TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Method: The temperature of the torrefaction reaction is controlled using means for cooling and optionally also means for heating. The temperature of the biomass during the torrefaction reaction is kept within less than or equal to 50 degrees C, preferably less than or equal to 5 degrees C. The residence time of the dried and heated biomass in the torrefaction reaction is controlled separately from the residence time in a heating step preceding the torrefaction reaction. Preferred Components: The means for cooling and heating are interchangeable. The means for heating and/or cooling is represented by heat exchangers. The torrefaction arrangement further comprises at least one heating zone that comprises means for heating, where the torrefaction arrangement comprises material transport arrangements such as that the residence time of the material in the torrefaction zones can be controlled separately from the residence time in the heating zone(s). The torrefaction zone comprises a helicoid screw or a flight conveyor. The helicoid screw is a helicoid screw flight or a helicoid screw flighting welded on a central pipe or a helicoidal screw feeder. The torrefaction arrangement comprises a first compartment in which the heating zone(s) is/are arranged and a second compartment in which the torrefaction zone(s) is/are arranged, where at least one of the compartments is a rotatable drum. The first compartment is a first rotatable drum connected to a first device for controlling the rotational speed of the first rotatable drum. The second compartment is a second rotatable drum connected to a second device for controlling the rotational speed of the second rotatable drum independent of the rotational speed of the first rotatable drum so that the residence time in the heating zone(s) can be controlled separately of the residence time in the torrefaction zone(s). In the arrangement, a screw is fixed in the rotatable drum so that the material in the drum is transported when the drum rotates. EXAMPLE - No suitable example given.