NOVELTY - Thermal treatment of biomass by drying and/or embrittling, comprises: indirect drying of biomass; obtaining the heating steam by compressing a dried steam vapor escaping from the biomass; supplying the heating steam in a heating tube of the drying apparatus and condensing; discharging the heated steam condensate (4); removing the dried steam vapor escaping from the biomass and supplying to the compressor; supplying dried biomass in another directly or indirectly acting apparatus and heating with a recycle gas (8); and using the gases debound in the thermal treatment for heating recycle gas.    USE - The method is useful for thermal treatment of biomass by drying and/or embrittling.    DETAILED DESCRIPTION - Thermal treatment of biomass by drying and/or embrittling, comprises: indirect drying of biomass with a heating steam (17) in a drying apparatus (13) with internal heater elements at temperatures up to 145 degrees C, preferably up to 120 degrees C; obtaining the heating steam by compressing a dried steam vapor escaping from the biomass at pressures up to 0.4 MPa (4 bar), preferably up to 0.1 MPa (1 bar); supplying the heating steam in a heating tube of the drying apparatus and condensing by heat transfer to the biomass; discharging the heated steam condensate (4) from the drying apparatus; removing the dried steam vapor escaping from the biomass and supplying to the compressor; supplying 80-120 degrees C hot dried biomass in another directly or indirectly acting apparatus for thermal treatment (14) and heating to a temperatures of 250-600 degrees C, preferably 280-320 degrees C with a recycle gas (8) as a fuel gas; and using the gases debound in the thermal treatment for heating the recycle gas. An INDEPENDENT CLAIM is also included for an arrangement for thermal treatment of biomass, comprising the drying apparatus with internal heating steam-traversed heating elements for indirect drying of biomass at temperatures of 145 degrees C, preferably up to 120 degrees C, to a water content of 10 mass-%, a separator for separating solids from vapor, which are fed to the drying apparatus, the compressor for compressing the vapor to heating steam with a pressure of up to 0.4 MPa (4 bar), preferably to 0.1 MPa (1 bar) to form a heating steam circulation, the drying apparatus comprising an outlet for heating steam condensate, which is obtained by heat transfer to the biomass, the 80-120 degrees C hot from dried biomass from the drying apparatus is led to the apparatus for the thermal treatment and heating to a temperature of 250-600 degrees C, preferably 280-320 degrees C, and a gas circuit, in which the gases debound in the apparatus for thermal treatment of the biomass is led to the combustion chamber and the recycle gas of the combustion chamber is led to the apparatus for thermal treatment.    DESCRIPTION OF DRAWING(S) - The figure 1 shows a schematic representation of the synthesis plant for producing methanol.    Heated steam condensate (4)    Recycle gas (8)    Drying apparatus (13)    Apparatus for thermal treatment (14)    Heating steam (17)