Devolatilization of large coal particles at high pressure

Devolatilization times of large (0.1 and 0.2 g) Utah hvBb and North Dakota lignite coal particles, in the range 15-30s, were measured in air at 101 and 507kPa, at air temperatures of 900 and 1200K in a convective flow reactor. Visual observations indicated infrequent heterogeneous ignition of the lignite prior to devolatilization and occasional explosion of bituminous coal particles during devolatilization. Devolatilization times were correlated with temperature, pressure and particle size. Power-law exponents for tests at 101kPa and 900K were determined to be 2.5 for Utah hvBb coal and 2.2 for North Dakota lignite. At 507kPa and 900K, exponents decreased to 1.6 for both Utah and North Dakota coals. At 101kPa and 1200K, exponents were 1.9 for Utah coal and 1.6 for North Dakota lignite. Copyright (C) 1996 Elsevier Science Ltd.