Influence of method for determining thermal conductivity of coal combustion products on calculation accuracy

Abstract

The determination of thermal conductivity of the combustion products of coal of various compositions by a simplified method and in accordance with the molecular-kinetic theory according to the Masson – Saxena equation is considered. Calculations were made for hard coal of the Volodarsky mine of grade A, Donetsk basin of grade OS, Kuznetsk basin of grade K, Tallinn section of grade G, Kizelovsky basin of grade G, and Tulganskoye deposit of grade 1B with the content of the combustible part by weight from 70.8% to 25.1%. The temperature of the combustion products varied from 200°C to 400°C in increments of 50°C, and the excess air coefficient varied from α = 1.15 to α = 1.5 in increments of 0.05. The discrepancy between the results of the simplified calculation and the results obtained by the Masson – Saxena equation was estimated using the relative error. Analysis of the calculation results showed that the thermal conductivity coefficient calculated according to the additivity rule using volume and mass fractions of the components of the combustion products is higher than that calculated using the Masson – Saxena equation at any excess air coefficients and temperature of the combustion products. With an increase in the temperature of the combustion products, in both cases, the error in determining the thermal conductivity decreases due to an increase in the value of the thermal conductivity. The use of simplified calculation methods leads to an increase in the thermal conductivity of combustion products by an average of 7.5% – 2% for coal of various compositions, depending on the temperature of the combustion products, compared with the values calculated using the Masson – Saxena equation.