Torrefaction of Biomass to Enhance Fuel Properties

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Acharya, Bimal
Torrefaction is the thermochemical pre-treatment process by partially controlled and isothermal pyrolysis of biomass in minimum oxygen concentration at 200°C-300°C. During the torrefaction, devolatization and carbonization of hemicelluloses and depolymerization and devolatilisation of lignin and cellulose takes place which helps on developing more efficient biofuel products with a uniform feedstock with minimum variability in moisture contents, high energy density, low moisture and oxygen content, hydrophobic. Although biomass is abundant and renewable, its properties pose several challenges during thermal conversion process; hence, limits its direct applications in power plant operations. The main objective of this study is to examine the fuel properties of Poultry Litter, Willow and Oats after torrefaction. The temperature from 200°C to 300°C, oxygen concentration from 0% to 2.4% and residence time from 15 to 45 minutes are varied and observed the mass loss, energy loss and heating values of the torrefied products and observed that torrefied Oats at 300°C for 45 minutes has the highest heating value with 23.56MJ/Kg whereas torrefied Willow and Poultry litter in a similar environment have 20.998MJ/Kg and 12.424 MJ/Kg respectively. There are no significance variations in heating values with the increase of oxygen concentration up to 2.4%. Depending upon the torrefaction environment, 88% of energy yield and 72% of mass yield are observed. Oats shows the fastest mass loss than willow and Poultry Litter above 250°C and 30 minutes residence time. For the hydrophobicity and storage behavior, torrefied at 270°C to 285°C with residence time of 45 minutes shows the optimum for all of the biomass.
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