Finos de carvão vegetal são coprodutos da carbonização da madeira, indesejados por diminuir o rendimento gravimétrico em carvão vegetal. São produzidos devido ao processo de carbonização, durante o armazenamento e transporte do carvão vegetal. A pelletização de finos aumenta a densidade energética, produzindo um combustível homogêneo e com menor teor de umidade, possibilitando a queima em equipamentos com alta eficiência energética, além de propriedades desejáveis em produtos energéticos como alto teor de carbono fixo e baixo teor de umidade. Este estudo avaliou o efeito do teor de umidade e do tempo de secagem na produção de black pellets a partir de finos de carvão vegetal ligados com amido de arroz (Oryza sativa) nas características físico-químicas e mecânicas. Os black pellets foram produzidos utilizando duas proporções de água (10 ou 20%) e tempo de secagem de 4 ou 6 horas. Os black pellets foram avaliados quanto à análise química imediata, composição elementar, teor de umidade, tamanho, densidade aparente, poder calorífico e densidade energética. A adição de água não afetou o teor de voláteis, cinzas e carbono fixo, enquanto o tratamento com adição de 20% de água e quatro horas de secagem apresentou maior teor de umidade (3,34%). A adição de água permitiu melhor condução de calor e disposição das partículas, produzindo pellets com durabilidade superior a 98%. A melhor disposição promovida pela adição de 20% de água também aumentou a densidade dos pellets, resultando em maior densidade energética. Os black pellets podem ser considerados uma boa alternativa para aquecimento residencial, com tratamento T3 (20% de umidade - 4h de secagem) apresentando elevada densidade energética e melhor desempenho em termos de propriedades desejáveis para utilização e comercialização de acordo com a norma EN 14961-6.

Charcoal fines are co-products of the wood carbonization process, unwanted because they reduce the gravimetric yield of the main product, charcoal. It can be produced due to the carbonization process, during the storage and transport of charcoal. Pelletizing charcoal fines increases the energy density of this material, producing a homogeneous fuel with lower moisture content, enabling burning in equipment with high energy efficiency, in addition to desirable properties in energy products such as high fixed carbon content and low moisture content. This study evaluated the effect of moisture content and drying time on the production of black pellets from charcoal fines bound with rice starch (Oryza sativa) on the physicochemical and mechanical characteristics. Black pellets were produced using two proportions of water (10 or 20%) and a drying time of 4 or 6 hours. Black pellets were evaluated for their proximate analysis, elemental composition, moisture content, size, apparent density, calorific value and energy density. The addition of water did not affect the content of volatile matter, ash, and fixed carbon, while the treatment with addition of 20% water and four hours of drying showed a higher moisture content (3.34%). The addition of water allowed for better heat conduction and particle arrangement, producing pellets with a durability greater than 98%. The better arrangement promoted by the addition of 20% water also increased the density of the pellets, resulting in greater energy density. Black pellets can be considered an alternative for residential heating, with T3 treatment (20% - 4h) with a high energy density and better performance in terms of desirable properties for use and commercialization according to the standard EN 14961-6.

ABSTRACT Economic instability scenarios and reduction in charcoal consumption, such as those that occurred in 2009 and 2016, affect production and result in the maintenance of eucalyptus forests and an increase in the rotation age. The objective of this work was to evaluate the quality of wood from four Eucalyptus clones (clones 1, 2, 3, and 4) at the ages of 108 and 120 months and the charcoal produced in a rectangular kiln. We evaluated the heart/sapwood ratio, basic density, dry mass per hectare.year, and chemical composition . The carbonizations were performed in a rectangular kiln (210 m³ of wood). We determined the gravimetric yield and the charcoal properties: density, particle size and percentage of fines, friability index, proximate analysis, and mass of charcoal produced per hectare.year. We verified the significant effect of clones on basic density and dry mass, whose variations were from 494 to 589 kg m-3 and 12.47 to 23.34 ton.ha-1, respectively. The charcoal yield did not differ among clones (34.1%), while the yield of semicarbonized wood varied from 3.2% (clone 4) to 10.7% (clone 3). The particle size of 65% of the charcoal volume of clones 1 and 3 was greater than 30 mm, and 49.5% of clones 2 and 4. We found medium mechanical resistance for charcoal from all four clones. The apparent density ranged from 356 to 458 kg.m-3, with the highest average value for clone 3. We found the highest charcoal production for clones 1 and 2, 7.5 tons per hectare.year. The fixed carbon did not vary among clones (76.92%). The wood properties of the Eucalyptus clones at ages 108 and 120 months are suitable for charcoal production for metallurgical use. Clones 1 (a hybrid of E. urophylla x E. grandis) and 3 (a hybrid of E. urophylla x E. camaldulensis) stood out from the others.

RESUMO Cenários de instabilidade econômica e redução do consumo de carvão vegetal, como as ocorridas em 2009 e 2016, afetam a produção deste insumo, resultando na manutenção das florestas de eucalipto e aumento da idade de corte. O objetivo deste trabalho foi avaliar a qualidade da madeira de quatro clones de Eucalyptus (clones 1, 2, 3 e 4) com idades entre 108 e 120 meses e do carvão vegetal produzido em forno retangular. Para caracterização da madeira, foram avaliadas a relação cerne/alburno, densidade básica, massa seca por hectare.ano e composição química. As carbonizações foram realizadas em forno retangular, com capacidade de 210 m³ de madeira, e determinaram-se o rendimento gravimétrico e as propriedades do carvão vegetal: densidade do carvão vegetal, granulometria e porcentagem de finos, índice de friabilidade, análise imediata, além da massa de carvão produzida por hectare.ano. Verificou-se efeito significativo dos clones na densidade básica e massa seca, com valores de 494 a 589 kg m-3 e 12,47 a 23,34 ton.ha-1, respectivamente. O rendimento médio em carvão vegetal não diferiu entre os clones e foi igual a 34,1%, enquanto o rendimento em atiço variou de 3,2% para o clone 4 a 10,7% para o clone 3. Os clones 1 e 3 apresentaram em média 65% do volume de carvão vegetal na maior faixa granulométrica (>30 mm), enquanto os clones 2 e 4 tiveram 49,5% nessa granulometria. O carvão vegetal dos quatro clones foi de média resistência e a densidade aparente variou de 356 a 458 kg.m-3, com maior valor para o clone 3. Os clones 1 e 2 apresentaram a maior produção de carvão vegetal, 7,5 toneladas por hectare.ano. O carbono fixo não variou entre os clones, apresentando média igual a 76,92%. Os clones de Eucalyptus nas idades de 108 e 120 meses apresentam propriedades da madeira adequadas para a produção de carvão vegetal, alcançando rendimento gravimétrico e qualidade satisfatórios para uso metalúrgico, destacando-se os clones 1 (híbrido de E. urophylla x E. grandis) e 3 (híbrido de E. urophylla x E. camaldulensis).

ABSTRACT Background: The wood heat treatment results in the partial degradation of its chemical constituents, mainly cellulose and hemicellulose, reducing the hygroscopicity of the material. This process improves the dimensional stability and resistance to biodeterioration and worsens the mechanical resistance. This work aimed to evaluate the effect of heat treatment on the physical, anatomical, chemical, and mechanical properties of Fraxinus excelsior wood. In untreated and heat-treated wood, the pH, buffering capacity, basic density, equilibrium moisture content, shrinkage, wood anatomy, thermogravimetric behavior, and chemistry by conventional and FTIR methods were determined. Results: Heat treated wood had lower pH (5.50), equilibrium moisture content (6.26%), shrinkage (7,29%), holocellulose contents (55,96%) and higher buffering capacity (0,479 mmol/L), extractives (8,25%), and lignin contents (35,78%). Heat treatment reduced the pH and increased the buffering capacity of the wood, reduced the holocellulose content, and increased the lignin content, leaving the wood less hygroscopic and reducing its volumetric and linear variation. The process did not change the basic density and fiber length, but it reduced their width, lumen diameter, and wall thickness. The FTIR analysis confirmed the degradation of holocellulose and division of aliphatic side chains in lignin. The maximum dredging range of untreated and heat-treated wood occurred at 350 ºC, and the heat-treated wood had a higher residual mass when subjected to 500 ºC. Conclusion: Heat-treated wood can be indicated for products used in external environments, such as floors, fences, coatings, door and window structures.

ABSTRACT Wood from planted forests is the main input in the charcoal production chain. However, the heterogeneity of charcoal, in terms of its physical, chemical and mechanical properties, and the low yield in production processes is among the main problems faced by industries. To select the best clones for the production of charcoal for steelmaking, the objective of this work was to evaluate the properties of wood, in addition to the yield and quality of charcoal from different genotypes of Eucalyptus and Corymbia. Five clones of Eucalyptus spp., 8 years old and one of Corymbia torelliana x Corymbia citriodora, 4 years old were studied. In the wood were determined the basic density, structural chemical composition, thermogravimetric analysis (TG/DTG), crystallinity index and higher heating value. Carbonizations were carried out in a muffle oven, with a total time of 270 minutes, starting at 150°C and ending at 450°C. The gravimetric yield, apparent density, higher heating value and proximate analysis of charcoal were determined. The wood basic density varied between 477 and 652 kg/m3, with the highest value observed for the Eucalyptus cloeziana clone. This clone also had the highest total lignin content (32.6%), the highest charcoal yield (36.3%) and charcoal with the highest apparent density (466 kg/m3). The two clones of Eucalyptus urophylla had the highest heating value for charcoal, whose mean was 7545 kcal/kg. The clone of Corymbia torelliana x Corymbia citriodora, having an apparent density greater than 500 kg/m3 at 4 years of age, stood out in terms of productivity. All evaluated clones have potential for charcoal production, however, the Eucalyptus cloeziana clone stood out positively, being the most suitable for charcoal production.

RESUMO A madeira oriunda de florestas plantadas é o insumo principal na cadeia produtiva do carvão vegetal. No entanto, a heterogeneidade do carvão vegetal, em termos de suas propriedades físicas, químicas e mecânicas e o baixo rendimento nos processos de produção, está entre os principais problemas enfrentados pelas indústrias. Visando selecionar os melhores clones para a produção de carvão vegetal para uso siderúrgico, o objetivo desse trabalho foi avaliar as propriedades da madeira, além do rendimento e qualidade do carvão vegetal provenientes de diferentes genótipos de Eucalyptus e Corymbia. Foram estudados cinco clones de Eucalyptus spp., com idade de 8 anos e um de Corymbia torelliana x Corymbia citriodora, com idade de 4 anos. Na madeira, determinou-se a densidade básica, composição química estrutural, análise termogravimética (TG/DTG), índice de cristalinidade e poder calorífico superior. Foram realizadas carbonizações em forno mufla, com tempo total de 270 minutos, iniciando em 150°C e finalizando em 450°C. Determinou-se o rendimento gravimétrico, a densidade aparente, o poder calorífico superior e a composição química imediata do carvão vegetal. A densidade básica da madeira variou entre 477 e 652 kg/m3, sendo que o maior valor foi observado para o clone de Eucalyptus cloeziana. Este clone também apresentou o maior teor de lignina total (32,6%), maior rendimento em carvão vegetal (36,3%) e carvão vegetal com maior densidade aparente (466 kg/m3). Os dois clones de Eucalyptus urophylla apresentaram maior poder calorífico superior para o carvão vegetal, cuja média foi 7545 kcal/kg. O clone de Corymbia torelliana x Corymbia citriodora, por ter densidade aparente superior a 500 kg/m3, aos 4 anos de idade, foi o destaque em termos de produtividade. Todos os clones avaliados possuem potencial para a produção de carvão vegetal, porém o clone Eucalyptus cloeziana se destacou positivamente, sendo o mais indicado para a produção de carvão vegetal.

Resumo O objetivo deste trabalho foi selecionar os materiais superiores de Eucalyptus spp. a partir de análises estatísticas univariada e multivariada. Utilizaram-se 25 materiais genéticos de Eucalyptus spp., coletados no município de Itamarandiba, Minas Gerais. Foram determinadas as propriedades da madeira e do carvão vegetal para todos os materiais genéticos, além do rendimento gravimétrico. Os dados foram submetidos ao algoritmo de agrupamento hierárquico Scott-Knott, como análise univariada. Para a realização da abordagem multivariada, utilizou-se uma combinação entre as análises de componentes principais e a análise de agrupamentos hierárquicos. Ambas as análises se mostraram eficientes na seleção de materiais genéticos para a produção de carvão vegetal. De acordo com o teste de Scott-Knott, os materiais genéticos 9 e 21 foram os mais indicados para a produção de carvão vegetal. Por meio das análises multivariadas, os mais indicados foram o 9, 10 e 21. O teste de Scott-Knott permitiu a visualização dos resultados de cada parâmetro de qualidade de forma independente, por outro lado, as ferramentas multivariadas possibilitaram a observação das relações entre as propriedades da madeira e do carvão vegetal.

Abstract The aim of this study was to select superior materials of Eucalyptus spp. using univariate and multivariate statistical analyzes. Twenty-five genetic materials from Eucalyptus spp. collected in Itamarandiba, Minas Gerais were used. The properties of wood and charcoal were determined for all genetic materials, in addition to the gravimetric yield. Data were submitted to Scott-Knott hierarchical clustering algorithm as univariate analysis. For the multivariate approach, a combination between principal component analysis and hierarchical cluster analysis was used. Both analyzes were efficient in the selection of genetic materials for charcoal production. According to the Scott-Knott test, genetic materials 9 and 21 were the most suitable to produce charcoal. By means of the multivariate analyzes the most indicated were 9, 10 and 21. The Scott-Knott test allowed the visualization of the results of each quality parameter independently. On the other hand, the multivariate tools enabled the observation of the relation between the properties of wood and charcoal.

RESUMO A previsão de biomassa de madeira e estoque de carbono em florestas plantadas pode variar devido a limitações associadas à medição de parâmetros. Portanto, reduzir possíveis erros gerados na quantificação de biomassa e estoque de carbono é um passo importante na obtenção de dados confiáveis. O objetivo do estudo foi comparar o uso de metodologias destrutivas e não destrutivas para a previsão de biomassa e estoque de carbono em uma floresta plantada de eucalipto. As análises foram realizadas em 21 árvores e 3 metodologias para estimativa de estoque de carbono foram comparadas. Para a metodologia 1, uma amostra controle foi colhida, seccionada, pesada em campo e o estoque de carbono calculado com base nesses dados. A metodologia 2 também foi destrutiva, pois as árvores foram cortadas, cubadas e o estoque de carbono previsto com base nesses dados. A metodologia 3 foi não destrutiva, pois as árvores foram cubadas com auxílio de um equipamento e o estoque de carbono estimado foi baseado nesses dados. A biomassa e o estoque de carbono foram comparados pelo Teste F e nenhuma diferença estatística foi observada. Os dados foram separados de acordo com as classes diamétricas e comparados pelo teste de Kolmogorov-Smirnov, e novamente não foi observada diferença significativa. Além disso, três equações foram geradas com base no modelo de Schumacher & Hall e comparadas pelo modelo de teste de identidade e não foram observadas diferenças entre as metodologias. Assim, tanto as metodologias não destrutivas quanto as destrutivas aqui avaliadas foram eficazes e apresentaram resultados iguais à amostra controle. Além disso, o uso da metodologia não destrutiva reduz o tempo e o custo destinados à previsão de biomassa e estoque de carbono.

ABSTRACT Predicting wood biomass and carbon stock contents in planted forests can vary due to limitations associated with the measurement of parameters. Therefore, reducing possible errors generated over biomass and carbon stock quantification is an important step in obtaining reliable data. The study aimed to compare the use of destructive and non-destructive methodologies for predicting biomass and carbon stock in a planted Eucalyptus forest. Scaling was performed on 21 trees and 3 methodologies for carbon stock estimation were compared. For methodology 1, a control sample was harvested, sectioned, weighted in the field, and the carbon stock calculated based on these data. Methodology 2 was also destructive, as trees were harvested, scaled and the carbon stock predicted based on these data. Methodology 3 was non-destructive, as trees were scaled upright with the aid of equipment and the predicted carbon stock was based on these data. Biomass and carbon stock were compared by Test F and no statistical difference was observed. The data were separated according to diametric classes and compared by the Kolmogorov-Smirnov test, and again no significant difference was observed. Furthermore, three equations were generated based on the Schumacher & Hall model and compared by the identity test model and no differences between the methodologies were observed. Thus, both nondestructive and destructive methodologies herein evaluated were effective and showed equal results to the control sample. Moreover, the use of the non-destructive methodology reduces time and cost destined to predicting biomass and carbon stock.

ABSTRACT Background: The fibres dimensions vary along a tree trunk, and these variations are related to the apical meristem and vascular cambium activities; understanding these variations would guide the best use of wood. There have been studies on the pattern of fibres dimensions variation along the tree trunk in the radial and longitudinal directions; however, the vast majority do not take into account the structure of the annual growth rings. Hence, this study aimed to obtain the pattern of fibres dimensions variation and their quality indexes along the tree trunk take into account the structure of the annual growth rings. Two Eucalyptus urophylla x Eucalyptus grandis hybrid clones were used in the study. Ten-year-old trees were selected and discs were removed from 13 longitudinal positions. The disks were prepared and the growth rings were subsequently identified and the samples used for maceration were collected. Twenty fibres were measured in the annual growth rings present in each longitudinal position. Results: In the longitudinal direction, within the annual growth rings, the fibre dimensions and their quality indices did not show a well-defined pattern of variation. In the radial direction, the length, cell wall thickness, wall fraction, and Runkel ratio of the fibres tended to increase following the pith-bark direction, while the lumen diameter and flexibility coefficient decreased. Conclusion: Nevertheless, the fibre width and fibre slenderness index did not present a well-defined pattern of variation in the radial direction.

RESUMO Os métodos tradicionais de avaliação econômica de projetos de produção de madeira e carvão vegetal são baseados na análise de indicadores, porém, estão sujeitas a variações de mercado e incertezas. O estudo foiconduzido no município de Lamim-MG, para avaliação da viabilidade econômica na produção de madeira e carvão vegetal com o uso do sistema forno-fornalha, devido à necessidade de se conhecer a viabilidade econômica desse novo sistema produtivo. A análise de sensibilidade utilizando a técnica de Monte Carlo foirealizada nos custos e receitas. O fluxo de caixa para a produção de madeira e de carvão vegetal foielaborado e os seguintes critérios foram utilizados na análise econômica: Valor Presente Líquido (VPL), Razão Benefício Custo (B/C), Valor Periódico Equivalente (VPE) e Taxa Interna de Retorno (TIR). A análise de sensibilidade na produção de madeira e da produção de carvão vegetal foirealizada com o auxílio do software @RISK, de acordo com o parâmetro VPE, que permite comparar projetos com durações diferentes. A produção de madeira foiviável economicamente, com VPL de R$212,68 ha-1 e VPE de R$88,74 ha-1, com custo médio de produção de R$71,37 m3 madeira-1. O valor médio do VPE encontrado na análise de sensibilidade foide R$ 96,82 ha-1. A produção de carvão vegetal foiviável economicamente, com VPL de R$23,41 mdc carvão vegetal-1 e VPE de R$18,57 mdc carvão vegetal-1. O valor médio do VPE encontrado na análise de risco foide R$51,78 mdc carvão vegetal-1. Foi possível concluir que a produção de madeira de eucalipto e de carvão vegetal são viáveis economicamente na região.

ABSTRACT Traditional methods of economic evaluation of wood and charcoal production projects are based on indicators analysis, however, they are subject to market variations and uncertainties. The study was carried out in the city of Lamim, Minas Gerais State, to evaluate the economic viability of wood and charcoal production using the kiln-furnace system, due to the need to know the economic viability of this new production system. Sensitivity analysis using the Monte Carlo technique was performed on costs and revenues. The wood and charcoal production cash flow was elaborated and the following criteria were used in the economic analysis: Net Present Value (NPV), Benefit-Cost Ratio (BCR), Equivalent Periodic Value (EPV), and Internal Return Rate (IRR). The wood and charcoal production sensitivity analysis was carried out using the software @RISK, according to the VPE parameter, which allows comparing projects with different durations. Wood production was economically viable, with NPV of $40.26 ha-1 and EPV of $ 16.80 ha-1, with an average production cost of $13.51 m3 wood-1. The EPV mean value found in the sensitivity analysis was $18.33 ha-1. The charcoal production was economically viable, with NPV of $4.43 mdc charcoal-1 and EPV of $3.52 mdc charcoal-1. The EPV mean value found in the sensitivity analysis was $9.80 mdc charcoal-1. It was possible to conclude that the wood and charcoal production are economically viable in the region.

Resumo O carvão vegetal é um importante insumo na siderurgia nacional e seu uso tem muitas vantagens sobre o carvão mineral e o coque, uma vez que é renovável, menos poluente e com baixos teores de enxofre e fósforo. A partir disso, o objetivo deste trabalho foi avaliar o desempenho do resfriamento artificial do carvão vegetal em forno retangular. Para isso, foi avaliada a influência da variação da velocidade do escoamento de gás pelo leito poroso de carvão na qualidade final do produto. Foram utilizadas quatro velocidades de escoamento, em 3 repetições, totalizando 12 ensaios de carbonizações da madeira em um forno retangular. O uso do trocador de calor proporcionou redução no tempo de resfriamento de 76 para 28 horas. A maior redução no tempo de resfriamento foi obtida com a menor velocidade de escoamento. Nas maiores velocidades ocorreu queima de uma parte do carvão na seção de saída dos gases do forno, o que provocou aumento no tempo de resfriamento. No entanto, verificou-se que essas queimas parciais não causaram diferença significativa no rendimento gravimétrico em relação à testemunha. Para as velocidades adotadas, verificou-se que não houve diferença significativa entre os tratamentos e a testemunha nos parâmetros de qualidade do carvão. Portanto, no dimensionamento de trocadores de calor, deve-se considerar a diferença de pressão entre as aberturas de sucção e injeção dos gases no forno para minimizar a infiltração de ar no forno.

Abstract Charcoal is an important material in the national steelmaking industry and its use has many benefits over coal and coke, since it is renewable, less polluting and with lower contents of sulfur and phosphorus. The aim of this study was to evaluate the performance of the artificial cooling of the charcoal in a rectangular kiln. It was evaluated the influence of the variation of the velocity of the gas flow through the porous bed of charcoal in the final quality of the product. Four flow velocities were used, in three repetitions, totalizing 12 carbonization tests in a rectangular kiln. The used of heat exchanger provided a reduction from 76 to 28 hours in the cooling time. The highest reduction in cooling time was obtained with lower flow velocity. It was observed that, at higher velocities, part of the charcoal closed to the exhaust section of the kiln was burned, which resulted in an increase in the cooling time. However, these partial burns did not cause the significant difference in gravimetric yield in relation to the control. For the velocities adopted, it was verified that there was no significant difference between the treatments and the control in the quality parameters of the charcoal. Therefore, for the dimensioning of heat exchangers, the pressure difference between the suction openings and the gas injection should be considered to minimize the infiltration of air into the kiln.

Abstract: Thermal treatments have the effect of reducing the hygroscopicity and improving the resistance to microbiological attack of wood by the degradation of its chemical constituents. During the treatments, the mass of the wood is reduced, a factor that can affect the quality of the materials according to their use. The objective was to verify the effect of the thermal treatment variables on the thermogravimetric properties and the chemical composition of Eucalyptus grandis. The treatments were carried out in a vacuum oven with three atmosphere conditions - vacuum; N2; vacuum+N2 at temperatures of 140, 180 and 220 °C for 6 hours. It was observed that the mass loss during treatments differed only according to the temperatures used. The extractive content, total lignin and holocellulose presented significant changes only at 220°C in all three atmospheres. In the thermogravimetric analysis, the greatest value of residual mass was found in the treatment that used nitrogen and 220 °C, thus demonstrating that this treatment was more invasive, leading to the conclusion that the vacuum application can help to reduce the degradation of the constituents of the eucalypt wood. Wood, which can lead to the production of thermally treated wood without great losses in the mechanical properties.

ABSTRACT The knowledge of the physical and thermal properties of eucalyptus charcoal is of fundamental importance in the design of equipment and development of cooling technologies. However, literature about physical properties for eucalyptus wood charcoal is largely unavailable, especially the thermal and aerodynamic properties, for the same material. The aim of this study was to evaluate the physical properties of eucalyptus charcoal: apparent and bulk density, pressure drop, porosity, thermal conductivity and specific heat to support the design of production and cooling systems using heat exchangers. It was found that the pressure drop could be expressed according Forchheimer’s law and logarithmical empirical models, resulting in R2 above 0.95. The apparent and bulk densities were measured as 344.6 ± 17.6 and 155.3 ± 4.1 kg.m-3, respectively, and the charcoal porosity was 54.8 ± 2%. In the investigation of flow in porous charcoal media, the pressure gradient is proportional to the increase of the superficial airflow velocity and is dependent on the charcoal bed height for low airflows and lower bed heights. However, the gradient was independent of bed height on all tests with columns larger or equal to 0.80 m. The thermal conductivity and specific heat were 0.030 ± 0.0027 W m-1.K-1 and 1017 ± 74 J.kg-1.K-1, respectively.

Abstract The charcoal production when performed in woods with high moisture content negatively impacts the pyrolysis and causes an increase of greenhouse emissions. The aim of this study was to investigate the effects of moisture on the production and quality of charcoal for the pig iron industry. The slow pyrolysis of Eucalyptus sp. was carried out in four different wood moistures, 0, 20, 40 and 60% (dry base). The charcoal and gas yield decreased according to the increase of wood moisture. On the other hand, the bio-oil yield and charcoal friability increased along with the moisture content. The proximate analysis, bulk density and higher heating value of the charcoal were not influenced by the moisture content. The use of wood with moisture content below 20% in the production of charcoal is an alternative to improve productivity, contributing for the economic sustanainability of this sector.

RESUMO Este trabalho analisou a viabilidade econômica de quatro sistemas produtivos de carvão vegetal no estado de Minas Gerais, sendo eles: fornos-fornalha, rabo-quente, encosta e superfície. Os sistemas avaliados foram estimados para uma capacidade produtiva aproximada de 100 metros cúbicos de carvão vegetal por mês. Os custos de implantação, manutenção e os parâmetros produtivos foram obtidos na literatura e junto a produtores locais de Lamim (MG), polo produtivo no estado, durante o ano de 2018. Não foram considerados os custos silviculturais, apenas o valor da compra de madeira. Para a avaliação econômica, foram analisados o Valor Presente Líquido (VPL), a Taxa Interna de Retorno Modificada (MTIR), o Payback, o capex e o opex, além de se avaliar a sensibilidade dos sistemas frente a flutuações de preço e rendimento do carvão vegetal. Os principais resultados demonstraram que todos os sistemas foram viáveis economicamente pelo critério do VPL; apenas o sistema rabo-quente não foi viável pelo critério da MTIR; o sistema fornos-fornalha apresentou os melhores resultados econômicos, com maior capacidade de geração de receita líquida e de fluxo de caixa livre, também apresentando o menor custo operacional. Este sistema produtivo ainda demonstrou menor sensibilidade com relação às flutuações do preço de venda do carvão vegetal e da redução de seu rendimento em carvão vegetal. Dado o fato, sua inserção pode ser um atrativo para a realidade produtiva de pequenos e médios produtores. Além disso, a possibilidade da venda da moinha de carvão resultou em melhorias nos indicadores econômicos, principalmente para os sistemas produtivos tradicionais: fornos rabo-quente e de encosta.

ABSTRACT This work analyzed the economic viability of four charcoal productive systems from Minas Gerais state, namely: fornos-fornalha, rabo-quente, encosta and superfície. The evaluated systems have an estimated productive capacity of about 100 cubic meters of charcoal per month. Implementation and maintenance expenses and productive parameters were obtained in the literature and from local producers of Lamim (MG), a productive center in the state, during the year of 2018. Silvicultural costs were not considered, only the wood purchase. For the economic evaluation, Net Present Value (NPV), Modified Internal Rate of Return (MIRR), Payback, capex and opex were analyzed, and it was also evaluated the systems’ economic sensitivity to charcoal price and gravimetric yield variations. The main results showed that all the systems were economically viable by NPV criteria; only rabo-quente system was not viable by MIRR criteria; fornos-fornalha system presented the best economic results, greater capacity of net revenues and free cash flow generation, and lower operational expenses. This productive system was also less sensitive to charcoal price fluctuations and to its charcoal yield reduction. Given this fact, its insertion may be attractive in the productive reality of small and medium producers. In addition, the possibility of selling charcoal fines resulted in improvements in economic indicators, especially for traditional production systems: rabo-quente and encosta.

Abstract Our study aims to determine the energetic quality of residues from the manufacturing of jatropha and eucalyptus, as well as to evaluate the physical properties of the briquettes made with different proportions of these biomasses. The following proportions were used for this study: 100% eucalyptus; 75% eucalyptus; 50% jatropha and 50% eucalyptus; 75% jatropha; and 100% jatropha. The apparent density of the residues, the immediate chemical product, the highest calorific value (HCV), the apparent density, the energy density, the usable calorific value (UCV), the lowest calorific value (LCV), the breaking strength of the briquettes (FR) and the hydroscopic moisture balance (HMB) were verified. Although the energetic characteristics of the jatropha residues are not superior to those of eucalyptus, this biomass adds favorable mechanical characteristics to the briquettes comprised of greater proportions of jatropha to eucalyptus, guaranteeing the energetic properties of the briquette, as well as reducing the production cost.

Abstract: Brazilian productivity of eucalyptus trees is one of the highest in the world, and it has sustainable and viable conditions to supply the demand for woody biomass in a large quantity and diversity. This favorable situation makes Brazil one of the countries with the greatest potential for the production development of torrefied woody biomass on a commercial scale. Torrefaction is a mild pyrolysis applied to increase the energy quality of the feedstock. The aim of this study was to evaluate the Brazilian potential of woody biomass torrefaction for energy purposes. An experimental study was performed evaluating this thermal treatment of eucalyptus wood chips on a semi-continuous screw reactor developed by a Brazilian university. The results showed the increases in the energy quality of eucalyptus wood chips as a function of torrefaction temperature and time. This thermal treatment was technically feasible for the hygroscopicity reduction and the increases of fixed carbon and calorific values of the woody biomass.