Research On Digital Vortex Gas Flowmeter With Low Power Consumption

The vortex flowmeter has a good growth rate now. Because of its advantages of adaptive to various media, stability, low pressure loss and wide flow rate range, vortex flowmeter has been widely used in many different fields such as chemical industry, petroleum, metallurgy, light industry, food industry, etc. However, vortex flowmeter is under developing now. It still has some limits in understanding of basic theory and experience of practical application. Therefore, there are some problems, especially for its poor performance when measuring low flow rate where the signal is affected by different kinds of noise and the Signal-to-Noise ratio is very small. As a result, vortex flowmeter have unsatisfying measurable low limit value and smaller measurement range ratio of 1:10 compared to theoretical ratio 1:100. In order to solve this problem, many researchers have advised to use the method of digital signal processing. Under this background, a pulse output model digital vortex flowmeter has been developed successfully by Xingjuan and Duan Ruifeng, which has both DSP and MSP430 microcomputer, a double core structure. Based on previous efforts, a deep research on the digital vortex flowmeter was given in this thesis.The mainly works of this thesis are as following.1. The power consumption of the digital vortex flowmeter was reduced from 13 mA to 3.7 mA, and the 4~20 mA two-wire system analog output was realized.2. A low power consumption digital vortex flowmeter was successfully produced. The flowmeter was tested respectively on water flow experiment facility and critical flow nozzle gas flow standard facility at Process Detect & Control Laboratory in Tianjin University. It was shown by the data that the digital flowmeter has a better measurable low limit value than the analog one.3. The data of experiments under different pressure on the sonic nozzle facility shows that the meter factor K of vortex flowmeter is not affected by the fluid density. Therefore, vortex flowmeter is more suitable to measure gas flow than float flowmeter and differential pressure type flowmeters.Through the continuous further study on digital vortex flowmeter, a lot of problems have been gradually solved. Its measurable low limit value has been reduced effectively, and the system functions have also been developed. Certainly, in the soon future, digital vortex flowmeter is going to be used more widely in industry, for its advantages of lower measurable low limit value, high capacity of anti-interference, good real-time measurement performance, and highly practical value.