Essential basics on biomass torrefaction, densification and utilization

Torrefaction and densification are crucial steps in upgrading biomass as feedstock for energy generation and metallurgical applications. This paper attempts to discuss essential basics on biomass torrefaction and densification, which can propel developing nation to take full advantage of them. The most promising clean energy sources that have found applications in various areas are biomass materials, that is, both the lignocellulosic and non-lignocellulosic. However, high moisture contents, low energy density, hydrophilic nature, poor storage and handling properties are the major drawbacks limiting its usefulness. Therefore, torrefaction as one of the major thermal pre-treatment processes to upgrade biomass in terms of improved energy density, hydrophobic, moisture content and grindability has been discussed. The influence of temperature, residence time, particle sizes and gas flow rates on the properties of torrefied biomass has also been discussed. The advantages and disadvantages of various torrefaction technologies have also been highlighted. The possible areas of application of torrefied biomass especially densification into pellets and briquettes alongside the equipment required for it have been reviewed in this paper. The torrefied biomass can be deployed in the metallurgical industries as reducing agent in the development of sponge iron from iron ores of various grade including lean ones. The information gathered in this paper from peer-reviewed articles will reduce the burden of seeking to understand the preliminaries of torrefaction process and its importance.