Development of a simulation model for the expansion of perlite

New applications of expanded perlite in the building industry lead to a gro wing demand For process optimization for the expansion of perlite. Perlite expanders aim to adapt their furnaces and/or furnace operation conditions i n order to attain more flexibility to produce different expanded perlite qu alities. A way to examine the possibilities of an existing installation is the numerical simulation of the perlite expansion process in that installat ion. The two-phase flow field and combustion in the furnace can be modelled by using currently available Computational Fluid Dynamics (CFD) codes. The only problem is the modelling of the expansion process. which changes the particle size and thus influences the two-phase flow calculations. In this paper the authors propose a physical model for the simulation of th e expansion of perlite. This model is based on the results of fundamental s tudies concerning the expansion phenomenon. It relies on the calculation of particle temperature and viscosity and thus takes into account the must in fluential parameters For perlite expansion. It allows the calculation of th e perlite particle size as a function of time or of the particle's trajecto ry inside a furnace. Particle size statistics of the expanded product can b e determined in that way. The model has been validated by comparison with e xperimental results from laboratory and industrial measurements.