Study On Gas Velocity Of Gas Liquid Two-phase Flow Measurement Technique

Gas liquid tow-phases flow widely exists in industrial production and people’s daily life. For economic, efficient and security, the flow parameters measurement of industrial production process is very important. At the same time, it is helpful to the theory of gas liquid two-phase study. But the flow of gas liquid two-phase process is quite complicated and the dispersed phase movement is three-dimensional, so the flow parameters measurement has a certain degree of difficulty. This project based on the theory of gas-liquid two phase flow detection, for the industrial filed, the froth flotation bubble rise velocity measurement is preliminary studied, designing the system of bubble rise velocity measurement.First, this paper introduce the background of gas liquid two-phase flow detection and the development of current situation in both nation and oversea briefly, and analyzes the production process of froth flotation, the examination principle of this system is also expounded, and put forward the system measurement scheme basing on the capacitance examination technologies and related flow measurement techniques. When bubbles rise in the flotation tank, it causes the random change for the equivalent dielectric constant. Meanwhile, the value of capacitance sensor also make random change. It calculates the delay time of upstream and downstream sensor random signal. So we realize the measurement of bubble rising velocity.This system uses two capacitance plates to measure the vertical velocity changes. For the capacitance examination technologies and related flow measurement techniques, this paper designs the capacitance measuring system and data processing system on PC. The section of hardware design adopts C8051F005 MCU of CYGNAL company, mainly includes the examination circuit of small capacitance, the data collecting and processing circuit, the RS-485 communication circuit. The software design of MCU is implemented under the environment of Keil, mainly implements the data collection and transmission. PC software is written in the Matlab environment, includes storage, data processing, cross-correlation calculation, results display etc. Finally, this paper get the experimental data though experiment. Analyzing and summarizing the data, it is proved that when the distance of upstream and downstream sensors is 120 mm, and it has obvious correlation, insert the sensor into 330mm,430mm,530mm of the pulp, we compared the relevant characteristics and measurement speed. The experiments show that we insert the sensor into 330mm of the pulp and measure the bubble velocity, the relevant features is obvious and speed is stable. It is proved that the method of two-phase flow detecting is a reasonable and effective way. In industrial field, it can measure the bubble velocity timely at a position depth of the pulp. To guide the optimization of production, the research results of this paper has a certain applicative value.