Coal char oxidation kinetics in air medium

Abstract

Study of oxidation kinetics for three types of coal char with different carbon content in air is presented. The coal char powders of anthracite, bituminous T-grade coal and 2B-grade lignite with particle size less than 80 [mu]m were tested. The coal char oxidation was researched by isothermal method via simultaneous TG-DSC analyzer Netzsch STA 449 Jupiter F3 in the temperature range of 1000-1200 °C. Measurements were carried out at ambient pressure. Volumetric flow rate of oxidizing medium into analyser chamber was 250 ml/min. Flow consisted of air and argon with volumetric ratio 24/1. Carbon average rate of oxidation reaction at each temperature were defined based on experimental results. Kinetic constants (the frequency factor and activation energy) were defined for Arrhenius equation modified with three submodels: volumetric model, shrinking core model and random pore model. The activation energy values for anthracite are 1,6-1,7 times higher than for chars of bituminous coal and lignite.