Thermochemical conversion of pulverized carbon carriers under high heating rates and elevated pressures

Abstract

Understanding the thermochemical conversion of pulverized carbon carriers is important for various industries. The effect of high-heating rates and elevated pressures can significantly influence the conversion characteristics of solids. Examples of such high heating rates and elevated pressure processes include the thermochemical conversion of alternative reducing agents (ARAs) in the blast furnace for ironmaking or the dust boilers. Two high-heating rate effects can improve coal conversion rates: i) fusing of the coal maceral inertinite and ii) particle fracture due to induced thermal stresses. Elevated pressures influence the conversion rates by affecting: I) the gas-phase species transport, ii) the intrinsic reaction rate, iii) the product yields, iv) the morphology, and v) the fragmentation behavior. Particle fragmentation and inertinite fusing are beneficial for coals’ reactivity and overall burnout. A novel injection reactor, the ARA reactor, is used to investigate the thermochemical conversion of different coals under high-heating rates and elevated pressure conditions. The maximum heating rates for the reactor are in the order of 105 to 106 K/s, while the standard pressure of the experiments is 3 bar(a). The thermochemical conversion characteristics of the different coal types under different conditions are investigated using a scanning electron microscope (SEM) and burnout ratios based on the ash tracer method. The results indicate a distinct influence of the heating rate on the conversion characteristics.