(114a) The Importance of the Residence Time Distribution for Designing Solids Handling Process Plants

Most of the intermediate and final products in the chemical or polymer industry are handled as bulk solids. Unit operations for these materials need be designed based on their material properties. A typical example is the use of the flow properties such as the internal friction and wall friction of bulk solids for mass flow of silos.

Continuous production processes become more and more important and call for the accurate performance. Key information for designing and dimensioning of the continuous process in industrial sized plants is the residence time distribution of certain vessel and apparatus but also of the interaction of the entire system. For bulks solids, the residence time distribution of such an apparatus is strongly influenced by the product itself.

Therefore a model has been applied to predict or define the residence time distribution of process silos (drying, degassing, blending) taking into account the measured product properties. Based on the results of the single equipment the effect of combining subsequent apparatus can be simulated by using the convolution integral method.

The model and also the results will be presented for the downstream pellet degassing or drying process in polymer production plants where continuous operation can be efficiently applied. The results have been used for an improved selection of equipment type, size and number.