Vol 59, No 10 (2016)

The expediency of introducing up-to-date systems in the preparation of coal batch for coking at ChAO Makeevkoks is evident if the quality of the coal concentrates employed is assessed in terms of technical, plastometric, petrographic, and granulometric characteristics. Coking trials indicate that separating out the small coal classes prior to final crushing significantly improves the technological characteristics (M₂₅, M₁₀) and structural parameters (the Ginzburg abrasive hardness and Gryaznov structural strength) of the blastfurnace coke produced. Introducing hydrocarbon briquets in the coal batch permits the utilization of coking waste without impairing the coke strength.

The underground gasification of coal and lignite is of interest when traditional coal extraction is impossible or unprofitable and also with increasing demand for thermal and/or electric power. In the Soviet Union, at six industrial Podzemgaz stations, beginning in the 1930s, more than 15 million t of coal was processed to obtain more than 50 billion m³ of gas. The South Abinsk station operated from 1955 to 1996, while the Angren station has been operating since 1963. Research on the underground gasification of coal has been largely theoretical, without close connection to industrial practice, and the results are based on mathematical modeling and data from 50–70 years ago. Obviously, Russia’s leading position in the underground gasification of coal has been lost. Russia now lags a number of countries that are making significant investments in the process. Note that, in Russia, despite the obvious benefits of underground gasification of coal, interest in the process has waned, on account of its significant deficiencies: the possibility of gas filtration to the surface; insufficient controllability of coal-bed preparation and thermal processing; the relatively low heat of combustion of the gas produced; and considerable losses of gas and coal underground. Note also the environmental impact of the underground gasification of coal, associated with the deformation of rock, its thermal, chemical, and hydrogeological changes, increase in its temperature, and active chemical pollution of groundwater. An obstacle to the adoption of the underground gasification of coal is the lack of clear ideas regarding the preparation and use of fuel gas. Recommendations for improving the process focus on the design of the underground gas generator and the gasification of the coal bed, without addressing the technology of the underground system, whose cost accounts for ~75% of the total equipment costs. The method proposed in the present work for the preparation of fuel gas from coal challenges the notion that the gas produced in underground gasification of coal should be divided into two products: gas and the tar (hydrocarbons) that forms in the preparation of the gas for combustion. If the specified temperatures are maintained, no condensation of hydrocarbons in the equipment and gas lines is observed, and dry dust removal from the gas may be employed, without complex processing of wastewater and of explosive and toxic materials. That significantly improves the economic and environmental characteristics of the process, Analysis of the results shows that the proposed approach to purifying the fuel gas produced by underground gasification of coal and lignite reduces capital costs in construction of the system by almost half; and the costs of gas production by a factor of 1.7. The time to recoup the initial investment is shortened by 41%; the yield of thermal energy is increased by 10.5%; and annual power output is increased by 151296 MW-h.

Operational problems at coke battery 6 of Rourkela Steel Plant in India are considered. The structure of coke battery 6 of PVR type (useful capacity of the coke ovens 41.6 m³) is described; it is characterized by bottom supply of the heating gas and hybrid heating. Removing the scale buildup from the inclined section of the heating channels improves the thermal and hydraulic conditions, extends coke-battery life, and eliminates nonuniform heating of the coke cake.

The influence of hydrogenating upgrading of heavy semicoking tar from long-flame coal on its properties and composition is studied when it is used as the solvent in the thermal dissolution of bituminous gas coal (GZh coal). It was found that the concentration of oxygen-bearing compounds declines on catalytic hydrogenation of tar at 5 MPa and on combined treatment with two hydrogen donors: tetralin and the anthracene oil. After hydrogenating treatment, the heavy semicoking tar may be used as the solvent in the thermal dissolution of GZh coal so as to obtain pitch-like products.

Optimization of the heat recovery system for secondary steam generation in pulverized-fuel lignite gasification is considered in terms of designing systems with high degrees of organization. This represents one of the final stages in the algorithm for the synthesis of industrial chemical systems with an unspecified number of elements and undefined topology, when optimal gas generator parameters have already been determined and are fixed for the given problem. Organization criteria are analyzed in the process of increasing the complexity of the nonuniform system. Consistent functioning of the system components is taken into account.

Data regarding wastewater purification by means of cold plasma in the biochemical department at Nizhny Tagil Steel Works are analyzed in the light of new information regarding the chain oxidation of hydrocarbons and their products. In chain oxidation initiated by cold plasma, oxygen-bearing products that do not undergo chain reactions are formed. Therefore, the chemical oxygen demand of plasma-treated wastewater cannot be reduced below 300—400 mg O/L.