Flow measurement in pneumatic transport of pulverized coal

Abstract

The paper also deals with the measurement of particle velocity. Particle velocity is the most fundamental parameter in the study of solids' movement by gases. However, its experimental determination is difficult. In most of the investigations of pneumatic transport of solids, the particle velocity either was measured indirectly or was inferred from theory. More recently, various techniques, such as the LDV (Laser Doppler Velocimetry), the tagging technique, or the double-solenoid technique, were advanced to measure the particle velocity directly. However, the usefulness of these techniques was limited, e.g. the LVD method could be used only in the dilute phase, and the tagging method needed a clean and transparent pipe. Recently, Mathur and Klinzing have used a cross-correlation technique for the measurement of the particle velocity in a coal/gas system using signals from two Auburn Monitors. These devices were expensive, and a more economical solution of the problem was sought. The possibility of using an Auburn triboelectric instrument that is based on the static charge transfer technique, was explored. The device in its original form was capable of indicating a flow or no-flow condition of solids in the pipe. The triboelectric devices were modified for our application so as to provide two matching signals, which could then be cross-correlated to yield particle velocity. Preliminary results using triboelectric devices are quite encouraging.