Study on rapid pyrolysis and in-situ char gasification characteristics of coal and petroleum coke

Rapid pyrolysis characteristics of three different rank coals and two petroleum cokes were investigated using a drop tube furnace. Moreover, gasification characteristics of char samples were studied in an in-situ heating stage. The results showed that H2 and CO were the main gaseous pyrolysis products of coal samples. The relative content of H2 and CO increased with increasing pyrolysis temperature. The volume fraction of H2 in syngas increased with increasing coal rank, whereas that of CO showed the contrary trend. Anthracite and petroleum cokes (Petcoke 1 and Petcoke 2) exhibited a great similarity in gas release characteristics. There was a maximum value for the specific surface area and graphitization degree of char samples with increasing pyrolysis temperature. The results of in-situ heating stage experiments indicated that the most of char particles reacted with CO2 in the shrinking particle mode at the initial stage. Char samples of petcokes and anthracite were similar in slow consumption of particle skeleton during gasification. Interestingly, petcokes demonstrated particle migration, residual agglomeration, and rapid consumption at the later reaction stage. The variation trend of the area shrinkage ratio of char samples was well verified by the TGA results.