РАЗРАБОТКА БЕЗЗОЛЬНЫХ ПРОТИВОЗАДИРНЫХ ПРИСАДОК

Bapung coal in the Jaintia Hills of Meghalaya is important with respect to its quality. The unique physico-chemical composition (low ash, high volatiles, and hydrogen content) of the coal exhibits better utilisation prospects. The coal has low ash content (1.5–2.8 %) but high organic sulphur (2.44–3.64 %), which is intimately intermingled with the coal. The coal can be used in blends (10–15 %) with Gondwana coal (high ash, low sulphur) which is now practiced in the Bengal–Jharkhand region for producing metallurgical coke for steel plants. The high reactive content (vitrinite and liptinite, 83.7 %) of this coal improves the overall composition of Gondwana coal with high inert content; it is suitable for stream-raising and gasification. The low temperature carbonization (LTC) of coal yields coke—595 to 689 kg, tar —109 to 136 lt, liquor—51 to 77 lt, and gas—97.5 to 130.6 cubic-metre per tonne for coal. The quality of the coke is not good and found to be non-caking. The LTC tar can be more readily converted in one stage to petroleum oil due to its high hydrogen content (5.13–5.70 %).

The processing of coal-enrichment waste with high moisture and ash content is considered. Existing methods—filtration and thermal drying—are very complex and energy-intensive and have considerable environmental impact. An alternative is adsorption on lignite coke produced in the Krasnoyarsk region by thermal oxidation. Termokoks-KS lignite coke, which is low in ash and sulfur, resembles activated charcoal in its absorption properties. Experiments show that, when mixed with coal wastes, it produces a fuel blend characterized by lower ash content, satisfactory friability, and high energy yields. An industrial technology for such conditioning of coal wastes is described.

The most widely used standard tests for the evaluation of wear and extreme pressure properties are analysed in terms of eight tribological parameters. Wide variations in the test conditions are disclosed and the over-riding influence of thermal conditions on test severity is made clear. The relation between tests, such as the Timken, in which one of the two rubbing surfaces is static, and gear or cam and follower tests in which both specimens move, is explored. A preliminary account is given of a new test procedure evolved as a result of the study.

Air and oxy-fuel combustion behaviour of petcoke/lignite blends

Characterization and alkaline pretreatment of rice husk varieties in Uganda for potential utilization as precursors in the production of activated carbon and other value-added products

Energy conversion assessment of vacuum, slow and fast pyrolysis processes for low and high ash paper waste sludge

The tribological performance and tribochemical analysis of novel borate esters as lubricant additives in rapeseed oil

The antiwear and extreme pressure properties of some oil-water double soluble rare earth complexes part 1: their tribological behaviour in water

Excessive coal moisture leads to a lower heating value and power plant efficiency, and increased transportation costs. Therefore, coal stockpile management and moisture control are particularly important in regions with heavy precipitation. This paper and Part 2 address factors influencing moisture retention and migration in coal stockpiles. Part 1 of this paper series simulates phenomena of runoff, infiltration, and drainage in a stockpile after a rainfall event. Part 2 reports the effect of coal particle size and climate conditions on the rate and depth of moisture evaporation process within a coal stockpile. To perform this study, two coal samples were collected from the Witbank mine in South Africa. The results of the present study showed that smaller interparticulate void spaces because of the compaction or fines particles (−0.5 mm fraction) inhibited infiltration, leading to increased runoff volume. An increase stockpile slope increased the amount of runoff due to coal–water contact time reduction. The ability of heavy rainfall to destroy near-surface structures (erosion) happened more readily at stockpiles with high slopes and high fine content. The fine content significantly influenced the dewatering efficiency of drainage. Coals with higher ash contents had stronger moisture retention ability than that of other coals even though coals with low ash contents had a high fine content. This was ascribed to the contribution of the clay minerals, such as kaolinite, in the high ash coal. The results of this paper can be used for the effective management of coal stockpiles to prevent excessive moisture in stockpiles for the best possible utilisation of coal in power plants.

Thermochemical conversion (or pyrolysis) has emerged as an effective technique for the disposal of sludge generated in process industries. This paper reports physicochemical characterization and kinetic analysis of pyrolysis of sludge from a petroleum refinery and characterization of resultant char. The sludge had high volatile matter (>70 wt%) and low ash content (15 wt%). Pyrolysis of sludge was studied using a thermo-gravimetric analyzer (TGA). The TGA data was analyzed using two isoconversional models, viz. KAS and Vyazovkin AIC are used for the deduction of kinetic triplets, viz. activation energy, pre-exponential factor, and reaction mechanism. The activation energy (Ea ) of sludge pyrolysis varied in the 64.79–190.37 kJ/mol range. The pre-exponential factor varied from 1.18E + 07 to 4.29E + 12 s−1. The predominant solid-state mechanism of thermal conversion was an order-based reaction (F2/F3). The thermodynamic factors (viz. ΔH, ΔS, ΔG) of sludge pyrolysis were also determined. Relatively small values of (Ea – ΔH) ∼ 5 kJ/mol revealed high susceptibility of sludge for thermal conversion. Residual char after pyrolysis was characterized for physicochemical properties. The char properties were fixed carbon = 54.37%, calorific value = 22.48 MJ/kg, and BET surface area = 18.35 m2/g. These properties make char suitable for numerous applications.

The search for new alternatives to supply the overall energy demands of the Amazonia has been growing. Among the available renewable sources, the waste feedstock from the agroforestry chains stand out, but their proper characterization is an urgent need. This study proposes to assess the energy potential of five wastes from agroforestry crops of the Brazilian Amazonia by qualitative and quantitative approaches, highlighting the relation between biomass chemical composition and combustion behavior. The acai seed (AS), cocoa pod husk (CPH), coconut husk (CH), palm empty fruit bunch (PEFB), and maize cob (MC) were investigated. The high energy density (6.94 GJ m−3) and low ash content (1.4%) distinguished AS from the other biomasses. The PEFB showed the lowest ignition temperature (197 °C) combined with the highest ignition index (3.4 × 103% min−3) and net heating value (16.20 MJ kg−1). The superior amounts of hot-water-soluble extractives of PEFB (10.8%) and CPH (18.0%) anticipated the energy release in the main stage of combustion. Furthermore, increases in hot-water-soluble extractives reduced the ignition temperature, while lower H/C ratios increased the flammability. The H/C above 1.6, total lignin content up to 21.1%, and volatile matter/fixed carbon ratio above 4.4 facilitated the ignition of PEFB and MC biomasses.

Reuse potential of artichoke (Cynara scolimus L.) waste for the recovery of phenolic compounds and bioenergy

Investigation of oil agglomeration behaviour of Tuncbilek clean coal and separation of artificial mixture of coal–clay by oil agglomeration

The experiment was conducted from November to December of the year 2022 to extract the fibre from the Furcraea foetida leaf. Furcraea foetida plants are planted on the DRPCAU campus as ornamental plants and were selected for the present study. Furcraea foetida is a perennial subshrub plant that grows 4-6 feet tall and has the potential to extract natural, eco-friendly cellulosic fibres from its leaves. Furcraea foetida fibres were extracted by using the retting method in three different conditions: control (W), urea (U1), and urea (U2). It was observed that the U1 completed their retting in 10 days, and also, it became more yielding. U1 finished its retting in 12 days, while the control retting took longer. Fibre yield was higher in U2. This indicates that the use of urea significantly enhances the retting process and improves fibre yield compared to traditional methods. The results suggested that optimising retting conditions with urea could lead to more efficient production of Furcraea foetida fibres for various applications. The fibre analysis revealed high cellulose, moderate lignin, and low ash content, with moisture levels progressively decreasing across samples. These compositional traits indicate strong structural integrity and reduced impurities. When retting was optimized, efficiency improved significantly, leading to higher output and better quality fibre. This underscores the importance of selecting appropriate retting techniques, as method choice directly influences productivity and material performance. Overall, the findings highlight how fibre composition and processing strategies together determine effectiveness and yield in production.

Combining biomass, a clean and renewable energy source, with waste plastic, which serves as a good auxiliary fuel, can produce high-quality clean fuel. The performance of biomass-derived fuel can be improved by torrefaction. This study optimized the co-torrefaction of fungus bran and polypropylene (PP) waste plastic to obtain clean solid biofuel with high calorific value and low ash content (AC) using response surface methodology. Two sets of mixed biochars were investigated using a multiobjective optimization method: mass yield-higher heating value-ash content (MY-HHV-AC) and energy yield-ash content (EY-AC). PP increased the heat value, decreased AC, and acted as a binder. The optimal operating conditions regarding reaction temperature, reaction time, and PP blending ratio were 230.68 °C, 30 min, and 20%, respectively, for the MY-HHV-AC set and 220 °C, 30 min, 20%, respectively, for the EY-AC set. The MY-HHV-AC set had properties close to those of peat and lignite. Furthermore, compared with that of the pure biochar, the AC of the two sets decreased by 15.71% and 14.88%, respectively, indicating that the prepared mixed biochars served as ideal biofuels. Finally, a circular economy framework for biobriquette fuel was proposed and prospects for preparing pellets provided.