Iskanje po katalogu digitalne knjižnice

Opis: Four biomass residues–rosemary pomace, rosemary cake, grape seed and apple pomace– were torrefied at 250, 350 and 450 ◦C, and the physical, chemical and structural changes were characterized. The mass and energy yield decreased with increasing torrefaction temperature; the lowest mass (~10.4%) and energy yield (~10.6%) were observed for rosemary cake torrefied at 450 ◦C. The HHV increased the most for all feedstocks at 350 ◦C, with rosemary cake reaching a peak value of 36.4 MJ/kg at 350 ◦C. Ash content increased with temperature due to organic mass loss, while volatiles decreased and fixed carbon increased in most samples. The FTIR spectra showed the progressive loss of hydroxyl, carbonyl and C–O functionalities and the appearance of aromatic C=C bonds, indicating the formation of the biochar. TGA and DTG analyses revealed that the torrefied samples exhibited higher initial and maximum temperatures for decomposition, confirming improved thermal stability. The TGA-FTIR analyses of gas emissions during pyrolysis and combustion showed that the emissions of CO2, CH4, NOx and SO2 decreased with increasing degree of torrefaction. Overall, 350 ◦C was optimal to maximize energy density. The results show that agro-industrial residues can be effectively converted into sustainable biofuels, which offer the dual benefit of reducing waste disposal problems and providing a renewable alternative. In practice, such residues could be used for decentralized power generation in rural areas, co-combustion in existing power plants, or as feedstock for advanced bioenergy systems.
Ključne besede: torrefication, fuel, thermogravimetric analysis, biowaste, mass yield, energy yield
Objavljeno v DKUM: 04.09.2025; Ogledov: 0; Prenosov: 11
Celotno besedilo (3,34 MB)

Opis: The pyrolysis of raw and hydrothermally (HTC) pretreated pumpkin (PC) and hemp (HC) oilseed cakes was investigated for the first time using thermogravimetric, kinetic and thermodynamic analyses. The influence of the HTC pretreatment and the type of reaction liquid (whey or water) on the pyrolysis was investigated and the pyrolysis gases were analysed. The HTC pretreatment increases the biochar yield with values of up to 44 wt.% compared to raw oil cakes (∼27 wt.%). The HTC pretreatment with whey resulted in a higher energy and biochar yield and better biochar properties than the pretreatment with water. The tested oil cakes provided comparable energy yields, although HC provided higher biochar yields, while PC biochar showed higher hydrophobicity. The kinetic modelling shows that the activation energies () for the pyrolysis of the raw oil cakes varied between 93.6 and 529.9 kJ/mol for PC and between 71.3 and 669.9 kJ/mol for the HC sample. HTC pretreatment in water media increased the values, while the use of whey led to a decrease in the values. TG-FTIR analysis of the emitted gases showed that the HTC treatment affected the release of CO2 and hydrocarbons as well as the pyrolysis mechanism and reaction pathways
Ključne besede: oilseed cake, hydrochar, pyrolysis, thermogravimetric analysis, kinetic analysis, gas emissions
Objavljeno v DKUM: 25.04.2025; Ogledov: 0; Prenosov: 15
Celotno besedilo (9,44 MB)

Opis: In this work, the thermochemical properties of municipal solid waste (MSW) are studied using the torrefaction process as the main method for investigation. Torrefaction experiments were carried out using an electric laboratory furnace, at temperatures of 200, 250, and 300 °C. The residence time was set to 90 min. Proximate and ultimate analysis were performed on the torrefied MSW samples and compared with the properties of the raw MSW samples. In addition, the thermal properties of the obtained torrefied MSW samples were evaluated by thermogravimetric analysis (TGA) and derivative thermogravimetric analysis (DTG). The following could be stated: the obtained results showed that mass and energy yields (MY and EY, respectively) decrease with increasing when torrefaction temperature, while the heating values (HHV) increased under the same conditions (from 24.3 to 25.1 MJ/kg). Elemental analysis showed an increase in carbon content (C), from 45.7 ± 0.9 to 52.8 ± 1.05 wt.%, and decrease in oxygen content (O), from 45.6 ± 0.9 to 39.5 ± 0.8 wt.%, when torrefaction temperature is increased, which is consistent with the general definition of the torrefaction process. In addition, enhancement factors (EFs) and fuel ratios (FRs) were calculated, which ranged from 1.00 to 1.02 and 0.16 to 0.23, respectively. Some anomalies were observed during the thermal analysis, which are assumed to be related to the composition of the selected MSW. This study therefore shows that torrefaction pretreatment can improve the physicochemical properties of raw MSW to a level comparable to coal, and could contribute to a better understanding of the conversion of MSW into a valuable, solid biofuel.
Ključne besede: biomass, municipal solid waste, torrefication, energy yield, thermogravimetric analysis
Objavljeno v DKUM: 10.05.2024; Ogledov: 255; Prenosov: 27
Celotno besedilo (1,63 MB)
Gradivo ima več datotek! Več...

Opis: A survey of the subsolidus phase equilibria in the system Li2O-Nd2O3-Fe2O3 wasmade at subsolidus temperatures in the range 1000-1050 °C. A ternary phase was identified. The phase is centered on Li5Nd4FeO10, with a cubic lattice a =11.9494 A. The compound melts incongruently at 1105 °C. The magnetic susceptibility was measured in the temperature range 4-300 K. The compound is paramagnetic in the temperature range 150-300 K and follows the Curie-Weiss law. At about TN = 10 K, a long-range magnetic ordering is observed.
Ključne besede: lithium ferrites, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, magnetic properties, phase equilibrium
Objavljeno v DKUM: 01.06.2012; Ogledov: 2598; Prenosov: 40
Povezava na celotno besedilo