Self-heat recuperative fluidized bed drying of brown coal

Abstract

Brown coal drying based on self-heat recuperation (SHR) technology which recovers effectively both latent and sensible heat was developed to reduce energy consumption which is required during drying. A fluidized bed dryer (SHR–FBD) with heat exchanger immersed inside the bed was adopted as the evaporator. To evaluate the energy efficiency of the proposed SHR–FBD system, a comparison to the available mechanical vapor recompression (MVR) based drying system concerning the effect of the fluidization velocity and bed aspect ratio to the required energy input for brown coal drying was conducted. From the results, the proposed SHR–FBD system was found to be able to drastically reduce the drying energy consumption at all evaluated fluidization velocities and bed aspect ratios. Numerically, the proposed system reduced the energy consumption to about 15% and 75% of that required in hot air and MVR drying systems.