Slurry Flow Velocity, Concentration and Particle Size Measurement Using Flow Noise and Correlation Techniques

Abstract

Three areas of slurry pipe flow measurement using flow noise and correlation techniques are described. Signals generated by the natural turbulence inherent in the flow of two-component fluids can be used to enable the total volume flow rate, concentration and particle size of the discontinuous component to be measured. Total volume flow is measured by a cross correlation method which involves obtaining the time of flight of a tagging signal due to the turbulence between two transducers spaced axially along the direction of flow. Both ultrasonic and conductivity transducers are used to detect the flow turbulence. Results show that a measurement accuracy within ±2% can be achieved in all systems tested. The intensity of the flow noise detected by a simple transducer is related to the quantity of the discontinuous component present in the flow. This flow noise is measured by an AC method and gives direct indication of the concentration of the discontinuous component. Turbulent flow consists of eddies which have characteristic size ranges. The motion of particles in a turbulent flow field is a function of the particle size and shape, and the density of the particles and of the fluid. A measure of the eddy size based on the spectral analysis of the flow noise can be used to give an indication of the mean particle size.