(82d) Sawdust Pyrolysis and CO2 Gasification of Petroleum Coke In a High Pressure Flat-Flame Burner

CO₂ gasification kinetics of petroleum coke were studied in a high pressure flat-flame burner from 1 to 15 atm and particle heating rate of 10⁵ K/s. The rapid pyrolysis of sawdust was also studied using an atmospheric flat-flame burner. The high initial particle heating rates of the pressurized flat-flame burner more closely match industrial heating rates (10⁶ K/s) than those provided by a drop tube reactor (10⁴ K/s) or a TGA. Effects of temperature, pressure, and residence time on pyrolysis yields, char composition, mass release, and char morphology using SEM images were determined. All experiments were performed using a feed rate of ~1 g/hr of 45-75 micron particles to represent single particle behavior. Very low tar yields (< 6 wt%) were observed during sawdust pyrolysis from 1150-1450 K, primarily caused by secondary tar cracking. The CPD model, which was originally developed for coal, predicts reasonably well measured sawdust pyrolysis yields (tar, char, and light gas) when combined with a tar cracking model. SEM images of sawdust char reveal that char morphology continues to change following complete pyrolysis even though mass release asymptotes. SEM images of petroleum coke char show small cracks on the char surface where volatiles likely escaped. The fractures on the char surface were likely caused by high heating rate and not pressure since the cracks were observed at all pressures tested. The mass release during pyrolysis of sawdust at high heating rates exceeds the ASTM volatiles test by ~10 wt%. First-order kinetic rate constants were determined for CO₂ gasification of petroleum coke.