Assessment of the derating methods for centrifugal pump performance handling non-Newtonian fluids

Oil and Gas applications commonly require the displacement of a huge amount of processing fluids. In most cases, these fluids consist of solid rock particles transported by water, e.g. kaolin or bentonite powder, which show non-Newtonian behavior. For this kind of fluid positive displacement pumps are usually recommended, but where high flow rates have to be guaranteed, centrifugal pumps are installed. Since most of the manufacturers provided the performance curves only with water, choosing the appropriate centrifugal pump to handle mineral slurries may be very challenging. Since the viscosity of this kind of fluids varies with the imposed stress and rheology, pumping this type of fluids can lead to a considerable variation in the pump head, and thus, overall efficiency is difficult to-be-predicted. Several reliable methods to predict the centrifugal pump performance in handling high-viscous Newtonian fluids can be found in literature, e.g. the well-known Hydraulic Institute method. Nevertheless, no general practical correlations are provided for non-Newtonian fluids. Previous experimental investigations on centrifugal pumps reported high-performance instabilities at low flow rates when non-Newtonian fluids are considered. Further investigations are needed to define which parameters in the pump fluid interaction have to be considered in the derating process. In this work, an assessment of the prediction quality of the existing derating methods from the literature is carried out. For this purpose, the data obtained from previous experimental investigations on a small commercial centrifugal pump handling mixtures of water and kaolin are considered.