| Abstrakt: |
Study on the soot behaviors in hemicellulose pyrolysis is essential for the enhancement of gasification performance and solution of PM-related problems. In this work, a one-dimensional model is adopted to calculate the heating up and pyrolysis of xylan. The primary devolatilization is calculated by bio-CPD model, while the soot formation is simulated with one-step reaction with tar as the precursor. The effect of particle distance, soot radiation, and thermophoresis force on soot behaviors are discussed in detail. A smaller particle distance leads to less soot during xylan pyrolysis, which is contrary to the trend in biomass gasification. For pyrolysis, soot formation rate dominates, which decreases when particle distance decreases. For gasification, soot consumption rate dominates, which decreases when particle distance decreases. Soot radiation during xylan pyrolysis tends to heat up the soot itself and tar since their temperature is lower than ambient temperature, which is different from combustion and gasification conditions. Thus, when soot radiation is included in the model, temperature is higher and all soot-relevant reactions are faster. At the late stage of xylan pyrolysis, diffusion makes soot move towards both xylan particle and outer boundary, while thermophoresis offers an additional driven force for soot to get close to xylan particle. When thermophoresis is included in the model, soot mass fraction decreases more slowly at the late stage. [ABSTRACT FROM AUTHOR] |
Full text from SpringerLink