Vol 61, No 8 (2018)

If the ignition temperature t_ig of the unoxidized coal determined in accordance with Ukrainian State Standard DSTU 7611:2014 is used to check the rank assignment of coal concentrates supplied to the coke plant, inconsistency of the actual and declared ranks of the coal may be identified in timely fashion, the properties of the coal may be preliminarily studied, and the results may be used in adopting measures to maintain the specified rank composition and properties of the coal batch and also to stabilize the quality of the blast-furnace coke produced. Using the ignition temperature to monitor the rank composition and quality of the coal concentrates supplied to the plant offers economic benefits, by the prevention of losses due to changes in coking-batch quality, which affect the yield and quality of the coke produced.

The formation of the combustion flame in the heating channels of coke ovens is analyzed. The need for redesign of the components so as to permit recirculation of the combustion products by thermal ejection is established. That will result in elongation of the flame. In addition, the organization of forced recirculation by the supply of combustion products or inert gas to the heating channels with ascending flux is proposed. In this approach, it is possible to use water vapor, pure nitrogen, or blast-furnace gas from a steel plant or coke plant. The analysis yields the conclusion that these measures will ensure more uniform heating over the height of the cake in existing coke batteries, slow defect formation in the channel lining, and decrease atmospheric emissions.

The influence of preliminary demineralization of coal by aqueous solutions of hydrochloric and hydrofluoric acid on the texture of sorbents produced by thermolysis in the presence of potassium hydroxide is investigated (when the mass ratio of the KOH and the coal is 2.0). The results show that successive treatment of coal with 10% hydrochloric and 10% hydrofluoric acid decreases the coal’s ash content to a residual value of about 0.6%. In thermolysis, a sorbent with an ash content of 1.5% is obtained on thermolysis. In comparison with sorbent from untreated coal, the sorbent from the demineralized coal is characterized by higher specific surface and total pore volume. In the treated coal, more than 70% of the pore space consists of micropores.

To expand the range of materials from which coal pitch may be produced, the interaction of coal tar with rubber crumbs from discarded tires is investigated. Ultrasound treatment of a tar–crumb mixture and subsequent oxidation in air at 240–360°C may be used to produce an analog of coal pitch (binder) and a light fraction. The binder characteristics may be regulated in terms of the softening temperature, which is determined by the duration of oxidation.

An acoustic method is proposed for foam suppression in the slow coking of petroleum residues. In this approach, pulsed gas motion and a high-intensity acoustic field are created at the point of foam formation. That does not compromise the sterility of the final product. The theoretical principles for formation of an acoustic field whose parameters are in resonance with the acoustic characteristics of the foam are outlined. Laboratory tests of foam suppression on a cold model show that forced disintegration of foam is possible in an acoustic field of intensity up to 120 dB. Experiments on a hot model of the slow coking of petroleum residues indicate the feasibility of foam disintegration without direct contact.

For the example of 80 organic solvents, the method developed by the All-Russian Research Institute for Fire Protection (ARRIFP) and the Baker–Strehlow–Tang (BST) method for the prediction of vapor-cloud explosions (VCE) in enclosed spaces are compared, in terms of the specific safe volume of a building. A correlation is found between the results given by these methods. On introducing an energy correction (the ratio of the calorific value of the solvent to that of methane) and a correction factor of 1/4.47, the BST method (in the 2.5D configuration with low congestion) may be used to categorize production buildings in terms of explosion and fire safety.