Lab scale reactor system consists of a cylindrical retort, which is heated electrically by two separated PID-controllers. The fuel is put in a cylindrical holder of 100 mm height and 95 mm in inner diameter. Both parts are made of fibre-reinforced silica carbide (SiC) -ceramics to avoid reactions of CO, NO and ash with the wall and to avoid oxygen entering the reaction zone. The mounting and vessel for the fuel bed are mounted on a plate, which is placed on a mass balance. Air or an O2/N2 mixture is introduced through a porous plate at the bottom of the fuel bed. The combustion air supply is performed under the fuel bed through the plate. A liquid sealing filled with thermo oil is used to separate the mass balance and the reactor mechanically.