To investigate the release and transformation of fuel potassium during biomass gasification, paulownia wood is used in a fixed-bed reactor system during 500âˆ’900 Â°C. Chemical fractionation analysis are performed to study the existing form of fuel potassium. The influences of particle size and gasification temperature are discussed. The results show that release ratio of potassium increases with the gasification temperature. When the temperature is higher than 700 Â°C, the content of water-soluble and NH4Ac-soluble K decreases, and part of other occurrence modes of K turn into the insoluble K gradually. The release ratio of potassium with three different particle sizes reaches 26.65%, 32.53% and 40.56% respectively at 900 Â°C. Increase of particle size inhibits the potassium release and induces the formation of NH4Ac-soluble K. For centimeter-sized samples, potassium content at central is higher than that of surface at 700 Â°C, which is related to the formation of NH4Ac-soluble potassium. The content of potassium at different positions decreases significantly above 700 Â°C.
Keywords potassium release, transformation, biomass gasification