Cyclone Rotational Drying of Lignite Based on Particle High-Speed Self-Rotation: Lower Carrier Gas Temperature and Shorter Residence Time

Abstract

The high moisture content of lignite raw materials leads to its low combustion efficiency and large CO 2 emissions. Therefore, the drying of lignite are the keys to achieving efficient and clean utilization, and further realizing energy-saving and emission-reduction. In this study, based on coupling centrifugal effect of high-speed self-rotation and revolution of particles in cyclone, low-energy consumption and high-efficiency lignite cyclone rotational drying was realized at a low carrier gas temperature (lower than 100°C) and in a short residence time (less than 10 s). The influence of operating parameters and structure parameters on lignite drying efficiency were investigated, when carrier gas temperature was 80 °C, the moisture content of lignite can be reduced from 45.1% to 15.2% after single-stage cyclone drying in a 75 mm diameter cyclone. When the diameter of the cyclone was expanded to 100 mm, the single-stage dehydration efficiency can be increased to 75.8%. Compared with the fixed-bed evaporative drying, the cyclone rotational drying can increase the drying rate and reduce the drying time and energy consumption. It is revealed that the cyclone rotational drying method provides a new idea for the lignite drying technology, and can serve as guidance for industrial applications.