the present invention concerns a process and an apparatus for thermal conversion of biomass and organic wastes . according to the invention , the feedstock is fed into a fluidized - bed reactor , wherein the feed is converted at an elevated temperature under the influence of particulate matter kept in a fluidized state by a fluidizing gas , the particulate matter is transferred from the reactor to a regenerator for regeneration and then recirculated to the reactor after the regeneration , and the converted hydrocarbon products are recovered from the reactor . both the reactor and the regenerator comprise risers having an axially annular cross section and being equipped with multi - inlet cyclones for the separation of particulate matter . by means of the invention , it is possible to producer pyrolysis oil , the quality of which is higher than that of oil produced with the processes of the prior art . the incorporation of multi - inlet cyclones into the reactor configuration reduces gas velocities , reduces the physical size of the cyclone and shortens the residence time of gases in the cyclone .