Alfredo Napoli

Characterization of residues from plant biomass for use in energy generation

The use of plant residues for energy purposes is already a reality, yet in order to ensure suitability and recommend a given material as being a good energy generator, it is necessary to characterize the material through chemical analysis and determine its calorific value. This research aimed to analyze different residues from plant biomass, characterizing them as potential sources for energy production. For the accomplishment of this study, the following residues were used: wood processing residue (sawdust and planer shavings); coffee bean parchment and coffee plant stem; bean stem and pod; soybean stem and pod; rice husk; corn leaf, stem, straw and cob; and sugar cane straw and bagasse. For residue characterization the following analyses were done: chemical analysis, immediate chemical analysis, calorific value and elemental analysis. All procedures were conducted at the Laboratory of Forest Biomass Energy of the Federal University of Lavras. In general, all residues showed potential for energetic use. Rice husk was found to have higher lignin content, which is an interesting attribute as far as energy production is concerned. Its high ash content, however, led to a reduction in calorific value and fixed carbon. The remaining residues were found to have similar energetic characteristics, with corn cob showing greater calorific value, followed by coffee plant stem, both also containing higher levels of carbon and fixed carbon. A high correlation was found of higher calorific value with volatile materials, carbon and hydrogen contents.

Near infrared spectroscopy for estimating Eucalyptus charcoal properties

Steel can be produced from vegetable charcoal used as a thermo reducer in steel blast furnaces. Hence, the metallurgical industry requires new solutions for controlling the quality of their charcoal in order to maintain the same quality standard. The objective of this study was to assess the properties of charcoal by near infrared spectroscopy. Partial least square (PLS) regressions were established for estimating fixed-carbon, volatile matter content and gravimetric yield of charcoal. These models were validated by cross-validations and independent test sets and presented similar performance. PLS-R models obtained from untreated NIR spectra for FCC and VMC yielded promissory statistics [r2p of ∼0.9; root mean squared error of prediction (RMSEP) of ∼3.3%; and ratio of the standard error of prediction to standard deviation (RPD)>3] while the statistics of the calibrations for gravimetric yield had relatively lower magnitude (R2p of ∼0.8, a RMSEP of ∼2.2 and RPD<2). Since new solutions are required for controlling the quality of charcoal with speed and precision, these models can be useful for monitoring charcoal quality in steel industries.

Air drying of logs from an Eucalyptus urophylla clone for carbonization use

A secagem da madeira e uma das etapas do processo de carbonizacao e seu controle e de grande importância no rendimento e na qualidade do carvao vegetal produzido. Nas empresas produtoras de carvao, apos o corte, a madeira e empilhada nas margens das estradas ou proxima aos fornos de carbonizacao e e carbonizada apos 90 dias de secagem ao ar livre, quando se deseja alcancar 30% de umidade. Neste trabalho, objetivou-se avaliar a secagem ao ar livre de toras de um clone de Eucalyptus urophylla empregado na producao de carvao vegetal, analisando-se a perda de umidade no tempo, influencia da casca e do diâmetro das toras no processo. Foram utilizadas toras com casca e sem casca, com diâmetros variando de 6,0 a 21,0 cm, densidade basica media de 0,496 g/cm3 e 3,60 m de comprimento, provenientes de um talhao comercial de Eucalyptus urophylla com 8 anos de idade. Pilhas de secagem ao ar livre foram instaladas em Paraopeba, Minas Gerais, Brasil e o acompanhamento da secagem foi realizado por pesagens periodicas das toras durante 80 dias. Ao final deste estudo, observou-se que as maiores perdas de umidade ocorreram nas tres semanas iniciais. A umidade das toras sem casca (54%) e com casca (50%) foram proximas apos 80 dias de secagem, com uma maior reducao de umidade para as toras sem casca. A influencia da casca na perda de umidade foi mais pronunciada nas tres primeiras semanas. A reducao de umidade ocorreu em intensidades diferentes em funcao do diâmetro das toras. Apos 80 dias, a maior reducao de umidade foi observada nas toras sem casca: 65% para as toras de maiores diâmetros e 80% para as de menores diâmetros. Ja, para as toras com casca os resultados foram respectivamente 56% e 75%.

Estimation of the mechanical properties of wood from Eucalyptus urophylla using near infrared spectroscopy

Mechanical properties studies of wood usually involve destructive wood assessments, with time-consuming tests that use large amounts of resource (wood). Although this is not a limiting factor, it could be attenuated by the use of a nondestructive technique known as near infrared spectroscopy (NIRS). This technique has been applied to evaluate compounds containing C-H, N-H, S-H or O-H bonds, and involves quick analyses and can be applied to process control tasks. The objective of this work is to use the NIRS technique to obtain calibrations for mechanical properties of Eucalyptus sp. wood. A natural E. urophylla hybrid at age 7 was used as obtained from V&M Florestal crops. Spectra were measured directly in solid wood (radial, tangential and transverse faces) and in ground wood, in diffuse reflectance mode, using a Bruker spectrometer in the 800 to 1,500 nm range. The NIRS technique proved suitable to estimate modulus of elasticity in solid wood, with values r=0.91 and RPD=2.6, and in ground wood, with values r=0.87 and RPD=2.0. Modulus of rupture and compressive strength presented r values below 0.9. First and second derivative pretreatments provided a slight increase in correlation values for the properties in question. Calibrations for different plank faces did not present a defined variation pattern. Solid wood and ground wood presented similar correlation values for all properties.

Babassu nut residues: potential for bioenergy use in the North and Northeast of Brazil

Babassu is considered the largest native oil resource worldwide and occurs naturally in Brazil. The purpose of this study was to evaluate the potential of babassu nut residues (epicarp, mesocarp and endocarp) for bioenergy use, especially for direct combustion and charcoal production. The material was collected in the rural area of the municipality of Sítio Novo do Tocantins, in the state of Tocantins, Brazil. Analyses were performed considering jointly the three layers that make up the babassu nut shell. The following chemical characterizations were performed: molecular (lignin, total extractives and holocellulose), elemental (C, H, N, S and O), immediate (fixed carbon, volatiles and ash), energy (higher heating value and lower heating value), physical (basic density and energy density) and thermal (thermogravimetry and differential thermal analysis), besides the morphological characterization by scanning electron microscopy. Babassu nut residues showed a high bioenergy potential, mainly due to their high energy density. The use of this biomass as a bioenergy source can be highly feasible, given their chemical and thermal characteristics, combined with a low ash content. Babassu nut shell showed a high basic density and a suitable lignin content for the sustainable production of bioenergy and charcoal, capable of replacing coke in Brazilian steel plants.

Use of near infrared spectroscopy to distinguish carbonization processes and charcoal sources

The near infrared spectroscopy (NIRS) has shown a rapid and accurate technique for evaluation of materials of biological origin. The objective of this study was to evaluate the ability of the near infrared (NIR) spectroscopy associated to the Principal Component Analysis (PCA) for the separation of carbonization processes and identification of the origin of the woods used in the carbonizations. Hence, the charcoal of seven species of Eucalyptus and twenty native species from the Cerrado (savannah) of Minas Gerais, Brazil were investigated. The Eucalyptus wood was carbonized in a laboratory furnace and in a 190 m3 industrial rectangular kilns while the wood of native vegetation was carbonized only under laboratory conditions. The samples were grinded for NIR spectra acquirement. The NIR spectra were analyzed by PCA but no cluster were identified allowing discrimination between charcoal produced from native and from Eucalyptus wood. However, the cluster formed in the PCA when using the first derivative NIR spectra permitted to distinguish charcoal produced in different processes of carbonization. Two groups of data for charcoal produced in the industrial rectangular kilns were also observed, suggesting heterogeneity in the carbonization process.

Influência da temperatura no rendimento dos produtos da carbonização de #Eucalyptus microcorys#

Durante a producao de carvao vegetal, diferentes produtos sao formados. Esses produtos sao resultantes, principalmente, da temperatura final de carbonizacao. Sendo o carvao vegetal um dos principais insumos na producao de ferro gusa no Brasil, no presente trabalho, objetivou-se avaliar a influencia da temperatura final de carbonizacao no rendimento dos produtos gerados, e tambem verificar a influencia da posicao radial e longitudinal de amostragem nos rendimentos de cada produto. Para isso, foram retiradas amostras da posicao interna e externa ao longo do raio e tambem de tres diferentes alturas a partir de quatro arvores de Eucalyptus microcorys. As amostras foram carbonizadas em forno eletrico experimental adaptado, com condensador resfriado a agua e frasco coletor de materiais volateis condensaveis. As temperaturas finais de carbonizacao foram de 500, 600, 700, 800 e 900oC. Em seguida, foram calculados os rendimentos gravimetricos em carvao, liquido pirolenhoso e gases nao condensaveis. Os resultados mostram que nao houve diferenca de rendimento gravimetrico em carvao nas posicoes longitudinais e radiais estudadas; o rendimento em liquido pirolenhoso e gases nao condensaveis apresentaram variacoes nas temperaturas de 700°C e 800°C; a variacao do rendimento gravimetrico em carvao, entre as temperaturas de 500°C a 900°C foi de 15%; a variacao do rendimento em liquido pirolenhoso no sentido radial de amostragem foi, em media, de 8%; a variacao do rendimento em gases nao condensaveis no sentido radial de amostragem foi, em media, de 16%.

Specific cutting energy consumption in a circular saw for Eucalyptus stands VM01 and MN463

Modern technologies for continuous carbonization of Eucalyptus sp. require special care in wood cutting procedures. Choosing the right tool, cutting speeds and feed rates is important to manage time and energy consumption, both of which being critical factors in optimizing production. The objective of this work is to examine the influence of machining parameters on the specific cutting energy consumption of Eucalyptus sp. stands MN 463 and VM 01, owned by V&M Florestal. Tests were performed at the Wood Machining Laboratory of the Federal University of Lavras (DCF/UFLA). Moist logs 1.70m in length were used. The experiment was set up using a 3 x 3 x 4 x 2 factorial design (cutting speed x feed rate x number of teeth x tree stand). Results were subjected to analysis of variance and means were compared by the Tukey test at the 5% significance level. Greater cutting speeds, lower feed rates and the 40 teeth circular saw consumed more specific energy. Stand MN 463 consumed more specific energy. The combination of cutting speed 46 m.s-1, feed rate 17 m.min-1 and 24 teeth circular saw produced better specific energy consumption results for stand MN 463. As for stand VM 01, the combination of cutting speed 46 m.s-1, feed rate 17 m.min-1 and 20 teeth circular saw resulted in lower specific energy consumption.

Activated carbons prepared by physical activation from different pretreatments of amazon piassava fibers

ABSTRACT This study aimed to evaluate the effect of different pretreatments of Amazon piassava (Leopoldinia piassaba) fibers on microstructure, thermal, and physical properties of the ensuing activated carbons (ACs). ACs were prepared from untreated and pretreated piassava fibers by physical activation using CO2 at 800°C. Pretreatments include: mercerization, corona discharge, and removal of extractives. Scanning electron micrographs showed the formation of nanoscale pores after the activation process of the charcoal. ACs from pretreated piassava fibers presented lower crystallinity and higher thermal stability than the untreated sample. ACs from Amazon piassava fibers are potential adsorbent materials for a myriad of applications.