Numerical modeling of the degassing process of a gas-liquid mixture in hydrocyclone

About the authors:

Artem I. Varavva, Chief Specialist, Gazprom Neft (Tyumen); artevar@yandex.ru

Vladimir E. Vershinin, Associate Professor, Department of Physical Processes and Systems Modeling, University of Tyumen; eLibrary AuthorID, Scopus AuthorID, v.e.vershinin@utmn.ru

Dmitry V. Trapeznikov, Mathematical Modeling Engineer, Automation and Digital Modeling Department, University of Tyumen; d.v.trapeznikov@utmn.ru

Abstract:

Centrifugal separators — hydrocyclones — are widely used in many areas of the national economy to separate mixtures of substances of different densities. Hydrocyclones can be used for phase separation in oil, water and gas flow measurement units. The flow from the well is initially a three-phase mixture. The hydrocyclone separates the gas and liquid phases at the inlet of the measuring unit, which are then transferred to separate gas and liquid measurement units. Maintaining the accuracy of the phase flow measurement when using hydrocyclones in the measuring units requires high quality separation over a wide range of flow rates and phase contents. One of the directions of forecasting the characteristics of the separation process is based on the numerical solution of the equations of hydrodynamics of multiphase flows. Modern software of computational hydrodynamics allows to solve problems of such class in three-dimensional statement and thus to estimate efficiency of work of the device and its metrological characteristics.

This paper studies the processes of separation of gas-liquid mixture in hydrocyclone at different volume gas content and phase flow rates. The authors present a mathematical model with indication of the main assumptions and formulate the boundary conditions of the problem. Calculations were carried out on the open platform OpenFOAM with the use of interFoam solver. The results of numerical modeling have determined the basic structures of currents in the hydrocyclone. The influence of the initial gas content on the separation efficiency at different flow rates is investigated. The main reasons for the decrease in separation efficiency at low gas content values are revealed. In addition, the influence of the guiding elements on the separation process is considered.

References:

1. Baranov D. A., Kutepov A. M., Lagutkin M. G. 1996. “Calculation of separation processes in hydrocyclones”. TOHT, vol. 30, no 2, pp. 117-122. [In Russian]
2. Belov I. A., Isayev S. A. 2001. Modeling of Turbulent Currents. St. Petersburg; Baltic State Technical University. [In Russian]
3. Ievlev V. M. 1990. Numerical Modeling of Turbulent Currents. Moscow: Nauka. [In Russian]
4. Kopysov S. M., Tonkov L. E., Chernova A. A. 2015. “Application of VOF and SPH methods for solving problems with developed free surface”. Izvestiya IMI UdGU, no 2 (46), pp. 76-84. [In Russian]
5. Loitsyanskii L. G. 1978. Mechanics of Liquid and Gas. Moscow: Nauka. [In Russian]
6. Matvienko O. V., Agafontseva M. V. 2012. “Numerical research of degassing process in hydrocyclones”. Tomsk State University Journal of Mathematics and Mechanics, no 4 (20), pp. 107-118. [In Russian]
7. Nigmatulin R. I. 1987. Dynamics of Multiphase Media. Vol. 1. Moscow: Nauka.[In Russian]
8. Yun A. A. 2009. Theory and Practice of the Turbulent Currents Modeling. Moscow: URSS. [In Russian]
9. Hirt C. W., Niсhols B. D. 1981. “Volume of fluid (VOF) method for the dynamics of free boundaries”. Journal of Computational Physics, vol. 39, no 1, pp. 201-225. DOI: 10.1016/0021-9991(81)90145-5
10. Issa R. I. 1986. “Solution of the implicitly discretised fluid flow equations by operator-splitting”. Journal of Computational Physics, vol. 62, no 1, pp. 40-65. DOI: 10.1016/0021-9991(86)90099-9