Abstract:
The interaction of fine particles with an expanding
gas flow under fluidization conditions is considered. The
objects of study are finely dispersed materials, their single
particles, gas flow in a fluidized layer. The study used the
laws of dynamics and hydrodynamics, the classical laws of
mechanics, as well as mathematical methods for the analytical solution of equations. It is emphasized that when
a particle moves upwards in a gas jet, three forces act
on it: the resistance force Fc, the gravity force P, and the
Archimedes force A. As a result, the motion of a fine particle
in an expanding gas flow is described taking into account
the law of dynamics. During the study, an analytical equation was obtained to determine the velocity of a particle
during its rise and fall in a gas jet. During the study, an
analytical equation was obtained to find the height of the
particle ascent depending on the gas flow rate for given
geometric parameters of the gas flow. The obtained formulas can be used in the process of studying the process of
convective drying of finely dispersed materials for various
design parameters of the dryer. In practice, as a rule, there
are various empirical formulas that describe such interactions of particles for specific parameters, which make
it difficult to generalize them. In this work, the correctness of the assumed conditions necessary for the analytical solution of the differential equation of particle motion
is proved. As a result, formulas were obtained that make it
possible to determine the velocity of a particle in a gas jet
and the height of its rise depending on the gas flow rate.
On the basis of these formulas, graphic dependences of
the gas velocity in the jet on the height Vg=f(Z), as well as
the dependences of the height of the particle rise hm on the
air flow rate in the jet L at different jet expansion angles
α=15°; α=20°; α=30° are plotted. It was found that with an
increase in the height Z in an expanding jet, the gas velocity in the jet Vg decreases, with an increase in the air flow
rate in the jet L, the height of the particle rise hm increases.
These formulas are the basis for further consideration of
the movement of particles in a fluidized layer in the process
of convective drying of fine materials for its intensification of the drying process
