Study of multi-acoustic channel supersonic Doppler flowmeter for measuring coal slurry-coal log pipeline

Abstract

Coal slurry-coal log pipeline is a new technology for long distance transportation of coal logs (cylindrical coal briquettes) by using coal slurry as carrier and pump as power set. Because of the difficulty of measuring flow rate of coal slurry-coal log pipeline, the study of measuring technology and the development of flowmeter are necessary. In consideration of the characteristics of transportation of coal logs in coal slurry pipeline, a non-contacting measuring method and the supersonic Doppler effect are selected and used. By detecting frequency drifts produced by reflecting supersonic wave from moving coal particles and coal logs in pipeline the flow rate of coal slurry-coal log pipeline (the total quantity of coal transported by the pipeline) can be measured. Based on the concept of liner concentration of coal logs in pipeline and characteristics of Doppler frequency drifts of coal particles and coal logs moved in pipeline, the measuring method of supersonic wave and the transportation principle of coal slurry-coal log pipeline are discussed and a multi-acoustic channel supersonic Doppler flowmeter is designed for measuring the total quantity of coal transported by pipeline. The flowmeter is composed of supersonic transducer, electron circuit, flow rate indication and integral calculation system. The multi-acoustic channel technique and a suitable acoustic wedge with a certain shape and special solid material are selected and used for increasing the measuring precision. In this paper the Doppler signal is measured and analyzed by using mixing-frequency technique and FPT (rapid Fourier transformation), and some designed circuits and signal measurement process are also offered.