Kinetics of pyrolysis and Computational Fluid Dynamics modeling of low metamorphic coal

This study explores the low-temperature pyrolysis kinetic of low metamorphic grade coal from Northern Shaanxi, utilizing Fourier transform infrared (FT-IR) spectroscopy to analyze the characteristics of various functional groups over a 293–1023 K temperature range. A kinetic model, correlating with the pyrolysis behaviors of these groups, was developed through thermal analysis kinetics. Computational fluid dynamics (CFD) technology simulated the furnace's flow dynamics, allowing an examination of the physical field alterations and functional group evolution during pyrolysis. Results showed that the pyrolysis kinetic functions for aromatic C–H, C=C, C–O, and •OH, along with temperature, pressure, and velocity fields, were successfully integrated into the simulation. This integration provided detailed insights into the temperature profile, pressure distribution, flow velocities, and functional group distribution in the furnace. Aliphatics, exhibiting the largest mass fraction and wide pyrolysis temperature range, and •OH radicals with the highest activation energy were concentrated in the furnace's pyrolysis zone center. C=C's distribution was influenced by aromatic C–H and aliphatics, showing a complementary pattern. The oxygen-containing groups C–O and C=O had similar pyrolysis mechanisms and uniform distribution. The functional groups' mass fractions were ranked from highest to lowest as follows: aliphatics > •OH > aromatic C–H > C–O > C=C > C=O.