Thermochemical Characterization of Casamance Biomass Residues for Production of Combustibles Briquettes

The development of alternatives energies illustrates the common interest of all countries in reducing greenhouse gas emissions and combating climate change. Thermochemical treatment of municipal solid waste, agricultural and forestry wastes is a major challenge for this XXIst century to replace petroleum fuels. Thermogravimetric analysis (TGA) makes it possible to elucidate the thermal behavior of Casamance (Senegal) biomass residues, mass losses and decomposition rate, under inert (N2) atmosphere and oxidizing (O2) atmosphere. Carbonization and briquetting techniques of these various residues encountered in this part of Senegal country, by densification in order to produce fuel briquettes (call biochars) will be used to improve stoves for cooking. Samples used in this study are peanuts shells (PNS), cashew nut shells (CNS), palm nut shells (PLS) and millet stems (MS). Elemental and approximate analyses make it possible to determine the CHNSO* composition, volatile matter, fixed carbon and ashes content of the samples used. Higher heating values (HHV) of the former residues are ranging from 28.60 MJ·kg-1, 26.51 MJ·kg-1, 29.69 MJ·kg-1 and 24.93 MJ·kg-1 respectively. The chars are obtained by slow pyrolysis with a heating rate of 5°C·min-1 from ambient temperature up to 800°C under inert atmosphere. The morphology of the samples is different for the four biomasses studied, from biomass in the form of wood fibers to a more compact biomass. The parietal composition of different samples presented was determined by Van Soest method using neutral detergents (NDS), acid detergent (ADS) and sulfuric acid (H2SO4, 72%); to solubilize successively extractable, hemicellulose and cellulose respectively; lignin was obtained by balance (Table 2). The samples show a high level of cellulose, this pseudo-component is very rich in carbon directly linked to the calorific value, whose values vary from 32.35%; 24.20%; 34.94% and 39.67% for PNS, PLS, CNS and MS respectively.