Zoltan Turzo & Gabor Takacs PhD., University of Miskolc & Janos Zsuga, MOL Pltd.
The variation of centrifugal pump performance curves with liquid viscosity is a well-known fact and is usually properly accounted for when selecting such pumps for oilfield service like artificial lifting by ESP units, pipeline transport, etc. Thus, several theoretical and empirical methods are available for correcting performance curves (conventionally measured with water) to other liquids. Most of them utilize specially developed charts and tedious hand calculations and are viable for simple design calculations but find very limited use when a great number of cases is present or when computerized calculations are desired. The aim of the present paper is the development of specific formulas instead of charts to be used for correcting the performance curves of centrifugal pumps for higher viscosities. The formulas are based on the widely used and generally accepted procedure of the Hydraulic Institute whose previously published charts, after digitalization, were fitted with analytical functions of the relevant parameters. The model introduced in the paper easily lends itself to computer applications and may be used as a subroutine in many kinds of program packages that involve selection or evaluation of centrifugal pumps. The use of the model is illustrated by a detailed example problem. At the end of the paper, two additional examples are shown to prove the accuracy of the proposed model. Here, calculated performance curves are compared to actually measured ones for two pumps in pipeline service. The two examples prove that the proposed analytical model gives very good accuracies.