Caracterização do carvão vegetal produzido em fornos retangulares industriais

Abstract

RESUMO: O objetivo deste estudo foi caracterizar as propriedades do carvão vegetal produzido em fornos retangulares industriais, por meio da análise de componentes principais. Para isto, foram amostrados três estoques industriais de carvão vegetal, provenientes dos Forno I e II, com capacidade volumétrica de 500 e 180m 3 de madeira, respectivamente. Determinaramse as características do carvão vegetal, como granulometria média, teor de finos, densidade a granel e composição química imediata. Foram realizadas as análises descritiva e de componentes principais com o objetivo de avaliar as relações entre as propriedades do carvão vegetal. De forma geral, para ambos os fornos, observou-se que a granulometria média teve uma relação negativa com teor de finos, enquanto a densidade a granel, uma relação positiva. No entanto, a relação entre o carbono fixo e teor de cinzas para o Forno I foi direta, e para o II foi inversa. As propriedades do carvão vegetal dos fornos retangulares, de forma geral, apresentam média assimetria. O carvão vegetal possui alta variabilidade nas suas propriedades, no entanto, é possível, por meio de ajustes operacionais, melhorar a qualidade do carvão para o consumidor final.Palavras-chave: análise de componentes principais; carbono fixo; granulometria média Characterization of charcoal produced in industrial rectangular furnaces ABSTRACT:The objective of this study was to characterize the properties of charcoal produced in industrial rectangular furnaces, using principal components analysis. For this, three industrial stocks of charcoal were sampled from Furnace I and II, with volumetric capacity of 500 and 180m 3 of wood, respectively. The average particle size, fines content, bulk density and proximate composition were determined. Descriptive analysis and principal component analysis were carried out to evaluate the relationships between charcoal properties. In general, for both furnaces, it was found that the average particle size showed a negative relationship with fines content as the bulk density had a positive relationship with the content of fines. However, the relationship between the fixed carbon and ash content for Furnace I was direct, and for Furnace II was inverse. The charcoal properties of the rectangular furnaces, in general, present a medium asymmetry. The charcoal has a high variability in its properties, however, it is possible, by operating adjustments to improve the quality of coal to the consumer.

Carbonization temperature and charcoal properties at different positions in rectangular kiln

“…The produced wood charcoal had an average fixed carbon value equal to 75.39%, and this value was close to that verified by Arruda et al (2011) and Figueiró et al (2019), who evaluated the quality of eucalyptus charcoal produced in rectangular kilns with temperature control. The fixed carbon value found was adequate, as the average percentage for using charcoal as an input for the steel industry should vary between 70 and 75% fixed carbon (Carneiro et al, 2013;Santos et al 2016).…”

“…The average bulk density of charcoal in this study (Table 2) was higher than that observed by Figueiró et al (2019), who found average values ranging from 180 to 205 kg m -3 when characterizing the charcoal properties produced in rectangular industrial kilns. However, this difference can be attributed to the difference in the carbonization conduction or temperature, granulometric distribution and humidity of the analyzed charcoal, as well as the wood used as raw material.…”

“…The average fines production values, charcoal smaller than 9.5 millimeters, was 19.77% with a variation of 27.25% (Table 2). Figueiró et al (2019) determined the properties of charcoal produced in rectangular industrial kilns and found average values of fines equal to 20.75% for a kiln with 500m³ of wood and 23.79% for a kiln of 180m³, presenting an average variation of 40%.…”

“…In this work, the values obtained were close to 20%, and this may be attributed to the unloading the charcoal, which occurs mechanically in rectangular kilns. According to Figueiró et al (2019), greater movement of the charcoal results in more breaks and, consequently, greater fines content. In addition to handling, generation of charcoal fines in masonry furnaces is also affected by the carbonization temperature.…”

“…Brazil is the world's largest producer of wood charcoal and is responsible for 11% of total production in 2018, which accounted roughly for 4.6 million tons with 91% of the product origins being wood from planted forests (IBÁ, 2019). Brazil's position as a leader is due to the use of charcoal as a thermo-reducer input by the steel industry, which provides carbon and energy to reduce iron ore, and it acts as a support structure for the ore load (Figueiró et al, 2019). Additionally, the wood charcoal causes less pollution than the mineral charcoal (Rodrigues & Braghini Júnior, 2019).…”