Effects of heating rate and particle size on pyrolysis kinetics of Mengen lignite

Mengen lignite was pyrolyzed in a thermobalance apparatus at atmospheric pr essure. The effects of heating rare and particle size on the pyrolysis kine tics were investigated. Experiments were conducted at nonisothermal conditi ons with a hearing rate range of 10-90 K/min in the pyrolysis temperature i nterval of 298-1173 K under an argon atmosphere. Two particle size ranges w ere examined: 125 > D-P > 63 and 63 > D-P > 44 mum. Although some differenc es were obtained in TG/DTG curves of the lignite samples at different heati ng rates, almost constant relative yields of 45 and 40% of the total volati le matter were calculated from 673 to 873 K for the linear segments of the TG curves of the larger and smaller size particles, respectively. Thermogra vimetric data were analyzed by reaction rate model assuming past-order kine tics, and kinetic parameters were determined. Lower activation energies wer e calculated at higher hearing rates. Minimum activation energy was obtaine d as 22.4 kJ/mol at the heating rare value of 90 K/min with 63 > D-P > 44 m um size lignite panicles. It appears to be the lowest one when compared to those obtained from the literature.