Oxidative Torrefaction of Paddy Straw in a Continuous Reactor

Torrefaction uses heat in a controlled reactor to enhance the qualities of raw biomass, which has limited applications. Torrefied biomass has superior qualities over raw biomass, making it an effective eco-friendly product. Paddy straw has more hemicellulose than softwood, making it a strong candidate for torrefaction. Paddy straw and stubble burning emits trace gases and particulate matter (PM10 and PM2.5), which harm the environment and human health. In this research, paddy straw samples from nearby agricultural fields are torrefied in an auger-based continuous reactor under the oxidative conditions. The reactor is operated at varying residence durations (15–30 min) and air-biomass equivalence ratios (ER) to improve production and quality. The physical and chemical properties of raw and torrefied biomass are evaluated and compared. The pH of raw biomass is found to improve by about 0.9 units, EC increased by about 5 times, and calorific value increased by about 1.3 times, upon torrefaction. This study is conducive to establishing the use of oxidative torrefaction as a sustainable technology for the management of agro-waste.