Evaluation of the calorific values of wastes from some tropical wood species

The paper aims to analyze and classified some exotic wood species from tropical Africa, on regard to calorific features, in order to view the ability of their biomass to be a solid, natural and renewable fuel.  The calorific values of wood wastes of eight tropical species were determined using an oxygen bomb calorimeter. The tested specimens were conditioned at a moisture content of 10%, 20%, and 50%. The influence of moisture content on calorific value and density, heat release rate and calorific efficiency were also analyzed. The biggest high calorific value and low calorific value were obtained by Guaiac and Rose species (21200-20700 kJ/kg). Acajou had the lowest values of high calorific value and low calorific value (18929 and 18456 kJ/kg, respectively). For higher wood density (Guaiac) the higher calorific density was obtained. The moisture content of specimens had negatively influenced the calorific efficiency and rate of energy release. The ash content was below 4% with highest values for Guaiac (3.6%) and the lowest for Acajou (0.5%). The results showed that the analyzed tropical wood species had a forest calorific capacity with 23-47% higher than of European beech, thus can be considered a good potential as renewable energy resources

Particularities of hollow-core briquettes obtained out of spruce and oak wooden waste

Wooden hollow-core briquettes made of wooden waste represent an important category of wood-based combustible materials used in heating chambers. This paper aims to determine some of the characteristics of these briquettes made of spruce and oak waste. The comparison to the classic types of briquettes is made in order to identify the advantages and disadvantages of such briquettes. The main characteristics of these briquettes are presented, starting from size, density, abrasion, compression and ending with the inferior and superior calorific values, calorific density and ash content. The obtained results show that there are few differences between their characteristics and those of the classic ones. These differences depend on the pressing method and equipment, in comparison to other briquettes without a hollow core. Apart from the characteristics and the nature of the material being used, the hollow-core briquettes remain renewable combustible materials increasingly used in combustion (for heating purposes or in order to cook food or for heating in rural households or as substitutes for charcoal or cogenerate in various industrial fields). Given their economical character, there is complete suitability of these briquettes for cooking and heating

Influence of the Strand Characteristics on the Properties of Oriented Strand Boards Obtained from Resinous and Broad-Leaved Fast-Growing Species

The paper aims to investigate the influence of the characteristics of the strands on the properties of oriented strand boards (OSB). To solve this objective, some global synthetic characteristics of the strands (the slenderness ratio, the characteristics of thinness, and the specific surface) of four wood species currently used in this technology (spruce and pine for softwood, and poplar and willow for hardwood) were first studied. The characteristics of the OSB obtained from each species separately were also determined, and finally the correlations analysis was made between the characteristics of the strands and those of the corresponding OSB boards. The working methodology used the European tests regarding the physical and mechanical properties of the boards, but also algorithms for forecasting and evaluating the quality of the strands and boards. The conclusions regarding the characteristics of the strands have highlighted the role of the specific surface of the strand and the characteristics of the thickness; respectively, the conclusions regarding the characteristics of the boards showed that the fast-growing species of willow and poplar lead to obtaining higher quality OSB boards. The general conclusion of the paper is that the characteristics of the strands have a significant influence on the physical–mechanical properties of the OSB board

Torrefaction of Spruce, Beech, and Oak Pellets in Order to Improve Calorific Value

Native spruce, beech, and oak pellets were treated by torrefaction. The torrefaction was performed without oxygen, in an electric oven, at temperatures of 170 °C, 190 °C, and 210 °C and treatment periods of 1, 2, and 3 h. The results showed an increase in the calorific value of the pellets by raising the parameters of the treatment regime (temperature and duration), achieving maximum values of 18.93 MJ/kg in the case of beech pellets for 3 h and 190 °C, 18.97 MJ/kg for the roughest regime with 3 h and 210 °C in the case of spruce pellets, and 18.84 MJ/kg in the case of oak pellets with 3 h and 190 °C. The torrefaction process for beech and oak must be stopped at 190 °C and 3 hours, becoming ineffective after these values of the treatment regime. The shear strength of the pellets were decreased slightly (10 to 15%) by the torrefaction treatment, but ash content slightly increased from 17.7% for spruce pellets to 29.1% for beech pellets. The results suggest that direct torrefaction of native pellets is possible without the use of nitrogen, i.e., by turning off the oxygen intake in the torrefaction oven, with good results for increasing the calorific value with 8.7% for beech pellets, 7.5% for spruce pellets, and 7.9% for oak pellets

Ecological briquettes from sunflower seed husk

The paper aims to use the waste of sun-flower hulls in order to obtain some lignocellulosic briquettes as renewable solid fuels. First, the sunflower seed husks were ground, after that they were sorted and only the fractions corresponding to the briquettes and pellets were used. After obtaining the stable briquettes there were determined the physical and caloric properties of briquettes manufactured from sunflower husks, as potential alternative biofuels. The moisture content, ash content and density of the briquettes have been determined and correlated with their calorific properties, namely the calorific value and calorific density. The experimental results have indicated that, even if the self-adhesion of sunflower seed hulls is less than that of wood sawdust, they have a better behaviour in humid environment. Good results make it possible to use these briquettes for both household heating systems and thermal power plant

Particularities of hollow-core briquettes obtained out of spruce and oak wooden waste

Wooden hollow-core briquettes made of wooden waste represent an important category of wood-based combustible materials used in heating chambers. This paper aims to determine some of the characteristics of these briquettes made of spruce and oak waste. The comparison to the classic types of briquettes is made in order to identify the advantages and disadvantages of such briquettes. The main characteristics of these briquettes are presented, starting from size, density, abrasion, compression and ending with the inferior and superior calorific values, calorific density and ash content. The obtained results show that there are few differences between their characteristics and those of the classic ones. These differences depend on the pressing method and equipment, in comparison to other briquettes without a hollow core. Apart from the characteristics and the nature of the material being used, the hollow-core briquettes remain renewable combustible materials increasingly used in combustion (for heating purposes or in order to cook food or for heating in rural households or as substitutes for charcoal or cogenerate in various industrial fields). Given their economical character, there is complete suitability of these briquettes for cooking and heating

Effects and Modeling of Sawdust Torrefaction for Beech Pellets

This study was done to determine the effects of beech sawdust torrefaction on pellets obtained in the laboratory. Torrefied beech (Fagus sylvatica L.) sawdust was used to make pellets. This species was chosen based on the existence of a market for such micro-briquettes. Rigorous comparisons between torrefied and non-torrefied pellets were conducted. It was found that treating the sawdust had both beneficial and non-beneficial effects, but the total effect is positive. Economical elements were also considered, emphasizing the use of wood biomass as fuel. Theoretical and experimental aspects are taken into consideration, the experimental results being used to validate the theoretical model. The experiments performed demonstrate that heat treatment can add value if it meets certain parameters, such as a maximum temperature of 260 °C for 5 min. Heat treatment of beech sawdust in the form of pellets or briquettes was shown to be a simple, viable, effective treatment because the heating process improves the calorific value and other relevant properties of the torrefied sawdust

Using Deciduous Branch Wood and Conifer Spindle Wood to Manufacture Panels with Transverse Structure

The increasing demand on the wood market makes it necessary to use all secondary resources, including the wood branches and spindles. The properties of deciduous branches and softwood spindles were evaluated in order to create wood panels, highlighting the transverse texture with high value added. The research analyzed the properties of the wood from deciduous (beech, maple) branches and from conifer (spruce, fir) spindles. The methodology of obtaining panels with transversal structure was also presented. The production of minor wood (branches or spindles) was 254 m3/ha/year in the case of beech (branches) and 109 m3/ha/year in the case of spruce (spindles). The proportion of compression wood for spruce had an average value of 40.6%. A similar value of tension wood for beech was obtained. The modulus of elasticity for pine spindle wood was 71.7% lower than the modulus of elasticity for bending strength in the trunk. The quality index was 36.7% lower in the case of spindles than in the case of pine trunk, and the value of the quality ratio in branch maple wood was 2.61% lower than in trunk wood. Thus, even if it is not the only efficient solution, wood in the minor portions can be used to make high value-added panels such as those that highlight the transverse structure

Ecological briquettes from sunflower seed husk

The paper aims to use the waste of sun-flower hulls in order to obtain some lignocellulosic briquettes as renewable solid fuels. First, the sunflower seed husks were ground, after that they were sorted and only the fractions corresponding to the briquettes and pellets were used. After obtaining the stable briquettes there were determined the physical and caloric properties of briquettes manufactured from sunflower husks, as potential alternative biofuels. The moisture content, ash content and density of the briquettes have been determined and correlated with their calorific properties, namely the calorific value and calorific density. The experimental results have indicated that, even if the self-adhesion of sunflower seed hulls is less than that of wood sawdust, they have a better behaviour in humid environment. Good results make it possible to use these briquettes for both household heating systems and thermal power plant

A comparative study regarding to physical and calorific properties of briquettes from vegetable biomass

The paper makes a comparison between four types of briquettes: first was wheat and rapeseed briquettes, second was wheat briquettes (batch 2018), third was wheat briquettes (batch 2017), and fourth was lucernes briquettes, from the point of view of the physical and energetic characteristics, in order to choose the best ones and their corresponding market. The main properties studied are the density and moisture of the briquettes, physical properties, and also calorific power and ash content as energetic properties. Research results show that wheat and rape briquettes have had high calorific value but low density, compared to other types of briquettes. A general conclusion rise from whole paper, respectively the vegetable biomass is a renewable material and briquettes from it remains the best option of combustible materials