An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors.

Jian Li,Shimin Wang,Ying Fan,Chuanlong Xu,Ming Kong

doi:10.3390/s151229843

Abstract

The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

Highlights

Pneumatic conveying is one of the most important ways for the transportation of pulverized fuel materials in many fields such as energy, chemical, metallurgy, pharmaceutical and foods industries
Great advances have been made in particle velocity measurement in gas-solid flow by using electrostatic sensors along with signal processing algorithms such as cross-correlation [10,11,12,13,14] and spatial filtering [15,16,17] techniques, and encouraging results have been obtained in both laboratory and field experiments
The mass flow rate of solid particles over the cross-section of a pneumatic pipe can be inferred from the particle velocity and concentration: M “ ρ Avβ where M is the mass flow rate of solid particles, ρ is particle density, A is the cross-sectional area of the conveying pipe, v is the mean particle velocity and β is the mean volume concentration

Summary

Introduction

Pneumatic conveying is one of the most important ways for the transportation of pulverized fuel materials in many fields such as energy, chemical, metallurgy, pharmaceutical and foods industries. A variety of advanced measurement techniques have been investigated and developed for the flow measurement of pneumatically conveyed solid particles based on different sensing principles [1], such as optical [2,3], digital imaging [4,5], acoustic [6,7], radiometric [8] and electric methods [9,10,11,12,13,14,15,16]. An integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensors is developed. Experimental results are presented to evaluate the performance of the developed system

Measurement Principle

Particle Velocity Measurement Based on Electrostatic Sensors

Particle Concentration Measurement with Capacitance Sensor

Experimental Results and Discussion

Calibration of the Capacitance Sensor

Measurements on a Gravity-Fed Rig