Design And Implementation Of Gas-liquid Two-phase Flow Monitoring System Based On Wire Mesh Sensor

The monitoring needs of gas-liquid two-phase flow are widely found in many occasions such as nuclear reaction,petroleum smelting,biochemical reaction and so on.The realization of a wide range of gas-liquid two-phase fluid measurement and image reconstruction has great benefits for the study of related reaction mechanisms,as well as the realization of accurate material control and production safety.The use of high-speed cameras can achieve non-contact gas-liquid two-phase flow monitoring,but it has the disadvantages of high cost and limited use occasions;electrical tomography has the advantages of fast response speed,but also has the problems of low measurement accuracy and poor imaging effects;it has become an important gas-liquid two-phase flow monitoring method to use the wire mesh sensor to monitor in the pipeline,which has the advantages of response speed,imaging effect and economy.However,the domestic research on the use of wire mesh sensor for gas-liquid two-phase flow monitoring started late.Most of the existing research results have been completed through cooperation with foreign countries,and the core part is still controlled by foreign countries.Based on the above background,the thesis designed a visual monitoring system for gas-liquid twophase flow with wide measurement range and low cost.The paper proposes a pulse-stimulated line-scanning screen monitoring scheme,studies the image reconstruction algorithm,and integrates the embedded development technology to complete the design and prototype production,debugging and testing of the gas-liquid two-phase flow monitoring system based on wire mesh sensor.The work realized the real-time visual monitoring of the phase information of the pipeline section.The main work of system hardware design includes: designing the main control module to coordinate and control the stable and orderly operation of each module;designing the excitation module to realize the sequential control of multi-channel stable amplitude bipolar voltage excitation signals;designing the receiving module to complete the multi-channel weak current response The signal undergoes I/U conversion and the quantitative collection of the amplified voltage signal;the communication module is designed to realize the communication function between the computer side and the embedded side.The main tasks of the system software design are: the completion of the saving and adjustment of the gain parameters of the program-controlled amplifier circuit,the effective control of the op amp gain;the excitation scanning,signal acquisition and processing and network communication are completed to achieve accurate acquisition and fast upload of phase state information of pipeline section;designed the communication protocol at both ends;completed the software design at the computer end,which provided convenience for system function debugging and reconstructed image display.The main contributions of the paper include:(1)For the measurement signal is weak and vulnerable to interference,I/U conversion,amplification,filtering and other processing methods are used to effectively improve the accuracy of the measurement data.(2)For the problem of poor direct imaging effect of measurement data,the cubic spline interpolation algorithm and median filter algorithm are used to process the measurement data to achieve a more realistic restoration of gas-liquid two-phase flow imaging images.(3)Aiming at the problem that single liquid and gas two-phase flow monitoring system is difficult to meet the application demand,the two-stage amplifying circuit design scheme is adopted and the gain size is adjusted by digital potentiometer to improve the adaptability of the system to a variety of gas-liquid two-phase flow monitoring environments.After testing,the gas-liquid two-phase flow monitoring system designed in this paper fulfills all the functional requirements.The system is simple in operation and stable in operation.All performance indicators have reached the expected target and have certain practical value.