Process modeling and energy consumption of fry-drying and torrefaction of organic solid waste

A commercial fry-drying and torrefaction (FDT) plant for producing bio-solid fuel from 45 ton/d organic sludge with 80% water was proposed. The FDT plant was modeled by a process simulator with the aid of plant data. Two double-effect evaporators were used in series to vaporize water, using heat-carrying oil. Torrefied and pelletized bio-solid was produced at 413 kg/h, comprising 4.4 and 4.8% of water and oil, respectively, and 67% of its mass was used as heat source. The total energy consumption was 1,369 kW, including 93 kW electrical and 1,276 kW thermal energies. The total heat duty was 788 kcal/kg-water.