Method of carrying out pyrolysis and pyrolysis apparatus

A pyrolysis apparatus comprising a pyrolysis reactor for pyrolysing solid fuel and a condenser for condensing pyrolysis gases separated from the solid fuel into pyrolysis oil, whereby the pyrolysis reactor is arranged in connection with a fluidized bed boiler for supplying heat required for the pyrolysis of the solid fuel at least partly by bed material of the fluidized bed boiler, wherein

• the pyrolysis reactor comprises a drying section for drying solid fuel supplied to the pyrolysis reactor, one or more moisture outlets provided in the drying section for removing from the drying section the moisture containing gases separated from the solid fuel in the drying section, a pyrolysis section for pyrolysing the solid fuel dried in the drying section, and one or more pyrolysis gas outlets arranged in the pyrolysis section for removing the pyrolysis gases from the pyrolysis section and for conducting pyrolysis gases separated from the solid fuel to the condenser, and that the drying section and the pyrolysis section are arranged sequentially in horizontal direction such that bed material and the dried solid fuel are passed essentially in horizontal direction from the drying section to the pyrolysis section, whereby the moisture containing gases separated from the solid fuel in the drying section and the pyrolysis gases separated in the pyrolysis section are removed separately.