MATHEMATICAL MODELING OF THE CHARACTERISTICS OF OIL PUMPS, TAKING INTO ACCOUNT THE VISCOSITY OF THE TRANSPORTED OIL

Abstract

For solving a range of assignments concerning design and operation of main oil pipelines it is necessary to possess appropriate mathematical models of centrifugal pump characteristics as the pumps appear to be the main equipment of pumping stations. Known analytical dependences describe only operating envelope of the pumps and thus can`t be applied for low flowrate regimes being inherent to the Ukrainian oil transmission system. In addition, these mathematical models do not take into account the effect of the viscosity of the transported oil on the pressure and energy characteristics of oil pumps. The work features the improved the method of mathematical modeling of the hydrodynamic characteristics of centrifugal pumps of main oil pipelines for the full range of working feeds, taking into account the effect of the viscosity of the pumped oil. It is also given a consideration to mathematical models of oil pumps characteristics, coefficients of which are found by the coordinates of two or three points of corresponding charts, and polynomial models, the coefficients of which are determined by the least squares method by a set of passport or experimental data. Adequate mathematical models for pressure characteristics and efficiency coefficient of oil pumps are proposed that are suitable for creation of computational algorithms for determining the throughput and energy efficiency of operation of main oil pipelines. It has been proved that for oil pumps that are operated under different combining schemes with significant reduction of theirs operation flowrate the advantage should be given to the mathematical models of the characteristics obtained by the method of least squares. In this case, polynomial models of the third degree provide the necessary accuracy of the calculations. The method of introducing a control unit for the influence of the transported oil viscosity on the characteristics of the pumps is proposed under determining the capability and energy efficiency of operation of main oil pipelines