Coke and Chemistry最新文献

Blast furnace hydrogen-rich smelting effectively reduces CO₂ emissions; however, the introduction of H₂ generates H₂O within the blast furnace, which influences the gasification reaction of coke. This study investigates the gasification reaction rates of coke in CO₂/H₂O single gas and CO₂–H₂O mixed gas atmospheres, employing an analog circuit method to construct the corresponding model. The results indicate that external gas diffusion is the rate-limiting step in the coke gasification process. In a CO₂–H₂O–N₂ (40–20–40%) mixed gas environment, the coke gasification rate is lower than the sum of the rates observed in CO₂–N₂ (40–60%) and H₂O–N₂ (20–80%) atmospheres, suggesting a competitive interaction between CO₂ and H₂O in the gasification reaction of coke. Six different methods were employed to calculate the gasification reaction rates of coke in CO₂/H₂O single gases and CO₂–H₂O mixed gases, and the results reveal that method 6 most accurately elucidates their interaction. Additionally, the effect of H₂O in the CO₂–H₂O–N₂ mixture on coke gasification is more pronounced than that of CO₂. Compared to coke gasification with only H₂O, the CO₂–H₂O mixed gas promotes the conversion of amorphous carbon, reduces the consumption of aromatics, and increases the microcrystalline size.

The environmental impact of coal-fired power plants is considered. The effect of coal combustion at a thermal power plant on the local area is assessed, and a method is developed for minimizing its impact by using coal of higher quality and optimizing the combustion conditions. Aspects of coal use during the restructuring of Donetsk Basin coal mines are discussed. Types of environmental pollution associated with coal-fired plants are noted. On the basis of engineering prediction and mathematical analysis, the current situation is assessed. Up-to-date information regarding coal mining and the power of thermal power stations in the Donetsk Basin is presented. The trends of environmental indices in the region are reviewed. It is shown that the environmental conditions in coal mining regions may be improved by using coal of higher quality at power plants. Models are proposed for the extracted value of the coal, taking account of electrical generation at thermal power plants. The conclusion is that using coal of higher quality will improve the reliability of power plants and also their economic and environmental performance.

The delayed coking of heavy petroleum residues is studied with a view to greater processing of petroleum. Means of making greater use of petroleum coke are considered. The most promising approach to disposing of noncommercial tar fractions is to form composites with binder. Coking of heavy tar from West Siberian oil in the laboratory at 475–500°C results in the following material balance: 55–62% distillates and 22–28% petroleum coke. Characteristics of petroleum coke such as the ash content, total moisture content, sulfur content, and yield of volatiles are determined. The strength of composites based on petroleum coke fines and various binders (petroleum pitch, heavy tar, bitumen) is determined. The best and least expensive binder is bitumen with a softening point of 62°C. The dependence of the clinkering ability (Roga index RI) on the bitumen content in the composite with petroleum coke (in the range from 0 : 1 to 1.75 : 1) is studied. According to the results, the clinkering index meets the standard requirements (RI > 50) when the bitumen content is 20–50 wt %.

The production of needle coke from high-temperature cracking residue enriched with alkylated naphthalenes is considered, at different coking pressures. Physicochemical characteristics of the products are presented. The chemical composition of the raw materials and the coking distillate is determined by chromatography and mass spectrometry.

The quality of a Russian gas coal was analyzed, including its caking index, coke optical texture, and the coke quality parameters for the single coal. Its influence on the properties of coal blends and the resulting coke quality was also evaluated. A comparison was made between this Russian gas coal and a gas coal from Shanxi. Although their volatile matter contents, caking indices, and vitrinite reflectance values were similar, significant differences were observed in the optical texture of the coke and the coke quality parameters. The correlations between quality indices for imported coal differed from those for domestic coal. Therefore, it is necessary to distinguish between coal qualities and coal types in order to optimize blending costs and maintain coke quality.

The plastic properties of coal samples are determined in order to establish a new method of formulating coking batch. The new approach is based not only on the quantity of plastic mass formed but also on the temperature at which it begins to form and the temperatures of maximum plasticity and hardening.

Production factors influencing coke strength are considered. The influence of the fractional composition of the coal batch on the hot strength of the coke is assessed in the laboratory of coke chemistry at Severstal’s Technological Development Center. Experiments show that the hot strength of the coke declines linearly with increase in content of the <0.5 mm fraction in the coal batch. The hot strength CSR of the coke declines by 0.35% with each 1% increase in content of the <0.5 mm fraction in the coal batch.

The mixed combustion experiments of biomass with varying particle sizes and pulverized coal (PC) were conducted using a thermogravimetric analyzer. The results indicated notable differences in the impact of biomass particle sizes on mixed combustion. Particularly, straw (X) exhibited better promotion than bamboo (Y), with X₁ and D showing the most favorable mixed combustion effects. On the other hand, Y relatively enhanced the combustion of Y₂ and Y₃. Analysis of the evolution of biomass functional group structure during the combustion process revealed that aliphatic hydrocarbons and C=C bands remained more stable at the initial stages of combustion, while aromatic hydrocarbons exhibited relative stability throughout the entire combustion process. During the decomposition of aromatic and aliphatic hydrocarbons, the fluctuations in the ratios of generated –CH₃ and –CH₃ of new radicals were minimal. However, there was a general trend of gradual reduction in the length of the aliphatic branch as the combustion time increased. Micro-characterization analysis demonstrated that during the degassing process of pulverized coal, pyrolysis reactions occurred, leading to the breakdown of oxygen-containing small molecules and aliphatic rings within aromatic structures present in the coal. The addition of biomass expedited the pyrolysis of pulverized coal and facilitated the graphitization process. Subsequent addition of bituminous coal resulted in an increase in stacking height, leading to a more orderly arrangement of carbon atoms.

In the current study, reduced graphene oxide (rGO) based on coconut shell waste was successfully synthesized using the carbonization method to remove Direct Blue 86 (DB86) pollutant dye from an aqueous solution. As per our knowledge, this is the first report where coconut shell-based rGO was used to remove DB86. Several state-of-the-art analytical techniques like XRD, XPS, UV–Vis, FTIR, Raman spectroscopy, BET, and TEM were performed to thoroughly characterize as-prepared rGO. The XRD analysis shows dominant peaks at 2θ of 23.39°, 43.15° and 46.40°. FTIR spectroscopy shows compounds' functional groups. XPS C1s spectrum shows a major peak at 284.6 eV corresponding to graphitic carbon and the sp²C shows a major peak at 283.2 eV. Raman spectra show the I_D/I_G intensity ratio of 0.73. Through HRTEM analysis the interplanar distance comes out to be 0.29 nm. The obtained specific surface area of rGO was ~273 m²/g using BET analysis. These analytical outcomes confirmed the formation of rGO. Further, the synthesized rGO was assessed for its dye removal efficacy using DB86 aqueous solution. The as-prepared rGO samples showed a significant dye removal efficiency of approximately 76% after 60 min of incubation, which might be due to the chemical interactions with dye molecules. The result of post-adsorption characterization study demonstrates that rGO almost retained its chemical properties, indicating its stability after adsorption. Subsequently, rGO can be successfully synthesized on a large scale using this renewable natural waste material (i.e., coconut shell waste) by carbonization method which could be used for wastewater treatment.

The reaction of coal with gases complicates its extraction and processing. In particular, nitrogen and carbon dioxide are used to localize and extinguish underground fires and warehouse fires. On heating coal aggregations, different gases may have very different effects on coal’s organic mass. Thermogravimetric analysis reveals individual stages in the decomposition of coal and permits prediction of its behavior in the presence of gases. In the present work, the reactivity of coal’s organic mass on pyrolysis in inert gas (nitrogen), oxidizing gas (oxygen), and redox gas (CO₂) is assessed. The coal samples employed are of limited and moderate metamorphic development; they are susceptible to oxidation and self-ignition in coal beds, in storage, and in transportation. Thermogravimetric analysis indicates that, if oxygen is present, it will be adsorbed, with increase in the sample mass in the range 150–350°C. On that basis, the risk of coal oxidation and self-ignition may be assessed. In the presence of nitrogen and carbon dioxide but not oxygen, reducing reactions predominate, with the formation of solid carbon residue. In contrast to pyrolysis in inert gas (nitrogen), pyrolysis in carbon dioxide is accompanied by gasification, with increase in the coal’s mass loss at low and moderate temperatures.