An Investigation Into Pressure Drop Through Bends In Pneumatic Conveying Systems

This paper results from an ongoing research into the modeling of losses due to bends in pneumatic conveying systems. An accurate estimation of pressure drop in bends is important for the reliable prediction of total pipeline pressure drop. Several existing bend pressure drop models have been discussed. Using appropriate particle-wall friction factor equation (based on straight pipe data) and the three bend pressure drop models, the predicted pneumatic conveying characteristics were compared with the experimental conveying characteristics. The comparisons show that there is a significant variation between the trends of the predicted conveying characteristics (in terms of over-/under-prediction and the "shape" of the predicted plots with respect to the experimental data). A theoretical framework for flow through the bends has been provided. Based on the conveying data of gray cement, fly ash and white cement, conveyed through 42 and 53 mm bend or pipeline diameters, radius of curvatures of 1000, 800 and 600 mm and having two different test bend locations, a new model for bend loss has been provided.