Sustainable biomass processing: Optimizing energy efficiency through ash waste heat recovery for fuels dewatering

Biomass power generation technologies face challenges in cost competitiveness due to high energy consumption during dewatering. Utilizing waste heat for fuel dewatering is a viable solution to reduce energy consumption and improve efficiency. Herein, spherical heat carrier (SHC) was prepared by encapsulating sand using metal spherical shell, providing a low cost and efficient means for transferring ash heat to dewater biomass. The effects of temperature of heat source (ash or SHC), mixing mass ratio, loading of sand and moisture content of biomass on the recovery and utilization of ash waste heat, and dewatering effect of biomass were optimized by using response surface method. As results, ash temperature and mass ratio were the main factors affecting heat recovery rate and the effective heat transfer coefficient in the heat exchange between SHCs and ash, while SHC temperature and moisture content were the main factors of dehydration rate and the effective heat transfer coefficient in the peanut shells dewatering. The optimal overall thermal efficiency of the continuous process was 36% and the specific energy consumption was 2.13 kWh·kg_water^-1. This work provided a technically feasible and efficient way for biomass ash waste heat utilization and biomass fuel dewatering.