The objective of this article was to establish a case study regarding the sustainable energy production. It was shown that the production of briquettes is effective regarding the sustainable energy production, and also creates jobs for rural communities, reduce deforestation and meet the market demands. However, for the development of national briquettes industry, researches need to be stimulated and technological innovations created, with respect to cost reduction, especially in relation to logistic costs of transportation of raw material which was identified as the object more burdens the cost of production. Keywords: Briquette production; recycling biomass; sustainable energy. Since the beginning of the industrial revolution, the technological breakthroughs have been multiplied and the general feeling of well-being has substantially improved. However, this spectacular success, perhaps unnecessarily, resulted in many environmental problems Wu,
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Eduardo Z. Azarias M. Ananias F. E-mail: ting. E-mail: ananias. This research analyzed the production and characteristics of briquettes composed of residues of Cocos nucifera and Eucalyptus pellita wood.
A completely randomized design was used, having seven treatments and five repetitions per treatment. For the production of briquettes, 0.
After pressing, the briquettes were air-dried to the equilibrium moisture of the environment and, then, analyzed for physical, chemical and energy characteristics. The data were analyzed through analysis of variance, correlations and hierarchical cluster analysis HCA. The basic density, the apparent specific mass and the burning rate were not affected by the composition and by the equilibrium moisture of the briquettes. Urban wood waste can cause environmental problems and requires effective public policies and planning in any region where its production rate is high.
It should be noted that solid wastes, when improperly deposited, can impair the quality and availability of water; contaminate the soil; cause unpleasant odors; and endanger public health Krook et al. One solid residue produced at large scale in Brazil is the shells of coconuts Cocos nucifera.
Other wastes that need attention are those resulting from the industrial processing of Brazilian forest products. It is estimated that, annually, Wastes from the processing of eucalyptus wood have high calorific value and low ash content and this can increase the energetic properties of coconut compositions.
Specifically in relation to the coconut fruits, Andrade et al. However, in both situations, heat treatment will be an additional cost to the production of briquettes Razuan et al. Solid fuels with a good thermal efficiency can be produced from this process, which is relatively simple to implement.
Within this context, this research was aimed at the production and characterization of briquettes of residues of Cocos nucifera combined with residues of Eucalyptus pellita. The residues were ground with a hammer mill and classified by passing through a 3-mm-mesh sieve. Samples were analyzed for moisture content. The hypothesis involved in these compositions is that the addition of high-calorific and low-ash wood residues increases the energy characteristics of the abundant residues in several parts of Brazil.
The briquetting compaction of agroforestry residues was carried out inside a cylindrical metal mold made of stainless steel, using a hydraulic press with a capacity of 15 t. The binder was 0. The mixture of the residues with 0. During the manufacture of each briquette, the total volume of the mold was filled with the homogenized material, and the mass of this volume of residues corresponded to the respective mass of the briquette.
After pressing, the briquettes were air-dried until they reached equilibrium moisture with the environment. The bulk densities of coconut and eucalyptus residues were determined under the equilibrium moisture conditions from which they were collected, prior to the briquetting process in accordance with the NBR standard ABNT, The basic density and apparent specific mass of the briquettes were determined following the procedures described by NBR ABNT, Based on the principle of water displacement, the volumes of the briquettes were determined by the hydrostatic method after waterproofing the material with polyethylene film and immersion in water.
The briquettes were weighed before and after being submitted to oxidation for the determination of the mass loss. During the five-minute period, the briquettes were subjected to the flame action of a torch fueled by butane gas.
The output pressure generated was sufficient to prevent the flame from going into the burner. The lower calorific value LCV was determined with the aid of Eq 1.
The data obtained was analyzed for homogeneity variance by Levene and normality by Shapiro Wilk test and analysis of variance.
The correlations were tested and, the equations fitted to the variables. The multivariate hierarchical cluster analysis HCA was applied with the intention of identifying similarity between the treatments studied. Thus, the Manhattan distance was adopted as a measure of proximity, and the method of the average link was used as a technique for grouping similar treatments.
The Manhattan metric was chosen based on the fact that it was the least affected by the presence of discrepant values in the samples Manly, The distance between clusters was calculated using the average distance between all pairs of objects of the two different clusters.
The arithmetic averages of all variables were considered, and they were standardized with mean 0 and variance 1. All analyses were performed using Minitab The bulk density values of coconut and eucalyptus residues prior to briquetting ranged from to kg m -3 , respectively. The average bulk density value of E. Considering the energy utilization of these materials, especially with regard to combustion, such values are considered low and briquetting is a viable alternative for increasing density and better energy efficiency.
Figure 1 presents the equilibrium moisture of the briquettes after being subjected to outdoor drying and stabilization with the environment. The average values of the equilibrium moisture of the briquettes varied from Despite the absolute oscillations observed between the values, only the T7 treatment was superior to the other treatments. According to Andrade et al. It may be that, in this case, the formation of hydrogen bonds H-HO has been favored, leading to greater moisture retention.
The interaction between the particles, specifically in this treatment, may have generated surfaces more prone to the observed higher moisture. The percentagens of C. Coconut fiber bundles appear in large quantities on the surface of the T7 Figure 2 B treatment briquettes, which may be giving them a more hydrophilic behavior.
For Beker et al. Note, in Figure 3 A, that the values of the basic density of the briquettes significantly differ. The percentages of C.
Due to the lower average apparent specific mass of coconut wastes, there appears to be a tendency to decrease the basic densities as the content of this waste type increases in the composition of the briquettes. In relation to the apparent specific masses of the briquettes, there were no significant differences between the treatments Figure 3 A.
However, the material morphology and densification conditions may have favored the larger mass allocation per unit volume. According to Husain et al. The increase in the apparent specific mass, resulting from the transformation of waste into briquettes, is a highly positive factor because it presents a number of advantages, among which the following stand out: generation of a fuel with regular and cleaner dimensions, standardization of moisture and density, greater ease of handling and packaging of fuel, reduction of transport and storage costs, higher concentration of heat energy, greater thermal efficiency during firing, increased possibilities of use, greater ease of commercialization, among other advantages Quirino et al.
The burning rates of the briquettes Figure 3 A , despite the variations in the compositions and the equilibrium moisture, did not differ significantly. In this research, we obtain burning rate values between 4. For all the analyzed treatments, they remained at acceptable values, suggesting that the thermal deterioration will occur in an adequate time. In general, it is noted that the increase in the density gave rise to the burning rate of the briquettes Figure 3 B.
The authors observed similar results to those obtained in this study, evaluating briquettes of bamboo wastes and charcoal fines. Probably, the results observed are related to the high volatile contents per unit volume, which favored the ignition and combustion of the briquettes.
In analysis of Table 1 , it can be observed that the briquettes had high concentrations of volatile materials. The proportions of residues of C. Values ranged from This can be advantageous when considering direct firing in boiler furnaces and grain dryers, as well as in ceramic kilns, bakeries and pizzerias. In this condition, the ash contents ranged from 1. According to Sultana et al. Values above these may indicate that the material is contaminated and constitutes a potential pollutant.
According to Trugilho et al. Andrade et al. The fixed carbon content of the fuel is a variable dependent on and inversely proportional to the volatile and ash contents. It can be reliably said that combinations with the lowest volatile and ash contents result in higher fixed carbon contents and vice versa.
Due to the physical, chemical and thermal characteristics acquired by the briquettes, the average values related to the higher calorific values and lower calorific values were shown to be technically acceptable for some bioenergetic uses.
Paula et al. Obdzinski , analyzing briquettes from potato residues, obtained values between and kcal kg Hence, the results obtained indicate high calorific power for the briquettes produced under the presented conditions, using residues of C. The percentages of residues of C. The first cluster was formed by the T1, T2, T4 and T5 treatments, the second cluster was formed by the T3 treatment and the third cluster consisted of the T7 treatment.
Cluster I, together with cluster II, were the most suitable for energy uses. It can be observed in Table 2 that the treatments belonging to cluster I showed lower moisture, higher basic densities and apparent specific masses, high heat powers and low ash content. Such factors are paramount when the purpose is energy use. Cluster III may be classified as an intermediate for bioenergetic use depending on ash content and calorific value.
Basic density, apparent specific mass and burning rate are not significantly affected by the waste mixtures briquettes. Andrade, A. Andrade, C. Changes caused by torrefaction on urban wooden waste. Scientia Forestalis, v. ASTM E Standard test method for gross calorific value of refuse-derived fuel by the bomb calorimeter. Philadelphia: ASTM, Beker, U. Briquetting of Asfin-Elbistan lignite of Tukey using different waste materials.
WHAT ARE BRIQUETTES?