1070-4272/05/7808-1294 + 2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 8, 2005, pp. 1294!1300. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 8, 2005,
Original Russian Text Copyright C 2005 by Yablonskii.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Effect of Rheological Properties of the Dispersion Medium
on Separation of Suspensions in Hydrocyclones
with Various Working Space Configurations
V. O. Yablonskii
Volgograd State Technical University, Volgograd, Russia
Received March 16, 2005
Abstract-The model of separation of suspensions with a non-Newtonian dispersion medium in a cylindro-
conical hydrocyclone, which takes into account the effect of the Coriolis force on solid particles, was
constructed and applied to analysis of the rheological properties of the dispersion medium on separation of
suspensions in hydrocyclones with various working space configurations.
Hydrocyclones are one of multi-purpose types of
apparatus for separation of heterogeneous systems in
chemical, microbiological, food, and other industries.
Use of hydrocyclones yields a pronounced economic
effect through intensification of technological proc-
esses. The economic feasibility and efficiency of sep-
aration processes are determined by the degree of
thickening of the dispersed phase and by its loss. In
this context, optimizing the design parameters of
hydrocyclones and determining the optimal modes of
their operation are important problems, which can
lead, when solved, to intensification and accelerated
development of numerous branches of industry.
Until now, there has been no rigorous theory of
motion of two-phase systems in a swirling vortex
flow. The overwhelming majority of modern studies
 are based on the equation of a unidimensional
motion of a small spherical particle suspended in
a viscous incompressible turbulent flow.
In , methods for calculation of predictable sep-
aration parameters and other important performance
characteristics of cylindroconical hydrocyclones were
developed in the framework of a unified stochastic
approach. As noted by the authors, an exact analytical
description of particle motion in a centrifugal field,
based on Navier3Stokes and flow continuity equa-
tions, requires that a number of not quite correct as-
sumptions should be made, because of the complexity
of the hydrodynamic situation in hydrocyclones,
which impairs the adequacy of the suggested analyt-
ical descriptions of the real hydrodynamic pattern.
In [2, 3], fundamental aspects of a calculation of
turbulent particle transport in a hydrocyclone, based
on the continuity equation for the solid phase flow,
were considered. Such an approach makes it possible
to calculate both the amount of the solid phase re-
covered in a hydrocyclone and its parameters (concen-
tration, granulometric composition) at any point of
the apparatus. In , a numerical study of the flow
structure and separation processes in a hydrocyclone
was carried out using the Navier3Stokes equations.
The momentum transfer by the dispersed phase was
described in terms of the theory of multispeed con-
tinuum. By now, the equation of radial motion of
particles in hydrocyclones of various designs has been
solved with account of the action of inertia and Co-
riolis forces on a particle . This made it possi-
ble to calculate the size distribution of particles of
the dispersed phase and to determine their content in
target separation products.
The difficulty encountered in solving equations that
characterize sedimentation of solid particles in a hy-
drocyclone consists in that, in order to satisfy the re-
quirement that the system of equations should be
closed, it is necessary to use those solutions to equa-
tions of hydrocyclone hydrodynamics, which rigor-
ously relate the circumferential, radial, and axial com-
ponents of the fluid velocity over the entire working
space of the apparatus. In addition, suspensions sep-
arated in chemical industry are, in most cases, non-
Newtonian media whose effective viscosity decreases
as the intensity of deformation rates becomes higher,
which affects the hydrodynamics of apparatus.