Numerical analysis of the Gas − Solid heat transfer characteristics of a lightly calcined MgO Fluidized-bed roaster

Abstract

The fluidized bed roaster is a novel energy-efficient calcination device for lightly calcined magnesia production. However, the gas − solid heat transfer process in the roaster, the key which can significantly impact energy consumption and product quality, has not an in-depth study yet. In the present work, for the determination of the optimal operating parameters of the roaster, the Euler-Lagrange model of ANSYS Fluent software was employed to simulate the influence of inlet temperature and flow rate of flue gas and feed amount of magnesite on the temperature distribution, production capacity and decomposition rate. The results show that the specific energy consumption is reduced by approximately 6.45 % under the optimal operating conditions with production capacity of 5 × 104 t/a. Furthermore, the maximum production capacity reaches 5.5 × 104 t/a with 9.2 % reduction of specific energy consumption when the feed amount, flue gas flow rate and flue gas temperature are optimized as 14.5 t/h, 21,000 Nm3/h and 1660 K, respectively.