Coke and Chemistry最新文献

The advantage of coke dry quenching (CDQ) over the conventional wet quenching process in coke making not only helps in reducing the coke moisture (<1%) but also helps in power generation, by utilizing the sensible heat of incoming hot coke in the CDQ chamber. In addition to these benefits, other advantages are – Prevention of dust emission during coke quenching, Improvement in the performance of Blast Furnace, and Improved coke quality. In the CDQ process, the coke yield can be improved by reducing the solution loss reaction within the CDQ chamber. To achieve the same, a plant trial has been taken at the CDQ unit of Tata Steel Jamshedpur, with higher CO and H₂% in the recirculating gas composition. The trial results found that it significantly affects coke quality and enhances the coke yield by 0.3% due to a reduction in solution loss reaction in the CDQ chamber. In the current article, methodology used to reduce the solution loss reaction and its positive impact on coke quality and coke yield is discussed.

In coke shop 1 at Ural Steel, double ten-roller screens are employed for primary sorting of coke to isolate the >25 mm fraction, which is sent by conveyers to large-coke hoppers for subsequent loading on railroad cars. These screens are of complex design and difficult to maintain and repair, while the drives are of low efficiency. In screen operation, unplanned downtime is encountered. To improve their reliability, the existing drives of the sorting stands and the mechanisms for moving the screen are replaced by simpler and more reliable designs with a gear motor. Updating the screens simplifies their design and improves their reliability; reduces maintenance and repair costs and the frequency of unplanned downtime; and lowers production costs.

In this work, a ternary acidic deep eutectic solvent (DES) comprising zirconyl chloride, choline chloride, and malonic acid was employed to modify coal fly ash, followed by chlorosulfonic acid sulfonation to prepare a coal fly ash-derived solid acid catalyst (CFA–DES–A). The catalyst exhibited outstanding performance in the condensation of ethylene glycol with cyclohexanone, affording a 92.4% yield under mild conditions (95°C, 4 h), with negligible loss of activity after five consecutive cycles. Structural characterizations revealed that the synergistic interplay between the acidic medium and the high dissolution capacity of the DES was crucial for generating a structurally robust material with markedly enhanced surface area and a high density of strong acid sites. In contrast, modification with either an acidic aqueous solution alone or a neutral binary DES (ZrOCl₂–ethylene glycol) failed to achieve comparable improvements.

Attention focuses on the composition of the organic component in coal tar from Shubarkol Komir and its fractions boiling below 150°C and at 170–190 and 220–250°C. Out of the total number of phenols, gas–liquid chromatography identifies only 11 compounds in the coal tar (24.97% of the total tar mass). The presence of 26.15% paraffins (C₁₀–C₃₃) is also established. In the <150°C fraction, the phenol content is 51.53%, and the content of paraffins (C₁₀–C₂₅) is 11.41%. The 170–190°C fraction contains 16.29% phenols and 15.40% paraffins (C₁₀–C₂₆). Finally, the 220–250°C fraction contains 1.47% phenols and 31.45% paraffins (C₁₀–C₂₉). These results confirm that such coal tar may be regarded as a practical source of valuable aromatic hydrocarbons.

The chemical composition and properties of coal ash from the Kaa-Khem (GZh), Mezhegey (Zh), and Elegest (Zh) fields in the Ulug-Khem Basin are compared in order to develop recommendations for the use of such coal. Elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and X-ray fluorescent spectroscopy are used to study the organic and mineral components of the coal and to determine the main ash components (SiO₂, Al₂O₃, Fe₂O₃, CaO, etc.). In accordance with State Standard GOST 11022–95, the ash content of the coal is determined at 815 ± 10°C. The fusibility characteristics (softening point and melting point), the slag viscosity, and the slagging and fouling are calculated. It is found that the ash from the Kaa-Khem coal (39% SiO₂, 14% Al₂O₃, 21% Fe₂O₃, and 12% CaO) is very thermostable (t_so = 1154.6°C). The ash from the Mezhegey coal (10% SiO₂, 8% Al₂O₃, 36% Fe₂O₃, and 24% CaO) is of elevated basicity (I_b = 3.83), with a low melting point (1105.2°C). The ash from the Elegest coal (32% SiO₂, 19% Al₂O₃, 23% Fe₂O₃, and 14% CaO) has a balanced composition, with moderate slag viscosity. Thus, the samples with high melting point (Kaa-Khem and Elegest coal) have little risk of slagging, whereas the Mezhegey coal requires additional measures to decrease the fouling (R_f = 3.28). The results confirm that Tuvinian coal is promising for practical use, if the specifics of the ash are taken into account.

The briquetting of coal batch by stiff extrusion for use in the coke industry is considered, in response to the ongoing deterioration and instability of the available coal resources. Research results confirm that this is an effective method of producing strong batch components for coking. The influence of the binder on the briquet properties—mechanical strength, thermal stability, and water resistance—is studied. The optimal fractional composition for briquetting is determined. A hybrid binder is found to ensure high thermal stability and water resistance of briquets consisting of coal and coke breeze.

By scanning electron microscopy and energy-dispersive X-ray (EDX) analysis, spent catalyst (spent carbon additive) from Veba Combi Cracking of heavy petroleum residues is investigated. Analysis of the distribution of chemical elements shows that, in suspended cracking, V and Ni are deposited in macro- and mesopores and at the surface of coal particles as a result of breakdown of porphyrin complexes. The correlation between the V and N contents at concentration points suggests that disintegration of porphyrin complexes occurs first, with the formation of Ni particles, which then act as a catalyst in the decomposition of vanadyl porphyrins, which are more thermostable. The ultrafine Ni and V particles formed at the surface react with sulfur-bearing components (for example, hydrogen sulfide or sulfonic acids released in cracking), with the formation of sulfides and sulfates. Thus, the removal of metals from the cracking products is accompanied by their desulfurization on account of the formation of ultrafine Ni and V particles binding sulfur at the surface of the carbon additive. The Ca and Fe present in the carbon additive also participate in desulfurization of the cracking products and are converted to sulfides and sulfates.

The gas kinetic, physical, petrographic, and sorptional properties of coal are studied for the example of bituminous Zh coal. Special equipment is used for laboratory experiments on the saturation of coal samples by methane (sorption). By controlled gas releases (desorption) from samples of natural and artificially saturated coal, gas kinetic curves are plotted characterizing the gas depletion over time.

The collective influence of sorbed iron, manganese, sulfate, and nitrate ions—markers of water pollution from coal mines—on the physicochemical properties of the surface of AS and MS sorbents is studied by infrared (IR) spectroscopy, scanning electron microscopy, thermal analysis, and nitrogen porosimetry. The IR spectroscopic data for the relative content of oxygen groups at the sorbent surface after adsorption from the mixture correlate with the thermogravimetric results (thermal expansion coefficient, mass loss of the sample in different temperature ranges) and with nitrogen porosimetry. Changes in the proportions of Si–OH and Si–O bonds indicate restructuring of the hydrate groups and layer by layer sorption of marker ions. As a result, qualitative and quantitative changes in the proportions of pores are observed, as confirmed by porosimetry and the analysis of surface images from a scanning electron microscope.

A method is developed for automated identification of groups of macerals (vitrinite, inertinite, liptinite, and semivitrinite) and mineral inclusions from digital microphotographs of polished coal briquet surfaces. It is based on convolutional neural networks (CNN) and computer vision. For a test sample, the accuracy attained is 92.31%; that is comparable with the results of manual assessment. This method greatly increases the speed of coal assessment and reduces the subjectivity. The algorithm only works for preexisting images. The current study doesn’t address the creation of new images: the equipment required, sample preparation, and the specifics of microphotography.