Biocoque de eucalipto como fonte de energia renovável para uso siderúrgico
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Data
2019-07-19
Autores
Barros, João Lúcio de
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Universidade Estadual Paulista (Unesp)
Resumo
O Brasil se destaca na produção do ferro e aço, e principalmente na utilização de fontes renováveis como insumos energéticos para sua produção. O biocoque possui potencial para utilização de biomassas como insumos energéticos em alto fornos, em substituição aos tradicionais combustíveis fósseis, carvão e coque, porém, ainda é um material pouco conhecido cientificamente. O objetivo foi encontrar os parâmetros adequados para a produção, em escala laboratorial, do biocoque de casca e serragem da madeira de eucalipto. Também verificar suas principais características térmicas e físico-químicas, antes e após a produção do biocoque. Foi usado a casca e serragem de eucalipto para a produção do biocoque. Os materiais passaram por analises de umidade, analise imediata, analise elementar, poder calorífico, densidades, resistência mecânica, estabilidade dimensional, termogravimetria, microscopia MEV, espectroscopia FTIR e EDS, difratometria de raio-x e análises cinética. O biocoque para ambos os materiais foram prensados com força de 10 toneladas sob 180 °C de temperatura por 10 minutos, apresentando características físico-químicas adequadas para o uso. Os biocoques tiveram caracteristicas físicas adequadas a necessidade de uso com alta resistência mecânica, com aproximadamente 10 MPa para ambos os materiais e durabilidade acima de 99 %. A densidade aparente (1.350 kg.m-3) foi aumentada aproximadamente cinco vezes comparado ao valor inicial para o material particulado. Os materiais apresentaram umidade em torno de 8 % e teor de cinzas de aproximadamente 1 %, valores que atendem o mercado e estão próximos ao carvão e coque. O poder calorífico superior e inferior do material foram de respectivamente 19 e 18 kJ.mol-1. A termogravimetria mostrou que os materiais possuem boa estabilidade térmica, iniciando a decomposição na faixa de temperatura entre 250 e 300 °C. Os cálculos cinéticos mostraram que o fator pré-exponencial dos materiais tiveram valores exponenciais elevados sugerindo a alta complexidade do material durante a termoconversão. Os resultados de energia de ativação e energia livre de Gibbs corroboraram para com a interpretação dos demais resultados mostrando a alta demanda energética para a termoconversão do material, sugerindo uma alta resistência e estabilidade térmica, principalmente a temperaturas mais elevadas. O método de Friedman mostrou-se mais sensitivo ao processo sendo mais adequado ao estudo cinético das biomassas estudadas. Os parâmetros encontrados para a produção do biocoque atenderam aos requisitos do produto final. Concluiu-se que os materiais casca e serragem de eucalipto são materiais com potencial técnico viaveis para a produção do biocoque.
Brazil stands out in the production of iron and steel and especially in the use of renewable sources as energy inputs for its production. Biocoque has the potential to use biomass as energy inputs in blast furnaces. It is used to replace traditional fossil fuels (coal and coke) but it is still a relatively unknown material. The objective was to find suitable parameters for the laboratory-scale production of biocoque from bark and sawdust of eucalyptus wood. Also to verify its thermal and physicochemical characteristics, before and after the production of the biocoque. The bark and sawdust of eucalyptus was used for the production of the biocoque. The materials were subject to moisture content, proximate analysis, ultimate analysis, heating value, densities, mechanical resistance, dimensional stability, thermogravimetry, SEM microscopy, FTIR and EDS spectroscopy, X-ray diffractometry and kinetic analysis. The process of the biocoque production were under a load of 10 tons; 180 °C of temperature and kept pressing for 10 minutes. The biocoques had physical characteristics considered high mechanical resistance (10 MPa) for both materials and durability above 99%. The apparent density (1350 kg.m-3) increased approximately five times compared to raw material. The moisture content (8%) and ash content (1%) were considered suitable to the market. The higher and lower heating value of the material were respectively 19 and 18 kJ.mol-1. Thermogravimetry showed that the materials had good thermal stability, initiating the decomposition in the temperature range between 250 and 300 °C. The kinetic calculations showed that the pre-exponential factor had high exponential values suggesting the high complexity of the material during the thermo-conversion. The results of Gibbs energy and free energy showed the high energy demand for thermo-conversion of the material. The Friedman method was more sensitive to the process, being more suitable for the kinetic behavior of the studied biomasses. The results suggested a high resistance and thermal stability of the biocoque. The parameters for biocoque production have met the requirements of the final product. It was concluded that the eucalyptus bark and sawdust materials are materials with technical potential for the production of biocoque.
Brazil stands out in the production of iron and steel and especially in the use of renewable sources as energy inputs for its production. Biocoque has the potential to use biomass as energy inputs in blast furnaces. It is used to replace traditional fossil fuels (coal and coke) but it is still a relatively unknown material. The objective was to find suitable parameters for the laboratory-scale production of biocoque from bark and sawdust of eucalyptus wood. Also to verify its thermal and physicochemical characteristics, before and after the production of the biocoque. The bark and sawdust of eucalyptus was used for the production of the biocoque. The materials were subject to moisture content, proximate analysis, ultimate analysis, heating value, densities, mechanical resistance, dimensional stability, thermogravimetry, SEM microscopy, FTIR and EDS spectroscopy, X-ray diffractometry and kinetic analysis. The process of the biocoque production were under a load of 10 tons; 180 °C of temperature and kept pressing for 10 minutes. The biocoques had physical characteristics considered high mechanical resistance (10 MPa) for both materials and durability above 99%. The apparent density (1350 kg.m-3) increased approximately five times compared to raw material. The moisture content (8%) and ash content (1%) were considered suitable to the market. The higher and lower heating value of the material were respectively 19 and 18 kJ.mol-1. Thermogravimetry showed that the materials had good thermal stability, initiating the decomposition in the temperature range between 250 and 300 °C. The kinetic calculations showed that the pre-exponential factor had high exponential values suggesting the high complexity of the material during the thermo-conversion. The results of Gibbs energy and free energy showed the high energy demand for thermo-conversion of the material. The Friedman method was more sensitive to the process, being more suitable for the kinetic behavior of the studied biomasses. The results suggested a high resistance and thermal stability of the biocoque. The parameters for biocoque production have met the requirements of the final product. It was concluded that the eucalyptus bark and sawdust materials are materials with technical potential for the production of biocoque.
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Serragem, energia de ativação, poder calorífico, reações cinéticas, Sawdust, Bark, Activation energy, Heating value and kinetic reactions, Energia Fontes alternativas, Alternate energy sources, Gerenciamento de resíduos, Waste Managements, Resíduos organicos Reaproveitamento, Organic wastes Recycling