In-situ gas flow separation between biochar and the heat carrier in a circulating fluidized bed reactor for biomass pyrolysis

•A novel gas flow bed separator was designed to separate biochar from heat carriers.•The separator coupled with a CFB greatly enhances the product yield of the CFB.•The separator can rapidly and continuously separate with an efficiency of up to 99%.•The separation efficiency is affected by gas velocity and particle properties.•A mechanism of the binary particles distribution in bubble holes is first proposed.