Study on CO2 gasification characteristics of pyrolysis char from pinewood block and pellet

Gasification reaction characteristics of pinewood block char (PW char) and pinewood pellet char (PWP char) were studied by analyzing CO (a component of syngas) generating rate at different temperatures (900, 1000, 1100 °C), respectively. The results demonstrated that the char with smaller size (15 mm) showed higher reactivity index than bigger size (30 mm). Increase in temperature (900 − 1100 °C) improved reaction rate and likely compensated for the diffusion resistance for larger particle. The reaction rate of PW char could be considered a constant varying from 10 to 90% carbon conversion when temperature was less than 1000 °C, and the nucleation and growth model with two close nucleation speed stages confirmed it. The parameter with great influence on PW char and PWP char gasification was porosity, followed by pore structure. Similar porosity between PW char and PWP char resulted in similar carbon conversion time, while more smaller pores (2–13.5 nm) of PW char led to high specific surface area (SSA) then increased higher gasification reactivity. These results are useful for gasification materials selection. Specifically of interest is adjustment of gasifier and bed layer movement to better match properties of materials.