The effect of ash fusion characteristic on the structure characteristics of carbon and the migration of potassium during rice straw high-temperature gasification process

Abstract

The effect of ash fusion characteristic on the structure characteristics and gasification activity of residual carbon, and the migration of K during biomass (rice straw, BRS) gasification at 1100 °C were investigated. Results showed that the carbon and AAEMs were wrapped by molten ash, and the residual carbons in BRS gasification char were composed of pyrolytic carbon and partial-gasified carbon. The molten ash formed spherical particles adhering to the surface of gasification char, and the particle size gradually enlarged. With the progress of BRS gasification, the BET surface area and microporous surface area decreased monotonously, and the ID1/IG values increased firstly and then decreased, and the total active sites were poorer at the gasification time of 15 and 20 minutes. The gasification activity of residual carbon had no linear relationship with gasification time, and followed the order of DBRS-25> DBRS-10> DBRS-20≈DBRS-15≈DBRS-5. Furthermore, the total content of K increased obviously, and the water-soluble K, ion-exchanged K, and acid-soluble K were changed to insoluble K with the increase of gasification time.