Drying Energy Saving by Applying Self-Heat Recuperation Technology to Biomass Drying System

An advanced energy saving system with air as the drying medium was proposed based on self-heat recuperation technology for the biomass drying in this work. Compared to the previously developed design, the advanced process consumes less energy by considering heat pairing which means the sensible heat is paired with sensible heat and latent heat is paired with the evaporation heat, and then reduces temperature difference between the hot and cold streams in the heat exchanger. The innovitive drying concept was applied to both the co-current dryer (the fluidizied bed dryer) and the counter-current dryer. For the fluidized bed drying system, we introduced a multistage fluidized bed as the evaporator for more energy saving to reduce exergy loss during the drying process. Over 30 % of energy could be reduced compaired to the single-stage fluidized bed dryer. The advanced drying concept was also applied to the counter-currrent heat exchange drying systems which were rotary and screw conveyor dryers in this study. Energy consumption in these new developed drying system is qulifed and compaired through the process simulator. Results shows that energy consumption could be reduced to 1/4-1/6 of a conventional heat-recovery dryer based on our simulation results.