NOVELTY - Device for drying and torrefying at least a carbon-containing material flow in a hearth furnace, comprises: a drying zone (2) exhibiting an outlet (14) to remove a steam-containing drying gas flow, and an inlet (15) to recirculate at least a portion of the gas flow; a heat exchanger (4) connected with the outlet and the inlet of the drying zone to heat the gas flow; a torrefying zone (3) for degassing the dried material flow; and a burner connected with an outlet of the torrefying zone and the heat exchanger, where the heat exchanger is connected with an inlet of the torrefying zone.    USE - The device is useful for drying and torrefying at least a carbon-containing material flow in a hearth furnace.    ADVANTAGE - The device allows efficient drying and torrefying of the carbon-containing material flow.    DETAILED DESCRIPTION - Device for drying and torrefying at least a carbon-containing material flow in a hearth furnace, comprises: a drying zone (2), which exhibits an outlet (14) for removing a steam-containing drying gas flow, and an inlet (15) for recirculating at least a portion of the drying gas flow; a heat exchanger (4) connected with the outlet and the inlet of the drying zone, for heating the drying gas flow; a torrefying zone (3) for degassing the material flow dried in the drying zone; and a burner, which is connected with an outlet of the torrefying zone and the heat exchanger, and the heat exchanger is connected with an inlet of the torrefying zone, where a torrefying gas flow discharged via the outlet of the torrefying zone is burnt, heated, and used in the heat exchanger for heating the drying gas flow, and recirculated in the torrefying zone, where the drying zone and the torrefying zone exhibit two gas circuits separated from each other. An INDEPENDENT CLAIM is also included for drying and torrefying the carbon-containing material flow in the hearth furnace, comprising drying a biomass in the drying zone by the drying gas flow, and then torrefying in torrefying zone; discharging a portion of the steam-containing drying gas flow from the drying zone, heating in the heat exchanger, and then at least partially recirculating into the drying zone; discharging a portion of the torrefying gas flow resulting in the torrefying zone, and providing the burner for combustion, where the resulting exhaust gas is used to heat the drying gas flow in the heat exchanger, and recirculated into the torrefying zone, where the drying zone and the torrefying zone are operated with the two gas circuits.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic block diagram of the device.    Drying zone (2)    Torrefying zone (3)    Heat exchanger (4)    Outlet of drying zone (14)    Inlet of drying zone (15)