NOVELTY - A gasification apparatus comprises a bubbling fluidized bed (7) containing coarser fluidized material particles in the reactor and a circulating bed above the bubbling fluidized bed containing more finely divided fluidized material particles. A return line for particles returning from the separator to the reactor ends at the level of the top of the bubbling fluidized bed or above this level.    USE - For gasifying a fuel containing plastic, chlorine or a finely-divided biomass such as wood pulp (claimed).    ADVANTAGE - The novel apparatus gasifies biomass and recycled fuels forming tars and/or containing chlorine, to provide a solution to the problems of fouled and clogged gas ducts.    DETAILED DESCRIPTION - A gasification apparatus comprises a fluidized bed reactor (1), fluidized material comprising solid particles, a feed inlet (6) for generating an ascending gas flow in the reactor, a fuel feed inlet (8), a feed inlet (13, 14) for adding fluidized material to the reactor, a gas exhaust duct (10) starting from the reactor top, a separator (11) for separating solid particles from product gas removed from the reactor, and a return line (12) for returning the separated particles to the reactor. A bubbling fluidized bed (7) containing coarser fluidized material particles can be provided in the reactor and a circulating bed above the bubbling fluidized bed. The circulating bed contains more finely divided fluidized material particles. The return line for particles returning from the separator to the reactor ends at the level of the top of the bubbling fluidized bed or above this level.    An INDEPENDENT CLAIM is also included for a method of gasifying a fuel in the fluidized bed reactor.    DESCRIPTION OF DRAWING(S) - The figure shows the above gasification apparatus.    Fluidized bed reactor (1)    Lower part (2)    Upper part (4)    Feed inlet (6)    Bubbling fluidized bed (7)    Fuel feed inlet (8)    Gas exhaust duct (10)    Separator (11)    Return line (12)    Feed inlet (13, 14)    Heat exchangers (19, 20)    Sorbent (21)    Filter (23)