Avaliação da combustão de um resíduo da colheita do milho e obtenção do poder calorífico por diferentes metodologias

Abstract

The environmental concern about the use of non-renewable energy motivates the creation of new research that allows a more sustainable generation. In this context, lignocellulosic biomass such as agro-industrial residues can be used to generate clean thermal energy with less emission of polluting gases. In this work, the residue from the corn harvest (RM) was used for the study, consisting mainly of corn straw and cob. Several characterization analyzes were carried out and compared with values found in the literature. The focus was given to obtaining the calorific value of the residue by different methods, as it is one of the most important parameters to measure the efficiency of a solid fuel. The calorific value was obtained by means of a bomb calorimeter as an exact parameter for later comparison, and the value of 16.08 MJ/kg was obtained. Several empirical correlations were also used to find this parameter, obtaining an average value of 17.74 MJ/kg. Also, the heat of combustion was evaluated, and correlated with the calorific value, through the integration of the differential scanning calorimetry (DSC) curve obtained by thermogravimetry equipment. The value found by this methodology is 14.00 ± 0.03 MJ/kg, lower than that obtained by bomb calorimetry or by empirical correlations. For the thermogravimetric analysis, synthetic air was used with a gas flow of 100mL/min and a heating rate of 10 °C/min, starting at room temperature up to 900 °C. The RM combustion profile was evaluated from thermogravimetry (TG), derivative thermogravimetry (DTG) and DSC curves. The results of the characterization analyzes, proximate and elemental, demonstrate that the RM presented low moisture (5.72%) and an adequate fixed carbon (CF) value (18.53%), in addition to a high carbon content (44.64%), a low sulfur (0%) and nitrogen (0.63%) contents. These parameters, together with the results of the other analyzes indicate that this residue has the potential to be used for the generation of clean thermal energy.