Effect of bend model on prediction of pressure drop for pneumatic conveying systems
This paper is aimed at demonstrating the requirement of selecting a proper bend model for accurately estimating the total system pressure loss for the dilute and fluidised dense-phase pneumatic conveying of powders. Three popular/applicable bend models were used to predict the total pipeline pressure drop for pneumatically transporting power station fly ash (median particle diameter 30 mm; particle density 2300 kg/m3, loose-poured bulk density 700 kg/m3) in a test rig with 69 mm internal pipe diameter, total pipeline length of 168 m, including five 1-m radius 90 degree bends. Using appropriate particle-wall friction factor equations (based on straight pipe data) and the three bend pressure drop models, the predicted pneumatic conveying characteristics (PCC) were compared with the experimental PCC. The subsequent comparisons show that there is a significant variation between the trends of the predicted PCC (in terms of over-/under-prediction and the shape of the predicted plots with respect to theexperimental data and trends).