Solid Biomass Pretreatment Processes

The characteristics of raw biomass usually make necessary the pretreatment of material in order to achieve high energy and high quality biofuels prior to their end use in thermochemical conversion technologies. Pretreatment of solid raw biomass is widely applied to upgrade the properties of solid fuels. This chapter presents the main processes employed in biofuels technologies for solid biomass pretreatment. The densification technologies, namely biomass pelleting and briquetting are introduced and elaborated. A comprehensive reference is also performed for torrefaction, a mild pyrolysis method which is used mainly to improve the properties of solid biofuels, producing mainly biochar, which is a highly valuable product of the biofuels range. Hydrothermal carbonization (HTC), also called wet pyrolysis or wet torrefaction, the exothermic thermal process where hot compressed subcritical water is used to heat the raw biomass under autogenous pressures and relatively low temperatures is also elaborated.