Low-Temperature Rapid Drying of Viscous Sludge Via Non-Phase Change Based on Particle High-Speed Self-Rotation and Medium Dispersion in Cyclone

• Drying technology for viscous sludge with high moisture content was developed. • Dispersed phase medium improved the dispersibility of viscous sludge. • Efficient drying was achieved at low temperature (<100 °C) in mere seconds. • The sludge moisture removal was mainly in the form of non-phase change. • Non-phase change significantly reduced the energy consumption of drying. Drying operations are of grave importance to realize the reduction and utilization of sewage sludge resources, but the conventional thermal evaporation drying (TED) technology faces challenges due to the need for a large amount of thermal energy to conquer the phase-change latent heat of moisture. Herein, we report a non-phase change technology based on particle high-speed self-rotation in a cyclone for fast, low-temperature drying of viscous sludge with high moisture contents. Dispersed phase medium (DPM) is introduced into the cyclone self-rotation drying (CSRD) reactor to enhance the dispersion of the viscous sludge. The effects of carrier gas temperature, feeding rate, size, and proportion of DPM particles in the drying process are systematically examined. Under optimal operating conditions, the weighted content of moisture in the viscous sludge could be reduced from 80% to 15.01% in less than 5 s, achieving a high drying efficiency of 95.79%. Theoretical calculations also reveal that 89.26% of the moisture is removed through a phase change pathway, contributing to a 522-fold increase in the drying rate of CSRD compared to TED technology. This investigation presents a sustainable effective approach for high moisture viscous sludge treatment with low energy consumption and carbon emissions.