Physical and mechanical properties of heat treated wood from Aspidosperma populifolium, Dipteryx odorata and Mimosa scabrella

Heat treatment improves some wood properties namely: equilibrium moisture, dimensional stability and durability and mechanical properties. In this study, the heat treatment was applied to woods of three natural species from Brazil: Aspidosperma populifolium (peroba mica), Dipteryx odorata (cumaru) and Mimosa scabrella (bracatinga). The woods were heated in an oven under vacuum and under nitrogen, at 180, 200, and 220°C for one hour. The untreated and heat-treated woods were characterized in relation to equilibrium moisture content, basic density, shrinkage, Janka hardness, and bending MOR and MOE according to NBR 7190 standards. All the thermal rectified woods showed a reduction in the hygroscopic equilibrium content, especially when the heating was under vacuum from 13-15% in the untreated woods to 1-3% for vacuum treatment at 220 °C. The dimensional stability was improved to only a small extent e.g. volumetric shrinkage tended to decrease with increasing temperature. The mechanical properties were affected differently for the three wood species. Heat-treated cumarushowed increased Janka hardness, MOR and MOE; and peroba mica increased MOR and MOE but not Janka hardness; while bracatinga was less influenced by the heat treatmentinfo:eu-repo/semantics/publishedVersio

Potential of mild torrefaction for upgrading the wood energy value of different Eucalyptus species

Torrefaction is a promising pre-treatment for improving the fuel quality of biomass. This study examined the effect of a mild torrefaction (from 160 to 230 C) on the heating value, elemental composition, and thermogravimetric analysis of wood from eight Eucalyptus species (E. botryoides Sm., E. globulus Labill., E. grandis W.Hill ex Maiden, E. maculata (Hook.) K.D. Hill & L.A.S.Johnson, E. propinqua Maiden Deane, E. rudis Endl., E. saligna Sm., and E. viminalis Labill.). The higher heating values (HHV) increased from the initial average of 19 MJ kg1 to 21 MJ kg1 in the torrefied samples. The carbon content increased from 48.2% to 53.3% and the C/O ratio from 1.08 to 1.35. The torrefied wood samples showed more thermal stability with a shift of the mass loss peaks to higher temperatures and a higher residual mass at 450 C of 36%, in comparison to 30% of the untreated samples. Torrefaction concentrated the biomass samples in the more energetic and thermal resistant components and decreased their sulfur and chlorine content, leading to a better combustion performance. The wood of the eight Eucalyptus species had a similar behavior and showed quality improvement. Therefore, torrefaction showed potential as a pre-treatment for eucalyptus biomass fuel improvementinfo:eu-repo/semantics/publishedVersio

Computational modeling of biosludge drying

Considerable increases in industrial and urban wastewater sludge generation in recent years require proper treatment, such as thermal drying, and disposal. The sludge drying is a complex process involving simultaneous and coupled heat and mass transfer, which can be modeled by taking into account mass and heat balances, and assuming that water diffuses according to kinetic laws. This research implemented a simulation model for biosludge drying processes to predict the temperature and moisture distribution inside the biosludge, using the COMSOL Multiphysics® simulation program v5.2. A parametric analysis was carried out to determine the effect of initial moisture content on biosludge final temperature and moisture reduction. The simulated temperature and moisture content were experimentally validated and good agreement was observed between the simulation and experimental results. This model is a useful tool to optimize the drying process and develop better strategies for the control of the system

Aplicação de análises estatísticas univariada e multivariada na seleção clonal de Eucalyptus spp. para a produção de carvão vegetal

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.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

Utilização de resíduos de coco (Cocos nucifera) carbonizado para a produção de briquetes

O presente trabalho teve como objetivo produzir briquetes com finos de carvão de resíduos de coco e avaliar a qualidade dos briquetes. Cascas de coco foram coletadas no APL de coco em Touros - RN. Após secagem ao ar livre por dois meses, as cascas foram carbonizadas em forno de alvenaria tipo "rabo quente JG" e trituradas em moinho de martelo. O pó resultante foi peneirado, utilizando-se a fração inferior a 40 mesh para produção de briquetes em um delineamento inteiramente casualizado envolvendo 12 tratamentos (divididos em três grupos) e três repetições. Como aglutinantes, foram empregados amido de milho e argila. Os tratamentos foram divididos em três grupos, correspondendo cada grupo a uma proporção de argila, respectivamente 12, 15 e 18%, em relação ao peso seco total do briquete. Em cada grupo, as proporções de amido foram de 6, 8, 10 e 12%. O pó de carvão foi misturado com a argila finamente triturada e a seguir foi adicionado o amido pré-gelatinizado em água a 80°C. A massa para cada tratamento foi misturada até completa homogeneização, separando-se quantidades de 17 gramas de massa por repetição. Os briquetes foram produzidos em briquetadeira de laboratório, com pressão de 1.500 psi e tempo de prensagem de quatro minutos. Foram avaliadas as seguintes propriedades dos briquetes: densidade aparente, poder calorífico, composição química imediata (umidade, teores de carbono fixo, matérias voláteis e cinzas) e resistência à compressão. Os melhores tratamentos para fins comerciais foram os 12/12 e 12/15.The present work has the objective to produce briquettes by using fine charcoal from coconut wastes as raw material and evaluate the briquette quality. Coconut piths were collected at the city of Touros, in Rio Grande do Norte state. After a 2- month air drying, coconut pith was carbonized and hereafter ground in a hammer mill. The resulting charcoal powder was sieved and the fraction less than 40 mesh was used to produce briquettes according to an entirely randomized designed experiment involving 12 treatments and 3 replications. Starch and clay were employed as binders. The treatments were divided into 3 groups, each group corresponding to a proportion of clay, respectively 12, 15 and 18%, based on the total dry weight of the briquette. Within each group, the proportions of starch were 6, 8, 10 and 12%. The carbon powder was mixed with finely ground clay was added and then the pre-gelatinized starch in water at 80°C. The mass for each treatment was mixed until homogeneous, separating quantities of 17grams of mass for each repetition. The briquettes were produced in a laboratory press (pressure of1500psi and pressing time of 4 minutes).The briquettes were dried in an oven at 60°C until constant weight. After drying, the properties of briquettes were evaluated: bulk density, high calorific value, immediate chemical composition (moisture content, fixed carbon, volatile matter and ash) and compressive strength. Best treatments for trading products were 12/12 e 12/15

Qualidade da madeira e do carvão vegetal de quatro clones de Eucalyptus com idades entre 108 e 120 meses

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.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)

WOOD DRYERS: A SUSTAINABLE ALTERNATIVE FOR INCREASED CHARCOAL PRODUCTION

The aim of the study was to evaluate the technical and economic viability of a wood dryer in the charcoal production. Drying was carried out for 72 hours using wood from Eucalyptus sp. in two classes of diameter. The average admission temperature of combustion gases in the dryer was 100-150ºC. It was determined the mass of water withdrawn by drying and estimated the amount of wood that would be consumed during the pyrolysis to remove the same amount of water, being this wood converted into charcoal mass. In the economic analysis were determined the indicators net present value, internal rate of return and discounted payback. The dryer presented technical feasibility, reducing wood moisture by 8% and, consequently, increasing the charcoal productivity by 3.3%, and economic viability, with good financial indicators for current market conditions, including a discounted payback of 6 years. In this way, the use of a wood dryer was presented as an efficient way to take advantage of an environmental liability of pyrolysis, which contributes to the increase of sustainability in the charcoal production

POTENTIAL OF MACAUBA EPICARP (Acrocomia aculeata (Jacq.) Lodd. ex Martius) FOR BRIQUETTES PRODUCTION

Briquetting is a form to aggregate value in the biomass production chain, to re-use sustainably waste and to provide high-quality solid biofuels, as well as to enable the development of the energy market. The aim of this study was to evaluate the potential of the production of briquettes from epicarp waste of macauba fruit and verify the influence of different temperatures and compaction pressures on the chemical, physical, and mechanical characteristics of the briquettes. The epicarp was reduced to particles and, then classified, dried, and characterized for their physical and chemical properties. The briquettes were produced by using compression pressures of 62, 83, and 103 bar and temperatures of 90 and 120 °C. The effect of these factors upon the variables studied was verified through regression analysis. The increase of pressure and temperature contributed to greater mass loss of the briquettes. Apparent density and energy density increased due to temperature rise. High values of energy density were obtained, which demonstrates the potential of the macauba fruit epicarp to produce briquettes for generation of thermal energyBriquetting is a form to aggregate value in the biomass production chain, to re-use sustainably waste and to provide high-quality solid biofuels, as well as to enable the development of the energy market. The aim of this study was to evaluate the potential of the production of briquettes from epicarp waste of macauba fruit and verify the influence of different temperatures and compaction pressures on the chemical, physical, and mechanical characteristics of the briquettes. The epicarp was reduced to particles and, then classified, dried, and characterized for their physical and chemical properties. The briquettes were produced by using compression pressures of 62, 83, and 103 bar and temperatures of 90 and 120 °C. The effect of these factors upon the variables studied was verified through regression analysis. The increase of pressure and temperature contributed to greater mass loss of the briquettes. Apparent density and energy density increased due to temperature rise. High values of energy density were obtained, which demonstrates the potential of the macauba fruit epicarp to produce briquettes for generation of thermal energy

WOOD THERMAL PROFILE DURING THE PYROLYSIS PROCESS

The objective of this project was to obtain the temperature profile formed in the wood during the slow pyrolysis process. For this, small holes were opened into the wood using a drill, three thermocouples were inserted in the radial portion along the length of the wood and on the surface - center direction. Three Eucalyptus wood logs, 35 cm long, 30% moisture and 8, 9 and 12 cm diameters, were used. The final pyrolysis temperature was 400 °C. The gravimetric yield of the products was calculated after the pyrolysis process.  The formation of thermal gradients was observed in the wood throughout the process. The temperature difference between the surface and the center can reach up 200 °C, in the pyrolysis of the largest diameter wood.  Thermal heights formed in the wood at 100 °C were detected, being more evident in the central portion. The thermal variation perceived in the wood can be explained by the presence of water, which demands energy for its evaporation and changes the temperature gradients, and the heat conductivity is poor due to the wood being a porous material, mainly in the carbonized zone.These phenomena influence the heat transfer during the pyrolysis process. On the surface - to - center direction, the formation of temperature gradients generates transient thermal threshold due to the drying process. Thus, a temperature gradient was formed between the surface and the center of the wood during the pyrolysis and the total time of the process will be higher in the largest diameter wood

HYDROTHERMAL TREATMENT OF EUCALYPTUS GRANDIS WOOD

 Among the technological alternatives to improve the quality and use of eucalyptus wood is heat treatment, as the wood has some features that may limit its use, such as dimensional instability, high anisotropy, and heterogeneous coloring. This study is aimed at evaluating the effect of time of hydrothermal treatment on physical, chemical, and mechanical properties of solid wood of Eucalyptus grandis. We used three trees of E. grandis, selecting only the heartwood, and prepared test specimens with dimensions of 30cmx8cmx3cm (length, width, and thickness). The hydrothermal treatment was performed in a Parr reactor using three reaction times (5, 15, and 25min) at 140°C. Partial removal of extractives occurred, especially in the outer layer of wood. There was an increase of up to 58% of its permeability because of the partial clearing of the vessel elements. There was no degradation of the main constituents of the wood, so loss of mechanical strength was observed. The hydrothermal treatment promoted the partial removal of the hydroxyl groups and/or a structural rearrangement of the hemicelluloses and cellulose, causing a reduction of the hygroscopicity of E. grandis.