Influence of K/C Ratio on Gasification Rate of Biomass Chars

摘要

The present study investigates the influence of the K/C ratio on the gasification rate during char conversion. Chars of five agricultural biomasses are investigated: kiwi branches, olive branches, grape pomace, torrefied grape pomace, and sugarcane bagasse. Chars of the biomasses were produced in N-2 in a single particle reactor at 800 degrees C and subsequently gasified in CO2 in a TGA at 800 degrees C. The sugarcane bagasse char had a high Si content and a lower reactivity, which often is attributed to the presence of noncatalytic silicates. SEMEDX analysis of the initial Si-rich char revealed that most of the K was not bound as silicates. Around 30-60% of the K was lost during the char gasification of the chars. The K/C ratio increased as the char conversion proceeded. The instantaneous char gasification rate increased until the K/C ratio was around 0.1 for four of the chars. For coal chars and pure carbons, it has been suggested that the catalytic char gasification rate is saturated when the K/C ratio is 0.1. The results of the present study imply that catalytic char gasification rate may become saturated at high degrees of conversion. From 0% to 80% of conversion, the chars showed a similar catalytic behavior: the rate increased almost linearly with the K/C ratio.