adapted to adjust the pressure in the first and second pipe sections to keep them consistent, and adapted to control the fluid flow rate flowing from the first and second pipe sections into the manifold section respectively. After the fluid flow state in the variable diameter pipe section after converging in the manifold section reaches a stable state, the traceability of the Doppler flow meter is achieved by comparing the sum of the flow rate readings in the first and second pipe sections with the flow rate reading of the Doppler flow meter.

[0017] In one embodiment, the control system acquires the pressure signal of the first pipe section through a pressure tracking algorithm, and adjusts the working pressure of the second pipe section through a frequency converter so that the pressure in the first pipe section and the second pipe section remains consistent.

[0018] In one embodiment, a second pressure transmitter is provided on the second pipe section, the second pressure transmitter being adapted to monitor the pressure signal and temperature signal of the second pipe section in real time.

[0019] In one embodiment, an air compressor, a gas pressure stabilizing tank, a pressure reducing valve, and a filter are sequentially connected upstream of the first pipe section, and a first manual regulating valve and a first electric regulating valve are sequentially connected downstream of the first pipe section. The first electric regulating valve is suitable for coarse flow adjustment, and the first manual regulating valve is suitable for fine flow adjustment.

[0020] In one embodiment, a one-way valve is further included between the first manually adjustable valve and the first electrically adjustable valve, the one-way valve being adapted to prevent backflow due to pressure imbalance between the first pipe section and the second pipe section.

[0021] In one embodiment, a water pump and a liquid flow stabilizer are sequentially connected upstream of the second pipe section, which are suitable for drawing liquid from the water tank into the pipe section, and a second electric regulating valve is connected downstream of the first flow pipe.

[0022] In one embodiment, a second manual regulating valve and a third manual regulating valve are respectively installed in the second flow pipeline and the third flow pipeline. After the second flow pipeline and the third flow pipeline merge downstream, a third electric regulating valve is connected. The third electric regulating valve is suitable for coarse flow adjustment, and the second manual regulating valve and the third manual regulating valve are suitable for fine flow adjustment.

[0023] In one embodiment, the rotary flow meter is installed downstream of the first manual regulating valve; the first electromagnetic flow meter, the second electromagnetic flow meter, and the third electromagnetic flow meter are respectively installed downstream of the first pneumatic switching valve, the second manual regulating valve, and the third manual regulating valve.

[0024] In one embodiment, the high-flow regulating pipe has a diameter of DN25 and can control a flow rate range of 500 to 10000 L / h.

[0025] In one embodiment, the small flow regulating pipe has a diameter of DN5 and DN2.5, and the controllable flow regulation range is 70~700L / h and 18~180L / h, respectively.

[0026] In one embodiment, the control system uses a PID control algorithm to collect the gas flow signal fed back by the rotary flow meter as a feedback value to change the valve opening of the first electric regulating valve, thereby controlling the gas flow in the first pipe section.

[0027] In one embodiment, the liquid flow signal fed back by the first electromagnetic flowmeter is collected as a feedback value to change the valve opening of the second electric regulating valve, thereby controlling the liquid flow in the first flow pipeline.

[0028] In one embodiment, a three-way valve is provided downstream of the variable diameter pipe section. The three-way valve is adjusted to flow upward, thereby creating back pressure within the pipe section.

[0029] In one embodiment, the three-way valve is connected upward to a third transparent window, which is adapted to observe the vertical flow state of the fluid flowing out of the variable diameter pipe section.

[0030] In one embodiment, the manifold section is a Y-shaped transparent circular tube, and the included angle of the Y-shape is 85°.

[0031] A Doppler flowmeter traceability method based on gas-liquid two-phase flow includes a pipe section and a control system. The pipe section includes: a first pipe section for gas flow only, equipped with a first pressure transmitter and a temperature transmitter, which are respectively adapted to monitor the pressure and temperature signals of the first pipe section in real time. A first manual regulating valve and a first electric regulating valve are sequentially connected downstream of the first pipe section, and a rotary flowmeter is installed downstream of the first manual regulating valve; and a second pipe section for liquid flow only, equipped with three pneumatic switching valves: a first pneumatic switching valve, a second pneumatic switching valve, and a third pneumatic switching valve. These three pneumatic switching valves divide the flow path of the second pipe section into a first flow path, a second flow path, and a third flow path. The diameter of the first flow path is larger than that of the second or third flow path. The first flow path is a high-flow regulating path, while the second and third flow paths are low-flow regulating paths. A second electrically controlled regulating valve is connected downstream of the pipeline. A second manually controlled regulating valve and a third manually controlled regulating valve are also installed in the second and third flow pipelines, respectively. The second and third flow pipelines merge downstream and are connected to a third electrically controlled regulating valve. A first electromagnetic flowmeter, a second electromagnetic flowmeter, and a third electromagnetic flowmeter are installed in the first, second, and third flow pipelines, respectively. A manifold section has a first inlet, a second inlet, and an outlet. The first and second inlets are fluidly connected to the output ends of the first and second pipe sections, respectively. A variable diameter pipe section is adapted to install the Doppler flowmeter to be traced and is fluidly connected to the outlet of the manifold section. An observation window includes a first transparent window located upstream of the variable diameter pipe section and a second transparent window located downstream of the variable diameter pipe section. The first transparent window is adapted to observe the fluid flow state before entering the variable diameter pipe section, and the second transparent window is adapted to observe the fluid flow state out of the variable diameter pipe section.

[0032] The steps of the Doppler flowmeter tracing method based on gas-liquid two-phase flow include:

[0033] S1: Set the required gas flow rate of the first pipe section and the liquid flow rate of the second pipe section on the computer respectively;

[0034] S2: Supply fluid to the first pipe section and the second pipe section respectively according to preset values;

[0035] S3: The control system uses a pressure tracking algorithm to ensure that the pressure in the first pipe section and the second pipe section remains consistent;

[0036] S4: The control system uses a PID control algorithm to control the first electric regulating valve to regulate the flow of the first pipe section and to control the second electric regulating valve to regulate the flow of the second pipe section.

[0037] S5: Use the manifold to combine the fluids flowing out of the first pipe section and the second pipe section, so that the gas-liquid two-phase flow merges, and observe the observation window until the fluid flow in the variable diameter pipe section is stable and there are uniform bubbles.

[0038] S6: Install the Doppler flow meter to the variable diameter pipe section, apply coupling agent to the surface of the variable diameter pipe section and the signal generating device of the Doppler flow meter, and fix the generating device to the outer wall of the variable diameter pipe section;

[0039] S7: Compare the displayed value of the Doppler flow meter with the sum of the fluid flow rates of the first pipe section and the second pipe section to achieve traceability of the Doppler flow meter.

[0040] In one embodiment, the pressure tracking algorithm in step S3 specifically includes: real-time monitoring of the pressure and temperature signals fed back by the first pressure transmitter and the temperature transmitter in the first pipe section; converting the pressure signal into a corresponding control signal for the frequency converter; the computer adjusting the working pressure in the second pipe section through the frequency converter; and maintaining equal pressure in the first pipe section and the second pipe section through feedback from the second pressure transmitter and the temperature transmitter in the second pipe section, so as to prevent uneven pressure when the first pipe section and the second pipe section merge through the manifold section.

[0041] In one embodiment, the PID control algorithm in step S4 specifically includes: collecting the gas flow signal fed back by the rotary flow meter as a feedback value to change the valve opening of the first electric regulating valve, thereby controlling the gas flow in the first pipe section; collecting the liquid flow signal fed back by the first electromagnetic flow meter as a feedback value to change the valve opening of the second electric regulating valve, thereby controlling the liquid flow in the first flow pipeline.

[0042] In one embodiment, prior to step S5, the method further includes: using the third electric regulating valve to perform coarse flow adjustment on the second pipeline.

[0043] In one embodiment, before step S5, the method further includes: manually and precisely adjusting the small flow regulating pipeline using the second manual regulating valve and the third manual regulating valve: after the second pneumatic switch valve is opened, the flow rate of the second flow pipeline is controlled by the second manual regulating valve, and the flow rate is indicated by the second electromagnetic flow meter; after the third pneumatic switch valve is opened, the flow rate of the third flow pipeline is controlled by the third manual regulating valve, and the flow rate is indicated by the third electromagnetic flow meter.

[0044] In one embodiment, before step S5, the method further includes: using the first manual regulating valve to perform coarse flow adjustment on the first pipeline.

[0045] In one embodiment, before step S5, the method further includes: after the gas-liquid two-phase flow enters the manifold section and merges, monitoring in real time through the flow state in the first transparent window whether there are bubble flows and flow stability in the medium that can be used for traceability during the traceability process.

[0046] In one embodiment, before step S5, the method further includes: a three-way valve is provided downstream of the variable diameter pipe section, the three-way valve is adjusted to flow upward, so that back pressure is formed in the pipe section to prevent the liquid phase from not filling the pipe when the liquid flow rate is relatively small; the gas-liquid two-phase flow state after the variable diameter pipe section is observed through the second transparent window.

[0047] In one embodiment, before step S5, the method further includes: the three-way valve is connected to a third transparent window, through which the flow state of the vertically flowing fluid exiting the variable diameter pipe section is observed to see if it is stable.

[0048] In one embodiment, before step S5, the method further includes: changing the diameter of the variable diameter pipe section and installing the Doppler flowmeter to be traced on the variable diameter pipe section for multiple traceability measurements.

[0049] Compared with the prior art, the beneficial effects of the present invention are:

[0050] On the one hand, the pressure tracking algorithm is used to keep the working pressure of the gas-liquid fluid in the first and second pipe sections the same, which facilitates mixing.

[0051] On the one hand, the PID control algorithm is used to precisely regulate the fluid flow in the pipe section by adjusting the opening and closing of the electric regulating valve, which is accurate and convenient;

[0052] On the one hand, by adopting a combination of manual adjustment and PID control, the combined flow rate and the split flow rate of the gas-liquid two-phase flow in the pipeline are supplemented and adjusted, thereby improving the convenience and control efficiency.

[0053] On the one hand, the use of 85° Y-shaped manifold sections eliminates the traditional T-shaped manifold, avoiding turbulent flow such as eddies and improving the stability of the fluid after mixing.

[0054] On the one hand, observation windows are set at key nodes of each mixing flow to observe the mixing state of the two-phase flow in real time, so that the merging medium is a controllable flow medium containing air bubbles, which is convenient for calibrating the standard flow rate.

[0055] On the one hand, by constructing a standard gas-liquid two-phase flow and controlling the flow with different gas contents, the Doppler flowmeter can be traced, which ensures the reliability of the Doppler flowmeter in production and daily life, provides a reliable solution for the traceability of the Doppler flowmeter, and promotes the development and wider application of the Doppler flowmeter. Attached Figure Description

[0056] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 This is a structural diagram of a specific embodiment of the present invention;

[0058] Figure 2 This is a simplified structural diagram of a specific embodiment of the present invention;

[0059] Figure 3 This is a schematic diagram of a Y-shaped manifold section according to a specific embodiment of the present invention;

[0060] Figure 4 This is a schematic diagram of a variable diameter pipe section with a Doppler flow meter installed according to a specific embodiment of the present invention;

[0061] Figure 5 This is a flowchart of a tracing method according to a specific embodiment of the present invention.

[0062] Figure label:

[0063] 1. Air compressor; 2. Gas pressure stabilizing tank; 3. Pressure reducing valve; 4. Filter; 5. First pressure transmitter; 6. Temperature transmitter; 7. First manual regulating valve; 8. Rotary wheel flow meter; 9. Check valve; 10. First electric regulating valve; 11. Water pump; 12. Liquid flow stabilizing tank; 13. Second pressure transmitter; 14. Frequency converter; 15. First pneumatic switching valve; 16. Second pneumatic switching valve; 17. Third pneumatic switching valve; 18. Second manual regulating valve; 19. Third manual regulating valve; 20. First electric... 21. Magnetic flowmeter; 22. Second electromagnetic flowmeter; 23. Third electromagnetic flowmeter; 24. Third electric regulating valve; 25. Second electric regulating valve; 26. Y-type manifold section; 27. First transparent window; 28. Variable diameter pipe section; 29. ​​Second transparent window; 30. Three-way valve; 31. Third transparent window; 32. Water tank; 33. Computer; 34. First inlet; 35. Second inlet; 36. Outlet; 37. First Doppler flowmeter signal generator; 38. Second Doppler flowmeter signal generator. Detailed Implementation

[0064] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0066] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. The terms "upper," "lower," "top," "bottom," "front," "rear," "inner," and "outer," etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and not a requirement that the invention must be constructed and operated in a specific orientation, and should not be construed as limiting the invention. The terms "installed," "set," "equipped with," "connected," "linked," and "sleeved" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] In this invention, for ease of understanding, the side closer to the operator's grip is defined as the proximal end, and the side farther from the operator's grip is defined as the distal end. The water rinsing operation on the object's surface is performed at the distal end. The area above the drawing is defined as the upper part, and the area below the drawing is defined as the lower part. The direction outward from the drawing is defined as the left side, and the direction inward from the drawing is defined as the right side. The above definitions are for illustrative purposes only and should not be construed as limiting the invention.

[0068] Please see Figure 1-4 As shown, a Doppler flowmeter traceability device based on gas-liquid two-phase control is presented.

[0069] A Doppler flowmeter traceability device based on gas-liquid two-phase flow includes multiple pipe sections. The multiple pipe sections are a first pipe section, a second pipe section, a manifold section, and a variable diameter pipe section.

[0070] The first pipe section, used solely for gas flow, is the gas phase pipe section. Upstream of the first pipe section are sequentially connected an air compressor 1 (suitable for drawing in atmospheric air), a gas pressure stabilizing tank 2, a pressure reducing valve 3, and a filter 4. Downstream of the first pipe section are sequentially connected a first manual regulating valve 7 and a first electric regulating valve 10. The first electric regulating valve 7 is suitable for coarse flow adjustment, and the first manual regulating valve 10 is suitable for fine flow adjustment. A one-way valve 9 is also included, installed between the first manual regulating valve 7 and the first electric regulating valve 10. The one-way valve 9 is suitable for preventing backflow caused by pressure imbalance between the first and second pipe sections. A rotary flow meter 8 is installed between the first manual regulating valve 7 and the one-way valve 9.

[0071] The second pipe section, used solely for liquid flow, is the liquid phase pipe section. Three pneumatic valves are installed on the second pipe section: a first pneumatic valve 17, a second pneumatic valve 18, and a third pneumatic valve 19. These three valves divide the flow path of the second pipe section into a first flow path, a second flow path, and a third flow path. Upstream of the second pipe section are a water pump 11 suitable for drawing liquid from a water tank into the pipe section and a liquid flow stabilizer 12.

[0072] A second electrically operated regulating valve 23 is connected downstream of the first flow pipeline. A second manually operated regulating valve 18 and a third manually operated regulating valve 19 are also installed in the second and third flow pipelines, respectively. After the second and third flow pipelines merge downstream, a third electrically operated regulating valve 24 is connected. The third electrically operated regulating valve 24 is suitable for coarse flow adjustment, while the second manually operated regulating valve 18 and the third manually operated regulating valve 19 are suitable for fine flow adjustment.

[0073] A first electromagnetic flowmeter 20, a second electromagnetic flowmeter 21, and a third electromagnetic flowmeter 22 are respectively installed on the first flow pipeline, the second flow pipeline, and the third flow pipeline. The first electromagnetic flowmeter 20, the second electromagnetic flowmeter 21, and the third electromagnetic flowmeter 22 are respectively installed downstream of the first pneumatic switch valve 15, the second manual regulating valve 18, and the third manual regulating valve 19.

[0074] Please combine Figure 1 As shown, the first flow path, second flow path, and third flow path of the first pipe section and the second pipe section are all horizontal flow paths. The first flow path is a high-flow-rate regulating pipe, while the second and third flow paths are low-flow-rate regulating pipes. The diameter of the first flow path is larger than that of the second or third flow path. Preferably, the high-flow-rate regulating pipe has a diameter of DN25 and a controllable flow range of 500–10000 L / h. The low-flow-rate regulating pipes have diameters of DN5 and DN2.5, with controllable flow ranges of 70–700 L / h and 18–180 L / h, respectively.

[0075] Please see Figure 3 As shown, the manifold section 25 has a first inlet 33, a second inlet 34, and an outlet 35. The first and second inlets are in fluid communication with the output ends of the first and second pipe sections, respectively. The manifold section is a Y-shaped transparent circular pipe with a Y-angle of 85°. The manifold section is horizontally positioned, and its orientation and flow direction are consistent with those of the first and second pipe sections.

[0076] Please see Figure 4As shown, the reducing pipe section 27 is suitable for installing the Doppler flow meter to be traced and is in fluid communication with the outlet of the manifold section 26. This pipe section is used to install the signal generating device 36 of the first Doppler flow meter and the signal generating device 37 of the second Doppler flow meter. Coupling agent is applied to the surface of the reducing pipe section 27 and the signal generating devices 36 and 37 of the first and second Doppler flow meters to enhance signal transmission and fix the generating devices to the pipe section. A three-way valve 29 is provided downstream of the reducing pipe section 27. Adjusting the three-way valve 29 to the upward flow direction creates back pressure in the pipeline, thereby preventing the liquid phase from filling the pipe when the liquid flow rate is relatively small.

[0077] The observation windows include a first transparent window 26 located upstream of the reducing pipe section 27, a second transparent window 28 located downstream of the reducing pipe section 27, and a third transparent window 30 connected upwards to the three-way valve 29. The first and second transparent windows 26 and 28 are horizontally aligned with the reducing pipe section 27. The first window is suitable for observing the fluid flow before entering the reducing pipe section, and the second window is suitable for observing the fluid flow out of the reducing pipe section. The third transparent window 30 is vertically positioned to facilitate observation of the vertical fluid flow out of the reducing pipe section 27. Once the flow stabilizes, the readings of the first electromagnetic flowmeter 20, the second electromagnetic flowmeter 21, or the third electromagnetic flowmeter 22 in the selected liquid phase pipeline are compared with the readings of the rotary flowmeter 8 and the measured values ​​of the Doppler flowmeter to trace the source of the Doppler flowmeter.

[0078] It also includes a control system, which is adapted to adjust the pressure in the first pipe section and the second pipe section to keep them consistent, and is adapted to control the flow rate of the fluid flowing into the manifold section from the first pipe section and the second pipe section respectively. After the flow state of the fluid flowing into the variable diameter pipe section 27 after being merged by the manifold section 25 reaches a stable state, the traceability of the Doppler flow meter is realized by comparing the sum of the flow rate indications in the first pipe section and the flow rate indications in the second pipe section with the flow rate indication of the Doppler flow meter.

[0079] The control system includes a first pressure transmitter 5, a temperature transmitter 6, a second pressure transmitter 13, and a frequency converter 14. The first pressure transmitter 5, temperature transmitter 6, and rotary flow meter 8 are installed on the first pipe section. The first pressure transmitter 5 and temperature transmitter 6 are respectively adapted to monitor the pressure and temperature signals of the first pipe section in real time. The second pressure transmitter 13 is installed on the second pipe section, adapted to monitor the pressure and temperature signals of the second pipe section in real time. The control system acquires the pressure signal of the first pipe section through a pressure tracking algorithm and adjusts the working pressure of the second pipe section through the frequency converter 14 to keep the pressure in the first and second pipe sections consistent.

[0080] The control system also includes a rotary flow meter 8, a first electromagnetic flow meter 20, a first electric regulating valve 10, and a second electric regulating valve 23. The control system uses a PID control algorithm to collect the gas flow signal fed back from the rotary flow meter 8 as feedback value to change the valve opening of the first electric regulating valve 10, thereby controlling the gas flow in the first pipe section. It also collects the liquid flow signal fed back from the first electromagnetic flow meter 20 as feedback value to change the valve opening of the second electric regulating valve 23, thereby controlling the liquid flow in the second pipe section.

[0081] Please see Figure 5 As shown, a Doppler flowmeter traceability method based on gas-liquid two-phase control is presented.

[0082] This includes setting the required gas-liquid two-phase flow rate on computer 32, starting water pump 11 and air compressor 1, wherein the gas phase pipeline has a diameter of DN25 and is connected to the atmosphere through the 0.7MPa air compressor 1, directly drawing atmospheric air into the gas pressure stabilizing pipe 2. After the gas pressure in the gas pressure stabilizing tank 2 stabilizes to 0.7MPa, the gas pressure in the gas pressure stabilizing tank is reduced to 0.2MPa through the pressure reducing valve 3.

[0083] Pressure reducing valve 3 is connected to filter 4. After passing through pressure reducing valve 3, the gas flow passes through filter 4 to filter particulate impurities in the air. Filter 4 is connected to the first manual regulating valve 7. Pressure transmitter 5 and temperature transmitter 6 are installed in the pipeline between them to monitor the pressure and temperature signals of the gas phase pipeline in real time.

[0084] After the computer 32 detects a change in the pressure in the gas phase pipeline, it uses a pressure tracking algorithm to convert the feedback pressure signal into a corresponding control signal for the frequency converter 14. The computer 32 is connected to the frequency converter 14, and the operating frequency of the frequency converter 14 is changed by changing the control current to adjust the pressure in the liquid pipeline to 0.2MPa, so that the pressure in the gas and liquid pipelines is equal. The pressure signal in the liquid phase pipeline is fed back through the second pressure transmitter 13 to prevent the control from being affected by uneven pressure when the two phases merge in the manifold.

[0085] The gas flow rate is coarsely adjusted using a first manual regulating valve 7, and then finely adjusted using a first electric regulating valve 10. During fine-tuning, a PID control algorithm is employed. A rotary flow meter 8 is connected after the first manual regulating valve 7. The gas flow rate signal fed back from the rotary flow meter 8 is collected by a computer 32 and used as the feedback value for the PID control algorithm. A one-way valve 9 and the electric regulating valve 10 are connected after the rotary flow meter 8. The opening degree of the electric regulating valve 1 is calculated and adjusted using the PID control of the computer 32, thereby changing the gas flow rate. The one-way valve 9 is placed after the rotary flow meter 8 to prevent pressure differences from causing the liquid phase pipeline to enter the gas phase pipeline through the Y-shaped manifold 25.

[0086] In the liquid phase pipeline, the water pump 11 is connected to the water tank 31. The water pump 11 draws the liquid into the liquid pipeline. Since the flow of the liquid drawn in by the water pump 11 is unstable, a liquid flow stabilizer 12 is connected after the water pump 11 to stabilize the liquid flow. After the liquid flow stabilizer 12, the liquid phase pipeline is divided into three flow pipelines by the first pneumatic switch valve 15, the second pneumatic switch valve 16 and the third pneumatic switch valve 17.

[0087] The pneumatic switch valve 15 controls a high-flow regulating pipeline with a diameter of DN25, and can control a flow rate range of 500~10000L / h. The second pneumatic switch valve 16 and the third pneumatic switch valve 17 control low-flow regulating pipelines with diameters of DN5 and DN2.5 respectively, and controllable flow rates of 70~700L / h and 18~180L / h respectively.

[0088] The flow control in the DN25 pipeline adopts the PID control algorithm. The second electric regulating valve 23 is controlled by the PID control algorithm. During this process, the computer 32 collects the feedback signal of the first electromagnetic flowmeter 20 as the feedback value of the PID control algorithm. The valve opening of the second electric regulating valve 23 is changed by the PID control algorithm to directly control the flow.

[0089] The same third electric regulating valve 24 is used in both the DN5 and DN2.5 pipelines. Because the electric regulating valve cannot control the flow rate precisely, the same third electric regulating valve 24 is used for coarse adjustment, and then a manual regulating valve is used for precise manual adjustment.

[0090] After the second pneumatic switch valve 16 is opened, the flow rate of the pipeline is controlled by the second manual regulating valve 18, and the flow rate is indicated by the second electromagnetic flowmeter 21. After the third pneumatic switch valve 17 is opened, the flow rate of the pipeline is controlled by the third manual regulating valve 19, and the flow rate is indicated by the third electromagnetic flowmeter 22. The two pipelines with small flow rates merge into one after passing through the second electromagnetic flowmeter 21 and the third electromagnetic flowmeter 22, and then enter the third electric regulating valve 24. The liquid phase pipeline merges into one DN25 pipeline after passing through the second electric regulating valve 23 and the third electric regulating valve 24.

[0091] The liquid phase pipeline is connected to the first inlet 33 of the Y-shaped manifold section 25 after the second electric regulating valve 23 and the third electric regulating valve 24 are combined into one. The first electric regulating valve 10 of the gas phase pipeline is connected to the second inlet 34 of the Y-shaped manifold section 25. The Y-shaped manifold section 25 has an included angle of 85° and a total length of 318 mm. After the gas and liquid phases merge in the Y-shaped manifold section 25, the flow state is observed in the first transparent window 26 to monitor in real time whether there are bubbles in the medium that can be used for traceability and the flow stability during the traceability process.

[0092] Since Doppler flow meters can measure in pipe sections of different diameters, it is necessary to change the diameter of the pipe section. The outlet 35 of the Y-type manifold section 25 is connected to the reducing pipe section 27, which is used to install the signal generating device 36 of the first Doppler flow meter and the signal generating device 37 of the second Doppler flow meter. Coupling agent is applied to the surface of the reducing pipe section 27 and the signal generating devices 36 and 37 of the first and second Doppler flow meters to enhance signal transmission and fix the generating devices to the pipe section.

[0093] The reducing pipe section 27 is connected to the three-way valve 29. Adjusting the three-way valve 29 to the upward flow direction creates back pressure within the pipe, preventing the liquid phase from filling the pipe when the liquid flow rate is relatively low. The second transparent window 28 and the third transparent window 30 are observed. The second transparent window 28 allows observation of the gas-liquid two-phase flow state after the reducing pipe section, while the third transparent window 30 allows observation of the vertical flow pattern after the reducing pipe section. Once the flow stabilizes, the readings of the first electromagnetic flowmeter 20, the second electromagnetic flowmeter 21, or the third electromagnetic flowmeter 22 in the selected liquid phase pipeline are compared with the readings of the rotary flowmeter 8 and the measured values ​​of the Doppler flowmeter to trace the source of the Doppler flowmeter.

[0094] Based on Euler's formula and the law of conservation of mass, we can obtain: Q v =Q 气 +Q 液

[0095] Where, is Q v Let Q be the volumetric flow rate under gas-liquid two-phase flow conditions. 气 Q is the volumetric flow rate under gas phase operating conditions. 液 This represents the volumetric flow rate under gas phase operating conditions.

[0096] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A Doppler flowmeter traceability device based on gas-liquid two-phase flow, comprising a pipe section, wherein the pipe section includes: The first pipe section is used only for gas flow. The first pipe section is equipped with a first pressure transmitter, a first temperature transmitter and a rotary flow meter. The first pressure transmitter and the first temperature transmitter are respectively adapted to monitor the pressure signal and temperature signal of the first pipe section in real time. The second pipe section is used only for liquid flow. Three pneumatic switching valves are installed on the second pipe section, namely the first pneumatic switching valve, the second pneumatic switching valve and the third pneumatic switching valve. The three pneumatic switching valves divide the flow path of the second pipe section into a first flow path, a second flow path and a third flow path. A first electromagnetic flow meter, a second electromagnetic flow meter and a third electromagnetic flow meter are respectively installed on the first flow path, the second flow path and the third flow path. The first flow path is a high flow rate regulating path, and the second flow path and the third flow path are low flow rate regulating paths. The diameter of the first flow path is larger than that of the second flow path or the third flow path. The manifold section has a first inlet, a second inlet, and an outlet, with the first inlet and the second inlet respectively in fluid communication with the output ends of the first section and the second section; A variable diameter pipe section, which is suitable for installing a Doppler flow meter to be traced, and is in fluid communication with the outlet of the manifold section; An observation window, comprising a first transparent window located upstream of the variable diameter pipe section and a second transparent window located downstream of the variable diameter pipe section, wherein the first transparent window is adapted to observe the fluid flow state before entering the variable diameter pipe section, and the second transparent window is adapted to observe the fluid flow state out of the variable diameter pipe section. Its features are: It also includes a control system adapted to regulate the pressure in the first pipe section and the second pipe section to keep them consistent, and adapted to control the fluid flow rate into the manifold section from the first pipe section and the second pipe section respectively. After the fluid flow into the variable diameter pipe section after being merged by the manifold section reaches a stable state, the flow rate readings in the first pipe section and the second pipe section are compared with the flow rate reading of the Doppler flow meter to achieve traceability of the Doppler flow meter.

2. The Doppler flowmeter traceability device based on gas-liquid two-phase flow according to claim 1, characterized in that: The control system uses a pressure tracking algorithm to collect the pressure signal of the first pipe section and uses a frequency converter to adjust the working pressure of the second pipe section so that the pressure in the first pipe section and the second pipe section remains consistent. A second pressure transmitter is installed on the second pipe section, which is suitable for real-time monitoring of the pressure and temperature signals of the second pipe section.

3. The Doppler flowmeter traceability device based on gas-liquid two-phase flow according to claim 2, characterized in that: An air compressor, a gas pressure stabilizing tank, a pressure reducing valve, and a filter are sequentially connected upstream of the first pipe section. A first manual regulating valve and a first electric regulating valve are sequentially connected downstream of the first pipe section. The first electric regulating valve is suitable for coarse flow adjustment, and the first manual regulating valve is suitable for fine flow adjustment. It also includes a one-way valve installed between the first manual regulating valve and the first electric regulating valve, the one-way valve being adapted to prevent backflow caused by pressure imbalance between the first pipe section and the second pipe section.

4. The Doppler flowmeter traceability device based on gas-liquid two-phase flow according to claim 3, characterized in that: The second pipe section is connected upstream of a water pump and a liquid flow stabilizer tank, which are suitable for drawing liquid from the water tank into the pipe section, and the first flow pipe is connected downstream of a second electric regulating valve. The second flow pipeline and the third flow pipeline are respectively equipped with a second manual regulating valve and a third manual regulating valve. After the second flow pipeline and the third flow pipeline merge downstream, a third electric regulating valve is connected. The third electric regulating valve is suitable for coarse flow adjustment, and the second manual regulating valve and the third manual regulating valve are suitable for fine flow adjustment.

5. The Doppler flowmeter traceability device based on gas-liquid two-phase flow according to claim 4, characterized in that: The rotary flow meter is installed downstream of the first manual regulating valve; the first electromagnetic flow meter, the second electromagnetic flow meter, and the third electromagnetic flow meter are respectively installed downstream of the first pneumatic switch valve, the second manual regulating valve, and the third manual regulating valve. The high-flow regulating pipe has a diameter of DN25 and can control a flow rate range of 500~10000L / h; The small flow regulating pipe has a diameter of DN5 and DN2.5, and the controllable flow regulation range is 70~700L / h and 18~180L / h, respectively; The control system uses a PID control algorithm to collect the gas flow signal fed back by the rotary flow meter as a feedback value to change the valve opening of the first electric regulating valve, thereby controlling the gas flow in the first pipe section; and collects the liquid flow signal fed back by the first electromagnetic flow meter as a feedback value to change the valve opening of the second electric regulating valve, thereby controlling the liquid flow in the first flow pipeline.

6. The Doppler flowmeter traceability device based on gas-liquid two-phase flow according to claim 5, characterized in that: A three-way valve is installed downstream of the variable diameter pipe section. Adjusting the three-way valve to the upward flow direction creates back pressure within the pipe section. The three-way valve is connected to a third transparent window at the top, which is suitable for observing the vertical flow state of the fluid flowing out of the variable diameter pipe section.

7. A Doppler flowmeter traceability device based on gas-liquid two-phase flow according to claim 6, characterized in that: The manifold section is a Y-shaped transparent circular tube with an included angle of 85°.

8. A Doppler flowmeter traceability method based on gas-liquid two-phase flow, comprising a pipe section and a control system, wherein the pipe section includes: The first pipe section is used only for gas flow. A first pressure transmitter and a temperature transmitter are installed on the first pipe section. The first pressure transmitter and the temperature transmitter are respectively adapted to monitor the pressure signal and temperature signal of the first pipe section in real time. A first manual regulating valve and a first electric regulating valve are connected in sequence downstream of the first pipe section. A rotary flow meter is installed downstream of the first manual regulating valve. The second pipe section, used solely for liquid flow, is equipped with three pneumatic valves: a first pneumatic valve, a second pneumatic valve, and a third pneumatic valve. These three valves divide the flow path of the second pipe section into a first flow path, a second flow path, and a third flow path. The diameter of the first flow path is larger than that of the second or third flow path. The first flow path is a high-flow-rate regulating path, while the second and third flow paths are low-flow-rate regulating paths. A second electric regulating valve is connected downstream of the first flow pipeline. A second manual regulating valve and a third manual regulating valve are also installed in the second flow pipeline and the third flow pipeline, respectively. The second flow pipeline and the third flow pipeline are connected to a third electric regulating valve after they merge downstream. A first electromagnetic flow meter, a second electromagnetic flow meter and a third electromagnetic flow meter are installed in the first flow pipeline, the second flow pipeline and the third flow pipeline, respectively. The manifold section has a first inlet, a second inlet, and an outlet, with the first inlet and the second inlet respectively in fluid communication with the output ends of the first section and the second section; A variable diameter pipe section, adapted to install the Doppler flow meter to be traced, is in fluid communication with the outlet of the manifold section; An observation window, comprising a first transparent window located upstream of the variable diameter pipe section and a second transparent window located downstream of the variable diameter pipe section, wherein the first transparent window is adapted to observe the fluid flow state before entering the variable diameter pipe section, and the second transparent window is adapted to observe the fluid flow state out of the variable diameter pipe section. Its features are: The steps of the Doppler flowmeter tracing method based on gas-liquid two-phase flow include: S1: Set the required gas flow rate of the first pipe section and the liquid flow rate of the second pipe section on the computer respectively; S2: Supply fluid to the first pipe section and the second pipe section respectively according to preset values; S3: The control system uses a pressure tracking algorithm to ensure that the pressure in the first pipe section and the second pipe section remains consistent; S4: The control system uses a PID control algorithm to control the first electric regulating valve to regulate the flow of the first pipe section and to control the second electric regulating valve to regulate the flow of the first flow pipeline. S5: Use the manifold to combine the fluids flowing out of the first pipe section and the second pipe section, so that the gas-liquid two-phase flow merges, and observe the observation window until the fluid flow in the variable diameter pipe section is stable and there are uniform bubbles. S6: Install the Doppler flow meter to the variable diameter pipe section, apply coupling agent to the surface of the variable diameter pipe section and the signal generating device of the Doppler flow meter, and fix the generating device to the outer wall of the variable diameter pipe section; S7: Compare the displayed value of the Doppler flow meter with the sum of the fluid flow rates of the first pipe section and the second pipe section to achieve traceability of the Doppler flow meter.

9. The Doppler flowmeter traceability method based on gas-liquid two-phase flow according to claim 8, characterized in that: The pressure tracking algorithm in step S3 specifically includes: Real-time monitoring of the pressure and temperature signals fed back by the first pressure transmitter and the temperature transmitter in the first pipe section; The pressure signal is converted into a corresponding control signal for the frequency converter; the computer adjusts the working pressure in the second pipe section through the frequency converter. Feedback is provided through the second pressure transmitter and the temperature transmitter in the second pipe section to maintain equal pressure in the first pipe section and the second pipe section, so as to prevent uneven pressure when the first pipe section and the second pipe section merge through the manifold section; The PID control algorithm in step S4 specifically includes: The gas flow signal fed back by the rotary flow meter is collected as a feedback value to change the valve opening of the first electric regulating valve, thereby controlling the gas flow in the first pipe section. The liquid flow signal fed back from the first electromagnetic flowmeter is collected as a feedback value to change the valve opening of the second electric regulating valve, thereby controlling the liquid flow in the second pipe section.

10. The Doppler flowmeter traceability method based on gas-liquid two-phase flow according to claim 9, characterized in that: Before step S5, the following is also included: The flow rate of the second pipeline is coarsely adjusted using the third electric regulating valve. The low-flow regulating pipeline is precisely adjusted manually using the second and third manual regulating valves: After the second pneumatic switch valve is opened, the flow rate of the second flow pipeline is controlled by the second manual regulating valve, and the flow rate is indicated by the second electromagnetic flow meter; after the third pneumatic switch valve is opened, the flow rate of the third flow pipeline is controlled by the third manual regulating valve, and the flow rate is indicated by the third electromagnetic flow meter. The flow rate of the first pipeline is coarsely adjusted using the first manual regulating valve. After the gas-liquid two-phase flow enters the manifold section and merges, the flow state in the first transparent window is used to monitor in real time whether there are bubbles in the medium that can be used for traceability and the flow stability during the traceability process. A three-way valve is installed downstream of the variable diameter pipe section. Adjusting the three-way valve to the upward flow direction creates back pressure in the pipe section, preventing the liquid phase from filling the pipe when the liquid flow rate is relatively small. The gas-liquid two-phase flow state after the variable diameter pipe section can be observed through the second transparent window. The three-way valve is connected to a third transparent window at the top, through which the flow state of the vertically flowing fluid exiting the variable diameter pipe section can be observed to see if it is stable. Change the diameter of the variable diameter pipe section, and install the Doppler flowmeter to be traced on the variable diameter pipe section to perform multiple traceability measurements.

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