Aproveitamento da biomassa florestal na fabricação de briquetes

Abstract

RESUMO A importância do emprego de fontes alternativas de energia, que sejam renováveis e provoquem menores danos ao meio ambiente, como menor poluição atmosférica e estabilidade do ciclo do carbono, traz em destaque a biomassa florestal. Nesse contexto, avaliou-se a produção de briquetes, produzidos a partir de resíduos florestais encontrados nas diversas fases de produção das fábricas de celulose, os quais foram analisados quimicamente, bem como suas propriedades físicas e mecânicas. Foram realizados dez tratamentos a partir de quatro classes de resíduos amostrados, utilizando delineamento estatístico inteiramente casualizado (DIC), com 10 repetições por tratamento. Para a análise estatística, realizou-se teste Tukey de comparação de médias e análise de componentes principais para explicar a estrutura da variância. Os tratamentos 4 e 10 apresentaram maior poder calorífico devido ao seu maior percentual de lignina, bem como obtiveram os melhores resultados de densidade energética. Quanto a densidade e a resistência mecânica, os valores encontrados foram adequados e condizentes aos citados na literatura, sendo que a última variável não diferiu estatisticamente entre os tratamentos. A análise dos componentes principais foi adequada, sendo os teores de extrativos, umidade, lignina, e a densidade energética as variáveis mais importantes na análise, com os mais elevados coeficientes da componente principal 1, a qual representa 70,9% da variância total explicada. O tratamento 4, contendo apenas casca de Pinus taeda, se destacou pelas suas melhores características para energia.

Technical Feasibility Study of Orange Wood Residues (Citrus sinensis) for Bioenergy Generation

“…However, as a by-product of burning large amounts of biomass, ash can be used in the production of silicon carbide, pure silica, mortars and alkaline activators, among others [69][70][71][72]. The values found in compositions 100T and 90T10B are in accordance with the literature with regard to the amount of ash that biomass can present to be used energetically [56,73], except for composition 100B, although the bark can be used in blends [39,50]. The ash contents found in 100T and 90T10B were lower compared to those obtained by [30], which, using the trunk of the orange tree that was aged less than the present study, obtained an ash content of 2.8%, which is expected for tree age according to studies by [32,74].…”

“…The UHV found in 100B can be considered as expected, since this composition was the one that presented a high ash content and extractives, in addition to lower levels of lignin and holocellulose, factors that directly influence the energy value of the material [50,58,77,89]. The data obtained in this study for the compositions containing the trunk of the orange tree are potential sources of energy use in relation to various biomasses, as indicated in the works of [39], who found HHV values in the range of 17.35-19.39 MJ.kg −1 using ten different types of biomass, as well as in [59], who obtained the HHV of 19.6 MJ.kg −1 using açaí seeds, [55], who, using sugarcane bagasse, obtained 18.5 MJ.kg −1 , and [90], who obtained 18.2 MJ.kg −1 , in addition to higher values as in [87], who, using canjiqueira and cambará, obtained 20.07 and 19.54 MJ.kg −1 , respectively.…”

“…As for the ash content, in the material 100T, it was 1.11%, and in 90T10B, it was 1.69%, demonstrating that there was no significant influence of the 10% of the bark. The highest value obtained was in 100B, at 9.33%; this value is high and expected for bark [39,50,58]. Ash has a very complex nature, and in cases of high contents, biomass is not desirable in terms of bioenergy.…”

“…However, there is a positive relationship between extractive content and calorific value [36,37]. The most volatile extractives and low molecular mass are degraded more quickly with an increasing temperature [38], which contributes to burning in order to optimize the combustion of the material [39]. Extractives can also be formed by breaking the hemicellulose chains, giving these new compounds higher degradation temperatures [40][41][42].…”

“…Refs. [39,43] describe in their studies that extractive contents in the range of 10-25% are configured as having an attractive and appropriate chemical characteristic for burning. However, these values are high compared to compositions 100T and 90L10B.…”