Analysing the effect of thermal modification on the calorific values of Eucalyptus nitens wood

Gross and net calorific value of 13 samples of Eucalyptus nitens wood were determined at HAWK (Hochschule für Angewandte Wissenschaft und Kunst), Göttingen, Germany. Among 13 samples, 12 were thermally modified and one was unmodified. Calorific values of samples were determined by using a bomb calorimeter, and the wood components (cellulose, hemicellulose, lignin, and extractives) already analysed by Wentzel et al. (2019). After determination of the values, samples were statistically analysed by R studio to find the relations among the calorific value, temperature, and wood components. The gross calorific value and net calorific value of the untreated sample of Eucalyptus nitens were found to be 18.83 MJ/kg and 17.48 MJ/kg, and after thermal modification these increased up to 20.24 MJ/kg and 18.84 MJ/kg. Upon statistical analysis, the results for lignin showed a strong correlation with the temperature of thermal treatment and calorific value.

Variability of Normative Properties of Wood Chips and Implications to Quality Control

The research was conducted with the goal to determine the variability of the quality parameters of the wood chips produced from the most favorable raw material (energy roundwood), and in the most controllable operational conditions (pellet factory), as the first step in identifying opportunities to optimize the wood chips’ quality monitoring. Four raw material types were tested: fir/spruce and beech debarked energy roundwood, as well as energy wood with bark of the same species. Sampling was conducted during six consecutive months along with laboratory testing, all according to the HRN EN ISO standards for solid biofuels. Interpretation of the results was done in relation to deviation from the first sampling results (as an indicator of the possibility to retain the quality of wood chips), and repeatability and reproducibility set in the standards (as an indicator of acceptable variability). The influence of the species and debarking process on the wood chips’ quality was analyzed as well. Relative deviation from the first sampling as well as the quality class change pointed moisture content as a normative property with the lowest possibility to retain initial values over the six-month period. Ash content results indicated a strong possibility to maintain the initial ash content class in the majority of the samples. In just three cases, the results of ash content were outside the reproducibility limits with first sampling as a reference. Gross calorific value results pointed only four samples outside the reproducibility limits with the first sampling results are set as a reference. Wood species influenced gross calorific value and the median value of the particle size distribution and debarking showed a significant positive effect on the moisture content reduction as well as on the ash content reduction. Presented findings are indicative for the investigated raw materials, however for the general conclusion on the subject of wood chips normative properties variation, various raw material types will have to be examined in further research.

CHANGES IN GROSS CALORIFIC VALUE OF THERMALLY TREATED SCOTS PINE (PINUS SYLVESTRIS L.) AND SESSILE OAK (QUERCUS PETRAEA L.) WOOD AND THEIR EXPLANATION USING FTIR SPECTROSCOPY

Scots pine (Pinus sylvestris L.) and Sessile oak (Quercus petraea L.) wood were thermally treated in an oven at the temperatures of 160°C, and 200°C under atmospheric pressure in the presence of air for 3 and 9 hrs. The mass loss and gross calorific value were determined. Non-treated wood samples achieved a gross calorific value of 22 193 J.g-1 for pine wood and 19 277 J.g-1 for oak wood. Whereas the calorific value of pine wood with increasing severity of treatment decreased, in the case of oak it increased. The mass loss increased with increasing treatment severity by both wood species. Mentioned differences in pine and oak wood behaviour using ATR-FTIR spectroscopy were explained. In the case of pine wood with increasing temperature and time of exposure a decrease of resin acids was observed. This may be contributed to decrease in GCV. In the case of oak wood, mainly at temperature of 200°C the degradation of hemicelluloses was observed that results in relative increasing in the lignin content with followed increase in the GCV.

Effect of drying techniques on yield, nutritional, minerals of wild banana pulp (Musa balbisiana Colla): physicochemical and morphological characterization thereof

PurposeThe study was aimed to compare the effect of three drying techniques viz., spray, freeze and hot air oven (HAO) drying on yield, nutritional parameters, minerals and physicochemical and morphological characterization of wild banana pulp (Musa balbisiana Colla).Design/methodology/approachContents of carbohydrate was estimated by Anthrone reagent, protein by Kjeldahl, fat by Soxhlet, dietary fiber and ash by Association of Official Analytical Chemists (AOAC), minerals by Atomic Absorption Spectrophotometry, gross calorific value by Bomb calorimeter, moisture by moisture analyzer, water activity by water activity meter, morphological characterization by Scanning Electron Microscopy (SEM), statistical level of significance at p < 0.05 by ANOVA, predictive modeling by simple and multiple linear regression.FindingsFreeze and HAO drying were standardized with matured (stage 2) and spray drying with ripe bananas (stage 6). Freeze drying showed highest yield (76.69 ± 0.15%), minerals viz., K (1175.67 ± 1.41), Fe (2.27 ± 0.09), Mg (120.33 ± 0.47), Mn (4.40 ± 0.28) mg/100 g, protein (7.53 ± 0.14%), lesser moisture (7.95 ± 0.01%), water activity (0.17 ± 0.02aw), hygroscopicity (6.37 ± 1.09%), well dispersed particles by SEM. HAO drying exhibited highest dietary fiber (18.95 ± 0.24%), gross calorific value 357.17 kcal/100 gm, higher solubility (47.22 ± 0.86%). Spray drying showed highest carbohydrate (85.29 ± 0.01%), lowest yield (28.26 ± 0.32%), required 30.5% adjuncts.Research limitations/implicationsEffect of three drying techniques and use of adjuncts were not uniform for ripe and matured bananas.Practical implicationsCommercial utilization of seeded wild banana.Social implicationsValue addition of wild banana in Assam, IndiaOriginality/valueFreeze drying of mature wild banana pulp (M. balbisiana) was found as best technique utilizing lesser energy.

TiO2 Photocatalysis for the Transformation of Aromatic Water Pollutants into Fuels

The growing world energy consumption, with reliance on conventional energy sources and the associated environmental pollution, are considered the most serious threats faced by mankind. Heterogeneous photocatalysis has become one of the most frequently investigated technologies, due to its dual functionality, i.e., environmental remediation and converting solar energy into chemical energy, especially molecular hydrogen. H2 burns cleanly and has the highest gravimetric gross calorific value among all fuels. However, the use of a suitable electron donor, in what so-called “photocatalytic reforming”, is required to achieve acceptable efficiency. This oxidation half-reaction can be exploited to oxidize the dissolved organic pollutants, thus, simultaneously improving the water quality. Such pollutants would replace other potentially costly electron donors, achieving the dual-functionality purpose. Since the aromatic compounds are widely spread in the environment, they are considered attractive targets to apply this technology. In this review, different aspects are highlighted, including the employing of different polymorphs of pristine titanium dioxide as photocatalysts in the photocatalytic processes, also improving the photocatalytic activity of TiO2 by loading different types of metal co-catalysts, especially platinum nanoparticles, and comparing the effect of various loading methods of such metal co-catalysts. Finally, the photocatalytic reforming of aromatic compounds employing TiO2-based semiconductors is presented.

Thermogravimetric Study of Refuse Derived Fuel Produced from Municipal Solid Waste of Kazakhstan

Efficient waste management, including proper utilization of municipal solid waste (MSW), is imperative for a sustainable future. Among several management options, pyrolysis and combustion of MSW has regained interest because of improved combustion techniques. This work aims to investigate the thermal conversion and combustion characteristics of refuse derived solid fuel (RDF) samples and its individual compounds collected from Nur-Sultan’s MSW landfills. The waste-derived solid RDF samples originally consist of textile, mixed paper, and mixed plastic. In particular, the samples, including RDF and its three constituent components, were analyzed in the temperature range of 25 to 900 °C, at three different heating rates, by thermogravimetric method. The gross calorific value for RDF derived from Nur-Sultan’s MSW was determined to be 23.4 MJ/kg. The weight loss rates of the samples, differential thermogravimetry (DTG), and kinetic analysis were compared between individual RDF components and for the mixed RDF. Combustion kinetics models were calculated using Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Friedman methods. The results revealed that first decomposition of RDF samples was observed at the range of 180–370 °C. Moreover, the activation energy for conversion of RDF was observed to be the highest among the constituent components and gradually decreased from 370 to 140 kJ/kmol.

DISTRIBUTION OF CALORIFIC VALUE BY COKE SIZE CLASS

As is known, the specificity of the layered coking process causes the development of fracturing, which determines the formation of the granulometric composition of the coke. The article presents and analyzes data on the physicochemical properties of coke of various size classes. The expediency of studying the values of the calorific value for different classes of the size of blast furnace coke has been substantiated. For this purpose, ramp coke was taken from batteries that were significantly different in size. In particular, coke oven battery I has almost twice the useful volume of coking chambers and, accordingly, the design capacity than coke oven battery II. In addition, the height of the chambers of coke oven battery I is 7000 mm, and that of coke oven battery II is 4300 mm. The above circumstances must be taken into account when evaluating the heat of combustion of various size classes of blast furnace coke. The composition of the investigated charge consisted of classic grades of coals, which are characterized by their inherent set of quality indicators. The charge for battery I was characterized by a lower burst pressure. It is shown that the value of the highest calorific value of wet quenching blast furnace coke undergoes significant changes depending on the size. Size classes less than 25 mm are characterized by maximum values of the gross calorific value, which reach 33.0 MJ/kg and more. The level of "readiness" of coke, expressed by the value of the yield of volatile substances and the actual density of the coke, significantly affects the value of the highest calorific value. Less "finished" blast furnace coke is characterized by higher values of the gross calorific value for all particle sizes. It is concluded that the value of the highest calorific value of blast furnace coke can serve as a criterion (in addition to those already available) for assessing the degree of "readiness" of blast furnace coke. Keywords: coal, coke, coke size classes, degree of readiness, heat of combustion. Corresponding author Miroshnichenko I.V., e-mail: [email protected]