Research And Design Of Discrete Phase Concentration And Velocity Measurement In Gas/Solid Two-phase Flow

The two-phase flow phenomenon is widely exist in nature and modern industrialprocesses which is closely related to human life and production. Currently，in the chemicalindustry, energy, metallurgy, petroleum,light manufacturing, and many production facilitiesare involved in two-phase. As the two-phase flow is extremely complex, two-phase fluid iscalled unpredictable fluid. It has become a hot topic that domestic and foreign scientists andexperts eager to explore. Two-phase flow measurement parameters include the discretephase concentration, the fluid velocity, mass flow and flow patterns and so on. Real-timemeasurement of these parameters is of great significance to improve the productionefficiency.This paper designed a non-contact measurement scheme to measure the gas/solidtwo-phase flow discrete phase concentration and velocity based on capacitance sensor. Theprogram takes the Altera company’s Cyclone series FPGA chip EP2C5Q208C8as the maincontrol chip. As the FPGA with a computing speed, real-time and high reliability, which canbe used to perform on-line real-time measurement of flow rate and concentration.This paper firstly introduces the cross-correlation velocity measurement principle anddiscretes phase concentration measurement principle based on capacitive method, anddesigned a circular capacitive sensor. In order to get the capacitance signal acquisition ofsmall capacitance changes caused by the amount of solid particle concentration in gas/solid two-phase flow. Basing on integrated capacitive read tiny chip MS3110, it is designeda resolution of0.02pF, measuring range0~10pf capacitance measurement circuit. Thecircuit can take the micro capacitance values into a0~5V DC voltage signal. And wedemarcate measurement results by using precision digital bridge. Build a virtual instrumentmeasurement system, and conduct experiments offline. Then, design a correlator based onNios Ⅱsoft-core processor. Development of A/D controller and t upstream and downstreamflow noise signal data storage controller, LCD1602display controller, communication interface controller and other modules by FPGA hardware programming language. In theNios Ⅱ IDE software, use fast FFT cross-correlation function to calculate downstreamsampling data by C language, and search for the peak for the measurement of velocity.Finally, build a gas/solid two experimental platform, realize the off-line parametermeasurement by Labview. There are many factors to influence experiment results, like twosensor’s distance, sample frequency, sample points and so on. It is laid the foundation forfurther research.