Developing Model for Pressure Drop for Dense-Phase Pneumatic Conveying of Fly Ash

Abstract

Dense-phase pneumatic conveying of powders is becoming increasingly popular in various industries such as power, pharmaceutical, cement, alumina, chemical, limestone, refinery, and so on. Some of the reasons include: minimum gas flows and power consumption; improved product quality; increased workplace safety. Various popular/existing models (and model formats) for solids friction (for straight horizontal pipes) have been evaluated for scale-up accuracy and stability. It has been found that the models (and their use of parameter groupings) are generally not capable of accurately predicting pressure drop under scale-up conditions of pipeline diameter and/or length. The PCC plotted from the data obtained from the modified Stegmaier (1978) model for four layer modelling approach for fly ash was too over predicted, the reason for that was the Stegmaier model worked which with ESP dust quite effectively rather than fly ash. For this reason the Weber (1981) model was taken and modified for predicting the pressure drop for dense phase region and plotted the PCC with the experimental data. The modified Weber (1981) model results in over prediction for diameter and length scaled-up conditions for fly ash, however these over prediction generally occurred due to diameter and length scale-up. There seems to be a substantial relative improvement in the accuracy of pressure drop predictions.