# Settling Slurry Pressure Loss Calculations

FluidFlow provides the user with the option of selecting one of five possible calculation methods for determining pressure loss for the flow of settling slurries through a piping system. For settling slurries, i.e., a "carrier fluid" conveying solid particles, the calculation is considerably more complicated than a liquid calculation, due to the wide range of variables involved, viz particle size and size distribution, solids density and shape, percent solids, mixture velocity, etc. The accepted approach is to determine the 'solids effect', the extra friction loss caused by the solids content over that for an equivalent flow of the carrier fluid alone. The carrier fluid may be clean water if the solids are relatively coarse with no fraction below about 0.4mm but solids smaller than 0.4mm can be held in suspension and create a 'homogeneous' carrier fluid, the friction characteristics of which needs to be determined. A number of interrelated factors influence the excess pressure drop in a pipeline over the pressure loss for water alone (or the carrier fluid if a fine particle fraction exists). The two main factors are the solids characteristics and the velocity of flow of the mixture but pipe inclination is also important. The design method is highly empirical. "Slurry Transport Using Centrifugal Pumps", by KC Wilson, GR Addie, A Sellgren and R Clift provides the best reference with a synthesis of the authors' many papers together with "Introduction to Practical Fluid Flow" by R.P. King provides some useful additions. These two references, and a considerable amount of literature research, provided the basis for the development of the FluidFlow Slurry simulator. FluidFlow simulates heterogeneous settling slurries according to five correlations: ▪Durand-Condolios-Worster ▪Wilson-Addie-Sellgren-Clift ▪WASP ▪Sellgren, Wilson Four-Component Model ▪Liu Dezhong