Effect of Extractive Removal on the Calorific Value of Brazilian Woods Residues

In wood processing, the production of residues is an unavoidable aspect to be considered. The use of wood residues is gaining importance due to the large amount generated and improper disposal, which can seriously harm environment. Burning of wood residues to energy generation is an increasingly usual practice. However, wood residues hold chemical substances that could be recovered before burning. These substances are the wood extractives, which may have many uses as natural dyes for fabrics, foods and cosmetics, as well as potential medicines. Thus, it is of great interest to study the effect of extractive removal on the calorific value of wood residues. In this work, the calorific value of three Brazilian wood species commonly used in sawmills （hymenaeacourbaril, jatoba; cedrelingacatenaeformis, cedroarana; tabebuiasp, ipe） and residues of urban trees pruning （caesalpiniaechinata, Brazil wood） were evaluated before and after extraction in hot water. In woods studied, the calorific value showed three patterns of behavior after removal of extractives soluble in hot water. For Brazil wood, the removal of extractives caused no significant change in calorific value. For cedroarana and jatoba, extractive removal led to a decrease in wood calorific value of 161.3 kcal.kg1 and 40. l kcal.kg^-1, respectively, which indicates that the extractives from these species have a positive energy potential. Finally, for ipe, the removal of extractives resulted in an increase in calorific value of wood （67.6 kcal.kg^-1）, which might encourage the recovery of extractives from wood residues before burning for energy generation.

Optimization of binder addition and compression load for pelletization of wheat straw using response surface methodology

Densification is required for efficiently handling and transporting biomass as feedstock for biofuel production.Binders can enhance straw pellet strength and improve the pellet performance.The present investigation aimed to optimize binders and compression load for wheat straw pelletization using a single pelleting unit.Response surface methodology was employed by using a four-factor,five-level central composite design with wood residue(%,w/w),bentonite(%,w/w),crude glycerol(%,w/w),and compression load(N)as process parameters.The pellet tensile strength,specific energy consumption of pelleting,and pellet density were the response variables.The higher heating value,ash content of the pellet product and the cost of the feedstock were also considered in optimizing binder addition.The developed model fitted the data and was adequate for binder analysis and optimization.Wheat straw pellet,with the addition of 30% wood residue,0.80% bentonite,and 3.42% crude glycerol,in addition to 4000 N of compressive load,was identified as optimal with good performance of pellet tensile strength(1.14 MPa),specific energy consumption(32.6 kJ/kg),and pellet density(1094 kg/m^(3))as well as low ash content(6.13%)and high heating value(18.64 MJ/kg).Confirmation tests indicated high accuracy of the model.