Drying efficiency and product quality of biomass drying: a review

Drying is an energy-intensive pretreatment process of biomass for production of biofuels by thermo-chemical conversion. The efficiency and quality during biomass drying have a significant impact on the economy and sustainability of bioenergy plants. In this review, recent development of conventional dryers, including rotary drum dryer, fluidized bed dryer, pneumatic dryer, agitated drum dryer and fixed or moving bed dryer were described. Progress in the study of advanced drying technologies, such as solar drying, microwave-drying and far-infrared drying in laboratory and pilot-plant scale were summarized as well. In order to reduce the energy consumption of drying system, multistage drying, self-heat recuperation and process integration were introduced in the bioenergy plant. Theoretical performance of these energy-saving processes is represented in this review, along with some experimental findings in the pilot plants.