Pipeline design procedures for cattle and pig slurries using a large-scale pipeline apparatus.

摘要

A large-scale pipeline apparatus was built to investigate the turbulent flow properties of farm livestock slurries and to enable the development of a pipeline design procedure. The apparatus was designed to measure pressure gradients of liquid flows from 120 to 700 l/min in pipes of different internal diameters (38.1, 50.8, 76.2 and 102 mm). Results were obtained using water, pig slurries containing total solids concentrations Ts up to 4.4% and dairy cattle slurries with Ts values up to 5.5%. Measurements of pressure gradient and flow rate were converted into values of wall shear stress and nominal shear rate to produce characteristic relationships for each liquid in each pipe. Hence, it was shown that a three-parameter pipeline design procedure could provide a suitable basis for predicting pressure losses in pipes of other diameters, including surface roughness effects. Experimental assessment of the design procedure revealed an intrinsic risk of systematic correlation between two of the three parameters. Hence, an approach was devised to alleviate this problem by reducing the number of parameters to two. It was found that the resulting two parameters could each be represented by a linear function of Ts, enabling convenient prediction of pressure losses for other slurries.