Coke and Chemistry最新文献

The radiant capacity of triatomic gases such as H₂O and CO₂ is investigated as a function of the density and thickness of the gas layer (the radiant path length). It is established that, when the path length is short, the radiant capacity of carbon dioxide predominates; when it is long, the radiant capacity of water vapor predominates. Assessment of the radiant heat-transfer coefficients in heating ducts, for the example of coke battery chambers at Moskoks, indicates that the heat-transfer of water vapor makes the greatest contribution. It increases with increase in content of water vapor in the combustion products of coke oven gas. Computer experiments confirm that supplying superheated steam (around 5 vol % of the air flux) to the combustion zone increases the radiant heat-transfer coefficients from 91.2 to 106.0 W/m² K. That intensifies coking, with simultaneous decrease in the generation of nitrogen oxides. (This technique is sometimes known as green steam injection.)

At 360–420°C in a metal reactor, the thermal solvolysis of polystyrene, phenol–formaldehyde resin, polycarbonate, and epoxy resin by means of the anthracene fraction from coal tar is studied. The composition of the polymers’ thermal destruction products is determined by gas chromatography. The anthracene fraction and coal tar pitch are compared as hydrogen-donor solvents in polymer processing by thermal solvolysis.

Anthracite-based Purolate standard sorbent is studied before and after sorption of iron, manganese, sulfate, and nitrite ions, by thermal analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, and nitrogen porosimetry. Correlations are established between the thermal decomposition indices, the mass loss in different temperature ranges, and the results of X-ray photoelectron spectroscopy (relative atomic concentrations in the surface layer of samples), scanning electron microscopy (analysis of microphotographs), and nitrogen porosimetry (specific surface values of the samples).

It is of great practical importance to study the composition of coal’s organic matter in order to develop new and improved technologies for processing solid fuel, with the production of liquid fractions, hydrocarbon gases, and carbon residues. In the present work, 20 Russian and Mongolian coals of six different grades, at different metamorphic stages, undergo technical, petrographic, and chemical analysis. Thermogravimetric analysis is used to study the decomposition of coal as a function of its properties and metamorphic development. Correlations between Russian and Mongolian coals are established in terms of their chemical and technological properties, thermal decomposition, and the liberation of volatile fractions.

New approaches to thermal energy generation are necessary for reasons of resource conservation and environmental protection. One option is to convert coal-fueled boilers to mixtures based on coal and biomass or to mixtures with more efficient nontraditional fuels. However, that entails expansion of experimental resources and research. In the present work, the main stages in the combustion of carbonizates, biomass, and their mixtures are analyzed and the main stages in the combustion of such mixtures with nonisothermal heating are determined, taking account of synergy between the components. Carbonizate obtained by gasification of Chernogorsky coal, birch shavings, and their mixtures are subjected to thermal analysis in an oxidative medium, with heating at 20°C/min. The basic combustion characteristics are established: the ignition temperature of the volatiles and coke residue; the temperature at which combustion ends; the maximum rate of mass loss and the corresponding temperature; and the combustion index, which permits comparison of the combustibility of different fuels. The ignition temperature is 45% higher for the carbonizates than for birch shavings; the combustion index is lower by a factor of 25. The total combustion time is greater for the mixture than for individual fuels. The most energy-efficient fuel mixture is identified. Adding biomass to carbonizates may improve not only the combustion characteristics of the carbonizates but the environmental characteristics, thanks to the low ash content and the minimal sulfur and nitrogen content in the biomass waste.

Recycling of metals and construction materials from coal mining and enrichment tailings is considered. By mechanochemical activation of leaching, it is possible not only to recover metals but also to obtain byproducts. This research provides better understanding of metal extraction in solution by new geotechnologies based on disintegration.

Modernization of coke production at Magnitogorsk Iron and Steel Works (MMK) is considered, including the construction of a new high-capacity coke battery (annual output 2.5 million t). The use of dry quenching at this coke battery improves coke quality, decreases harmful emissions, and permits power generation. The basic characteristics of the new coke battery are outlined, and its power supply system is briefly analyzed.

The processes occurring in low-temperature pyrolysis of the α fraction of coal tar pitch over the range 25–700°C are studied by electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) spectroscopy. Up to 400°C, a sequence of processes occurs: homolytic rupture of C–C and C–H bonds is followed by recombination of aromatic π radicals to form graphite-like structures. At the threshold temperature (500°C), recombination of aromatic radicals begins to predominate. Comparison of the results with literature data indicates that, in the range 400–700°C, disordered graphite-like structures are formed. Available physicochemical methods permit detailed study of such structures.