Development of a simulation model for the expansion of perlite

Abstract

New applications of expanded perlite in the building industry lead to a growing demand for process optimization for the expansion of periite. Periite expanders aim to adapt their furnaces and/or furnace operation conditions in order to attain more flexibility to produce different expanded periite qualities. A way to examine the possibilities of an existing installation is the numerical simulation of the periite expansion process in that installation. 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 the expansion of periite. This model is based on the results of fundamental studies concerning the expansion phenomenon. It relies on the calculation of particle temperature and viscosity and thus takes into account the most influential parameters for perlite expansion. It allows the calculation of the perlite particle size as a funedon of time or of the particle's trajectory inside a furnace. Particle size statistics of the expanded product can be determined in that way. The model has been validated by comparison with experimental results from laboratory and industrial measurements.