Influence of crosswise non-homogeneity of particulate flow on residence time distribution in a continuous mixer

The objective of the study is to develop a mathematical model of continuous mixing of granular materials, which takes into account the crosswise non-homogeneity of particulate flow inside a mixer. The target function of modeling is the residence time distribution of a tracer injected into the inflow. The model is built on the basis of the theory of Markov chains. The working space of a mixer is presented as a 2D array of perfectly mixed cells, through which the tracer travels according to the matrix of transition probabilities. The model covers the tendency of the tracer to upward/downward segregation. Finally, for a given flow pattern, the model allows calculating the RTD curves for various throughputs and for various properties of an imperfect tracer.

A 2D cell model based on the theory of Markov chains is proposed. It takes into account crosswise non-homogeneity of particulate flow, which can be restored from the hold-up–throughput correlation. This non-homogeneity depending on its form leads to deformation of the residence time distribution curve, which can be predicted with the model. Experimental validation of the model is done.Figure optionsDownload as PowerPoint slide