Thermal breakthrough analysis for determination of energy equilibrium data in a fluidized bed

Abstract

The aim of this work was to predict energy equilibrium values in a bench-scale fluidized bed (FB: 105 × 200 mm), using a thermal breakthrough analysis (TBA). For this purpose, a simple “unsteady state” energy balance was proposed by harnessing dynamic model approach on the basis of heat exchange between the bed and the gas. To investigate thermal behavior of the bed, low temperature runs at different flow rates (5.2 ≤ Q 0, m 3 h − 1 ≤ 7.4) and heating rates (97 ≤ q, kJ h − 1 ≤ 765) were carried out. FB was heated by means of an electrical heater (10 × 50 mm) horizontally immersed into the bed particles for heating period and then the power input was terminated for cooling period. The bed temperatures ( T B) were continuously measured for obtaining thermal breakthrough curves for all periods. Temperature–time data were used for extracting bed-to-gas heat transfer film coefficients ( h BG) from linear forms of proposed model. The model was also employed for calculating amounts of shared energies by fluidized bed phases ( q y − q x ). A good agreement between experimental values and model values of T B was found. The results were thus confirmed by proposed model. The latter may be successfully used to predict energy equilibrium data for e.g. drying or combustion.