About residence time distribution of dissoluble solid particles in the
cascade of apparatus with mixing devices.
Fedorov S.P., Lunev V.D.
The transfer of matter from a solid phase in solution is relevant constituent of acceleration
of processes of chemical interaction reacting components. At equipment design of continuous processes, in which one
limiting stage is the dissolution of initial raw material, the information on cumulative distribution functions of
solid particles on a residence time in the cascade of reactors, permitting to calculate an optimum volume of the
cascade and technological process conditions, is indispensable.
If the particles have the insoluble substrate (processes of leaching etc.), the cumulative
distribution function for particles does not differ from those for a suspension as a whole, or liquid phase. In that
case, when the particles can completely be diluted during process, the probability of their appearance on exit of
the cascade will be peer to null since some definite for each given particle instant, dependent on its initial size
and speed of dissolution. Therefore more small-sized particle with the greater probability can completely be dissolved
in the cascade before its appearance on an exit, than larger. Thus, dispersed structure of an initial solid component
and speeds of particles dissolution renders essential effect on their cumulative distribution functions of
probabilities of a residence time in the cascade of reactors. According to said above, the mean time of stay of
dissoluble particles in the cascade, adopted for environment as a whole, appears considerably overstated.
In the given advertisement on the basis of the solution of a kinetic equations system for a frequency function of
distribution of inclusions on the sizes, circumscribing processes of dissolution of polydispersed systems in the
cascade of reactors, the expressions for the probabilistic characteristics of a residence time of dissoluble solid
particles in the cascade for a case of identical motive power of process in all its stages are obtained.
The effect of a dispersed structure of initial raw material and speeds of dissolution of
particles on a cumulative distribution function of a residence time probabilities of these particles in the
cascade of stirred vessels is reflected. Theoretically and direct calculations is significant, that the mean times of
stay of dissoluble solid inclusions and suspensions in the cascade of reactors differ among themselves, their
comparison for different values of a degree of dissolution of raw material and different number of stages in the
cascade is adduced.
The full text is published in \\ Журн. прикл. химии (Journal of applied chemistry of the
USSR), 1988, V. 61, № 8, P. 1816-1820.
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