Abstract
Viscosity of heavy and light coal tars from the coking process of coal blends with a decreasing portion of Ukrainian coal was measured. In addition, measurement of viscosity of mixtures of coal tar was carried out. Concentration of mixture met the standards of the regulations of the washing liquids for gas space of primary cooler. The temperature dependence of the viscosity of the tar mixture was evaluated according to some empirical equations. In particular, the equations have been used considering deviations from the ideal state. The viscosity of the individual samples of heavy and light tars was not appropriately investigated. This also applies to the temperature dependence. This is common practice for coal tar viscosity measurements in Engler units. Also, there are no empirical relationships; we cannot predict the viscosity of the tar when mixed, as we do for the petroleum oil matter. Anomalous decline in viscosity with the addition of 5–20 % light tar that corresponded to the minimum activation energy of viscous flow was revealed experimentally.
Highlights
Coal tar is the second largest product of coking plant after coke
These investigations cannot be extended to prediction of the viscosity of the coal tar mixture, since such additives are foreign to the coal tar nature
The partial pressure of tar vapor of coke oven gas in the primary cooler and in the gas collecting main may be taken into account to calculate the molecular weight
Summary
Coal tar is the second largest product of coking plant after coke. The tar is unique and irreplaceable raw source of condensed aromatic compounds, oils and pitch [1]. Recovery of tar from the high temperature coking process takes place during the cooling and partial condensation of the volatile products from coke oven. The quality of the coal charge, its humidity, the gas temperature cooling regime result in the certain ratio and properties of condensed tars. Besides PGC washing, mixing process is used for lowering the viscosity of tar to improve the sedimentation of the entrained coke chamber coal and coke particles. In addition the values of viscosity of the tar and its mixtures must be taken into account when performing engineering design, process optimization, evaluation of the dimensionless parameters (Reynolds, Prandtl), mixing energy calculation, computing the parameters of pipelines, etc
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