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Thermogravimetric signals of hemicellulose and lignin were found to subside due to the binderless briquetting of soybean crop residue. Minor but distinct thermogravimetric signals of secondary charring reactions were observed in raw crop residue and its briquetted biofuel. The bio-component related kinetics was evaluated using the Kissinger method. Activation energy level of intrinsic cellulosic biopolymer was found higher in briquette than that level in crop residue. The activation energy profile with respect to conversion fraction for raw residue and its briquette was analyzed by the Kissinger eAkahiraeSunose method. The activation energy profile of briquette was superior to raw residue of soybean crop showing the better thermal stability in briquetted biofuel, highlighting the benefits of briquetting process. In addition to the physico-chemical transformations occurred in lignin, the hemicellulose and cellulose related transitions were also expected to play positive role for briquetting. © 2015 Elsevier Ltd. Source

Gangil S.,Central Institute of Agricultural Engineering
Renewable Energy | Year: 2015

The paper proves that briquettes of lignocellulosic crop residues have higher activation energy levels of intrinsic biopolymers as compared to these energy levels in wood, especially in context with the hemicellulosic and cellulosic segment. Binderless briquettes made of residues from pigeon pea and soybean crops were analyzed in comparison with wood. Thermal decompositions of these biofuels were experimented by thermogravimetry under pyrolysis environment and the transitions of the thermogravimetric signals were explained. Popular isoconversional kinetics method, namely integral Ozawa-Flynn-Wall was used to evaluate and compare the activation energies. Kinetics analyzed that wood was thermally weaker than the briquettes. © 2014 Elsevier Ltd. Source

Gangil S.,Central Institute of Agricultural Engineering
Cellulose | Year: 2014

Distinct splitting of the cellulosic polymer signal was seen in thermogravimetric analysis of cashew shell (CS). The splitting was more pronounced in CS as compared to cashew shell cake. The splitting of cellulosic polymer peaks was ascribed to cellulosic depolymerization occurring in two phases during thermal degradation of CS. Three protective tissue configurations of CS was considered responsible for this phenomenon. Kinetics were compared by using two model free isoconversional methods, namely the Friedman and Ozawa-Flynn-Wall. © 2014 Springer Science+Business Media Dordrecht. Source

Gangil S.,Central Institute of Agricultural Engineering
Environmental Engineering Science | Year: 2014

Thermogravimetric degradation of two kinds of char obtained from two different types of systems, confined and unconfined, was studied. In a confined system, charring was accomplished in a closed chamber in which vapors produced during the charring process were captured within the system and were forced to condense on the char being produced. In the unconfined charring system, a passage was available for the escape of gaseous substances evolved during the charring process; the presence of condensed volatiles in produced char was low. Using thermogravimetric analysis, differences between chars produced in these two systems were studied and it was proved that the char from the unconfined system showed a superior profile of apparent activation energy as compared with the char from the confined system due to higher presence of condensed vapors of volatiles in the char produced in confined conditions. A first-order derivative of thermogram of the char generated in the unconfined system showed a broad peak, at higher temperature segments, ascribed to the thermal decomposition of heavier volatiles and lignin. Activation energies for both types of char were determined and compared using the Coats-Redfern method. Char obtained from the unconfined system had higher thermal stability. This article recommends that for generation of more thermally stable char, unconfined charring chambers should be preferred. A new direct and simple method was used in this article to define the accelerating or retarding nature of thermal decomposition process using segmental analysis of conversion fraction. © 2014 Mary Ann Liebert, Inc. Source

Gangil S.,Central Institute of Agricultural Engineering
Energy and Fuels | Year: 2014

The consolidation of different polymeric bioconstituents was clearly observed in briquetted biofuel produced from pigeon pea crop residues. Critical thermogravimetric diagnosis showed that the scattering of tail end segments of thermograms taken at different heating rates was remarkably low in briquetted biofuel as compared to the scattering in raw material. The consolidation of polymeric cellulose and lignin was discussed and explained. Kinetics was evaluated using isoconversional integral Ozawa-Flynn-Wall method. The activation energy profile of briquetted biofuel dominated over the raw pigeon pea stalks showing higher thermal stability, which was evidence, positive toward the consolidation of intrinsic biopolymers due to briquetting process. © 2014 American Chemical Society. Source

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