Vol 62, No 1 (2019)

The correlations of the composition, structure, and properties of coal from Ukraine, Russia, Canada, Australia, the Czech Republic, Poland, and Indonesia with its Hardgrove grindability index are investigated. It is found that the Hardgrove grindability increases with increase in total carbon content C^daf and aromatic carbon content C_ar, as well as the unsaturation δ of the structure. Correspondingly, the Hardgrove grindability decreases with increase in the volatile matter and decrease in the vitrinite reflection coefficient due to increase in the aliphatic carbon content and also with decrease in unsaturation of the coal’s organic mass. The Hardgrove grindability is calculated for unoxidized (reduced) coking coal of different types (corresponding to Ukrainian State Standard DSTU 3472:2015).

The properties of coke produced from residues obtained in the atmospheric distillation of shale tar after low-temperature (250°C) and high-temperature (350°C) thermal oxidation by air injection for different periods are considered. High-temperature thermal oxidation results in the intense formation of α fraction and considerable increase in the softening temperature. By contrast, almost no α fraction is formed in low-temperature thermal oxidation. Nevertheless, low-temperature thermal oxidation ensures more complete removal of anisotropic elements (with a score greater than three according to State Standard GOST 36132) from the microstructure of the coke. The decrease in actual coke density is also less pronounced. In this paper the next denotations are made: isooctane-soluble fraction is denoted as γ fraction, isooctane-insoluble-toluene-soluble is denoted as β fraction, toluene-insoluble-quinoline-soluble is denoted as α fraction, the fraction insoluble in quinoline, pyridine and carbon disulfide is denoted as α1 fraction.

The thermal dissolution of 1GZhR coal in model aromatic solvents and industrial polyaromatic solvents is analyzed. The following polyaromatic solvents are considered: coking tar, its anthracene fraction, and petroleum gas-oil. They are employed separately and in different combinations. The degree of conversion of the coal’s organic mass, the material balance, and the composition of the products and gases formed are determined. The efficiency of the solvents based on coal tar and its anthracene fraction is established in terms of the degree of conversion of the coal’s organic mass and the group composition of the products. The extractive products of thermal solution for the individual solvents (except for the petroleum gas-oil) and their mixtures take the form of a solid pitch-like mass (softening temperature 76–118°C). They have a high content (90–94%) of quinoline-soluble polyaromatic materials.

By chromatography and mass spectroscopy, industrial diesel fractions of tar obtained by the semicoking of Kukersite shale in a Kiviter gas generator and a Petroter-1 solid-fuel system are analyzed. The content of groups and types of compounds in the samples is compared. In the Petroter-1 fraction, the content of naphthenes (1.7%), dienes (2.6%), indenes (22.1%), ketones (7.3%), and furans (3%) is about twice that in the Kiviter fraction. In the Kiviter fraction, the content of paraffins (17.4%), olefins (19%), alkylbenzenes (23%), and naphthalenes (16.1%) is higher by a factor of about 1.3. The presence of oxygen-bearing compounds in the flue oil permits satisfactory solution of the tars and asphaltenes of the petroleum residues and decrease in their pour point. In other words, the performance of petroleum fuel-oil is significantly improved.

The system considered in the present study consists of a heating furnace and a multipass recuperative heat exchanger for air preheating. Process design ensured the coordinated operation of this system by applying a basis of a probabilistic and informational approach to the organization of industrial systems. It proves optimal to increase the thermal load on the recuperative heat exchanger and decrease the thermal load on the furnace, without changing the overall heating parameters. Exergy analysis was used to validate the proposed solution and it was shown that the total exergy loss in a system with a heating furnace and a recuperative heat exchanger decreases in for recommended operating conditions. This results in fuel economy.