Enhanced drying of water-containing porous aluminum hydroxide particles via a cyclone based on microchannel oscillation

Abstract

Conventional drying methods for water-containing porous particles typically require overcoming the latent heat of water evaporation, rendering them energy intensive. We present a rapid drying process via a cyclone below the boiling point on the basis of high-speed self-rotation and microchannel oscillation of particles. A high-speed camera recorded the particle revolution and self-rotation speeds within the cyclone, which allowed us to calculate the centrifugal acceleration of water in the particle pores, which reached 23,766 m/s² and periodically oscillated. Consequently, water in macropore with diameters larger than 8.1 μm can be separated into microdroplets by cyclones. Various factors influencing the drying efficiency of the cyclone were investigated at the laboratory scale. In experiments conducted with an airflow rate of 75 m³/h, an air temperature of 80°C, and a particle feed rate of 5.4 kg/h, a significant reduction in the water content was observed, with the water content decreasing from 68.2 % to 32.1 % within only 25 s. Compared with traditional evaporative drying, the drying process via a cyclone for aluminum hydroxide with a capacity of 2.4 tons/day saves 2500 tons of steam and 70,000 kW•h of electricity per year, resulting in a cost reduction of 560,000 CNY. These findings suggest that cyclone drying is a highly efficient and cost-effective method for drying water-containing porous particles, with significant implications for energy savings and sustainability in industrial applications.