抄録
The Solids mixing process has been regarded as a probabilistic phenomenon which involves both convective and diffusive mixing. However, it is difficult to distinguish or separate these two mixing mechanisms —convection and diffusion— in an actual mixer.
Akao and Fan proposed a new approach called “the synthesis of a mixing system” to overcome the aforementioned difficulty. First, they separated the two mixing mechanisms as a unit operation and then constructed respective models, lastly synthesized a model mixer on the basis of these models. They reported that the approach could consistently systematize the solids mixing processes from a simple model mixer to a practical one.
The most fundamental model mixer can be realized by feeding a striated mixture, obtained from the convective mixing model, to a diffusive mixing model (probabilistic branching model). The mixing effectiveness of this mixer has been examined by increasing the number of strata in various ways. It was reported by Fan et al. that the number of strata affects the effectiveness.
However, it is recognized here that the mixing effectiveness depends not only on the number of strata but also on the pattern of the striated mixture. This paper presents the pattern that can most rapidly attain a completely mixed state. It can be concluded that an optimal feeding is the particular striated one obtained from the convective mixing model by folding operations. The optimal feeding is characterized by the repetition of the unit pattern, such as black, white, white and black. It is shown that optimal feeding requires only a few transitions to attain the completely mixed state although the others require much more. This result is of practical significance in designing a mixer.
