Research Of Dense Phase Gas-Solid Two-phase Flow Parameters Measurement In The Horizontal Pipe

Realization of flow parameters accurate measurement for dense phase pneumatic conveying is of great significance for the metallurgy, electric power and other industries to reduce energy consumption and minimize emission. The characteristics of dense phase pneumatic conveying include complex flow pattern and parameters distribution, and typical slug flow is the typical pattern in the horizontal pipeline.In this dissertation a novel capacitance sensor array with one ring detection electrode was proposed in the terms of the quasi-periodic and pulsation characteristics of slug flow in the horizontal pipeline of dense phase pneumatic conveying, which can identify the flow pattern and the distribution of solid phase at the same time. On the basis of the optimized segmented capacitance sensor and signal detection circuit, the experimental system was build to study the measurement of gas-solid two-phase flow parameters including mass flow, concentration and speed. The main research works are as follows:(1) Studying the characteristics of dense phase pneumatic conveying in the horizontal pipeline and parameters measuring method are studied. A gas-solid two-phase flow parameters detection system was designed based on the analysis of the functional requirements, the main qualification of the system and the design goal of the system.(2) Studying the output characteristics of proposed capacitance sensor, design and produce capacitance sensor array with one ring detection electrode and speed sensor.(3) Studying the C/V conversion circuit, phase-sensitive demodulation circuit, analog switch, data selection and so on, making and debugging circuit boards based on the output characteristics of the capacitance sensor.(4) The models of slug pattern identification and slug length calculation were built with Fourier transform time-frequency transformation according to the slug flow characteristics; the solid-phase mass flow rate model was established combining the flow parameters of velocity, solid phase concentration, flow pattern and other information.(5) The PC software platform was completed in the LabVIEW development environment, which includes data acquisition, cross-correlation velocity, concentration detection, data storage and other procedures.(6) Flow parameters detection system was developed for dense phase gas-solid two-phase flow in the horizontal pipeline, In the laboratory environment, mass flow rate of dense pneumatic was measured; the system can accurately identify the flow pattern, the gas-solid flow velocity measurements relative error was less than 5% and mass flow measurement relative error was less than 10%.