Conditioning the fluidization behaviour of a Geldart's B solid at varying temperature by addition of A particles

The addition of a limited amount of fines to a fluidized bed of high-density, free-flowing particles has been tested over a wide field of temperatures (from room level to 600 °C) as a method to improve the aeratability of the bulk and to achieve smooth fluidization. The bi-modal nature of the particle size distribution lends to the bed properties which are typical of solids of Geldart's group A: interparticle forces thus introduced into the bed cause the tensile strength and the Carr index of the system to assume values close to those of the fine particles, in spite of their smaller presence. As typical of A solids, the amplitude of the fluidization velocity interval of the bed after fine addition increases with process temperature, an effect that provides further confirmation of the prevailing role of the fines added on the characteristics of the fluidization regime.