PROBLEMS OF BIOMASS ASH UTILIZATION FROM BOILER HOUSES IN UKRAINE

As result of the study, it was estimated that in 2019 in Ukraine the annual biomass ash formation to be utilized, amounted to 132 thousand tons, and in the future, subject to the goals of bioenergy development, it may increase almost 10 times until 2050. The main way to treat biomass ash in Ukraine is to bury it in landfills, partly use in landfills as an insulating material, and partly as fertilizer, mainly in homesteads. In Ukraine, the widespread use of biomass ash is limited by the lack of legal requirements for its utilization, absence of technical requirements for its use in the construction industry, complex procedure of state registration of pesticides and agrochemicals, which puts biomass ash in unequal competitition with the mineral fertilizers. Also, a certain barrier to the use of biomass ash as a fertilizer is its physical and chemical characteristics, which require special methods of its application. The increase in useful utilization of ash requires field research of its effectiveness as a fertilizer, development of different types of fertilizers based on biomass ash for different types of soils and crops and methods of their use with proven efficiency, development of the most efficient utilization methods of the ash, which does not meet the requirements of its use in agriculture, in other industries.

U–Pb Zircon Geochronological and Petrologic Constraints on the Post-Collisional Variscan Volcanism of the Tiddas-Souk Es-Sebt des Aït Ikko Basin (Western Meseta, Morocco)

The NE–SW trending Tiddas Souk Es-Sebt des Ait Ikko (TSESDAI) basin, located at 110 km southeast of Rabat, in the region of Khmesset between the village of Tiddas Souk Es-Sebt des Ait Ikko, is the third largest late Palaeozoic continental trough in the northern Central Moroccan Meseta. It is a ~20 km long and ~2–3 km wide basin, comprising mainly mixed volcano-sedimentary reddish-purple continental Permian rocks laying with an angular unconformity on Visean deep marine siliciclastic sediments and unconformably overlain by the Triassic and Cenozoic formations. In this study we aim to better determine the age of Permian volcanics and their chemical and mineralogical characteristics, as well as assess the provenance of inherited zircons, thus contributing to the understanding of the late stages of the Variscan orogeny in Morocco. The standard volcanic succession includes the following terms: (i) andesites, lapilli tuffs and andesitic ash deposits; (ii) accumulations of rhyolitic lavas; (iii) lapilli tuffs and rhyolitic ash (formation F1); (iv) flows and breccias of dacites; (v) andesite flows; and (vi) basaltic flows. The various volcanic and subvolcanic studied rocks display calc-alkaline-series characteristics with high contents of SiO2, Al2O3, CaO, MgO, and relatively abundant alkalis, and low contents of MnO. In the classification diagram, the studied facies occupy the fields of andesites, trachy-basalts, dacites, trachydacites, and rhyolites and display a sub-alkaline behavior. These lavas would be derived from a parental mafic magma (basalts) produced by partial fusion of the upper mantle. Specific chemical analyses that were carried out on the mineralogical phases (biotite and pyroxene) revealed that the examined biotites can be classified as magnesian and share similarities with the calc-alkaline association-field, while the clinopyroxenes are mainly augites and plot on the calc-alkaline orogenic basalt field. Andesites and dacites of TSESDAI show similarities with the rocks of the calc-alkaline series not linked to active subduction and which involve a continental crust in their genesis. The existence of enclaves in the lavas of the TSESDAI massif; the abnormally high contents of Rb, Ba, Th, and La; and the systematic anomalies in TiO2 and P2O5 indicate also a crustal contamination mechanism. Three magmatic episodes are distinguished with two episodes that correspond to an eruptive cycle of calc-alkaline andesites and rhyolites followed by a basaltic episode. The SHRIMP U–Pb geochronologic data of zircons recovered from the rhyolite dome of Ari El Mahsar in TSESDAI basin show a Concordia age of 286.4 ± 4.7 Ma interpreted to date the magmatic crystallization of this dome. Thus, the rhyolite likely belongs to the third magmatic episodes of TSESDAI.

Evaluation of the Bioenergy Potential of Temer Musa: An Invasive Tree from the African Desert

Temer musa (Prosopis chilensis) is an invasive wild tree found in the desert of many countries, e.g., Eritrea, Ethiopia, Sudan, India, South Africa, and the USA. The thermochemical properties of this invasive tree were analyzed as a potential biomass feedstock for energy generation. The calorific value measurement of the temer musa wood was found to be 19.83 MJ/kg. Thermogravimetric analysis and derivative weight profiles displayed that the decomposition happened in four stages representing moisture content, volatile matter, fixed carbon, and ash formation. The proximate parameters are in good range with other known biomasses and are found suitable for the thermochemical energy conversion. The gasification process confirmed the existence of several gases that are usually observed in invasive biomasses. All gasification gases were in the acceptable range, and no hydrogen sulfide gas was observed, which makes the conversion as environment friendly. The obtained results show that the energy conversion of temer musa is suitable for real-time implementation.

Modelling Particle Size Distribution of Residual Fly Ash from Pulverized Biomass Combustion

The present work aims to develop a simple model for describing the particle size distribution (PSD) of residual fly ash from pulverized biomass combustion. The residual ash formation was modelled considering the mechanism of fragmentation and coalescence. The influences of particle shape and stochastic fragmentation on model description of the PSD of the fly ash were investigated. The results showed that biomass particle shape has a great influence on the model prediction, and a larger fragmentation number is required for cylindrical particles than that for spherical particles to get the same PSD of fly ash, and the fragment number of the particles increases with the shape factor increasing. For pulverized biomass with a wide size distribution, the model predicted ash PSD considering the stochastic fragmentation is very similar to that assuming uniform fragmentation. It implies that the simple model assuming uniform fragmentation is applicable for predicting fly ash size distribution in practical processes where biomass particles have a wide range of sizes. For the fuel with a narrower initial PSD, the stochastic fragmentation model generally predicts a coarser PSD of the residual ash than assuming uniform fragmentation. It means the stochastic fragmentation is of great influence to be considered for accurate description of ash formation from the fuel with a narrow PSD.