Thermogravimetric analysis for characterization of the pellets produced with different forest and agricultural residues

Abstract

The pelleting of forest and agricultural materials, mainly because many residues from both industries can be used in this process, has been an alternative in obtaining added value products to energy generation. Thus, the aim of this study was to evaluate the energy quality of the pellets produced from forest and agricultural residues as raw materials and to verify the utility of the thermogravimetric analysis (TGA) and the differential thermogravimetric analysis (DTG) in characterizing the behavior of the pellets during the combustion process. Four residues were used: (1) Pinus spp. woodchips, (2) apple pruning residues, (3) aciculated dry branches of Araucaria angustifolia and (4) A. angustifolia empty-seeds. Chemical composition of the raw materials was determined and the physical and energetic properties of the pellets were analysed. Plus, the proximate analysis of the pellets was carried out. The samples were submitted to TGA with a heating rate of 20ºC min-1 from room temperature to 1000ºC, in a N2 atmosphere. The variation of chemical composition of each residue was determinant in the characterization of each stage of the thermal degradation. Stages and events of the degradation were closely linked to the chemical and energetic nature of the samples. Use of TGA to characterize the thermal degradation of the pellets produced with different forest and agricultural residues was demonstrated as an efficient technique to quantify and qualify the events that occurred in each stage of the combustion of these biofuels.

Production of Wood Pellets from Poplar Trees Managed as Coppices with Different Harvesting Cycles

“…In this perspective, many resources and research activities are now focused on the exploitation of agricultural by-products or energy grasses. However, several studies carried out show problems of low durability of pellets produced from cereal residues [66], high ash content over 3.5%, 5.5% and 6.5% for miscanthus, rape straw and wheat straw respectively [58], 2.27% and 4.2% for apple pruning [67] and vineyard pruning [68].…”

High density polyethylene matrix composite as reinforcing agent in medium density fiberboards

“…Thermal degradation can be distinguished in three main stages. 23 The first stage is related to drying, second stage is related to active pyrolysis and the third stage is related to passive pyrolysis, highlighting that these stages may vary its temperature ranges, depending on the chemical composition of the lignocellulosic material analysed. Hemicellulose and cellulose decompose between 150 C and 350 C, while lignin decomposes between 250 C and 500 C. Also, it is stated that polyethylene has its main decomposition temperature at 517 C, which is related to the result found in these analyses.…”

Desempenho mecânico e durabilidade de argamassas contendo adições de resíduos de carvão vegetal amazônico

“…Analisando os dados da DTG, é possível verificar que na rampa de 800-1000 °C, quando se dão as reações de gasificação da biomassa, ficou registrada uma perda de massa de 4,34%. Sendo as taxas dos 200 °C iniciais e finais equivalentes, em termos de perdas de massa, resta que a faixa central do intervalo (200-600° C) corresponderá aos eventos de carbonização remanescente da matéria orgânica [43]; já na faixa #3 ocorre o pico a 686,67 °C, atingindo temperaturas iguais e acima de 800 °C, onde há perda de água pela condensação de grupos OH [39] e se formam compostos gasosos como CO, CO 2 , além de outros compostos óxidos ou carbonáticos de Mg e Ca [33,40].…”

“…Como já mencionado (2.1), sendo os resíduos de espécies mistas, implica que cada espécie possui ponto de decomposição térmica diferente [43], o que ajuda a explicar a presença da matéria orgânica não queimada. Cabe ressaltar ainda que as CG, como utilizadas neste estudo, são geradas em temperatura máxima de ~500 °C [32].…”