The drying characteristics of wheat straw in a self-designed pilot-scale cyclone dryer

Biomass is normally a poor thermal conductor with high moisture content. These characteristics not only reduce the calorific value of biomass, but also promote the formation of coke and non-condensable gas during subsequent thermal processing. However, the commercial application of biomass is limited to the high energy and time consumption during drying stage. In this research, a pilot-scale cyclone dryer was designed for efficient drying of biomass and the drying characteristics were explored. Its superiority was revealed via the comparison of two traditional drying methods as blast drying oven and fluidized bed. Results showed that cyclone drying has the highest moisture diffusion coefficient (9.0 x 10(-10) m(2)/s to 1.3 x 10(-9) m(2)/s) and the lowest drying activation energy (18.3 kJ/mol). Its drying time is nearly 10% less than that of fluidized bed drying. Even this value is only about 1/4 of blast drying oven. Experimental results show that most of the free water can be removed in a shorter time in the stage of drying speed reduction in cyclone, especially in the initial stage of drying at the same temperature in the low-temperature zone (60 to 80 celcius). It was found that the cyclone drying technology can dry biomass particles in a short time with low energy consumption.