Abstract: A fluidized bed reactor includes a bottom portion, a roof portion, and side walls vertically extending between the bottom portion and the roof portion, forming a reaction chamber of the reactor. At least one side wall of the reaction chamber forms at least one vertical indentation in the reaction chamber, which indentation extends from the plane of the at least one side wall towards the reaction chamber. The indentation extending from the plane of the at least one side wall towards the reaction chamber is formed of a portion of the at least one side wall, protruding from the plane of the at least one side wall towards the reaction chamber, and the portion of the at least one side wall includes at least two substantially vertical indenting wall portions deviating from the plane of the at least one side wall at vertical lines within a distance from each other.

Abstract: A fluidized bed reactor includes a bottom portion, a roof portion and side walls vertically extending between the bottom portion and the roof portion, forming a reaction chamber of the fluidized bed reactor. A solids separator is in connection with the reaction chamber. At least one side wall of the reaction chamber forms at least one indentation in the reaction chamber, which indentation is substantially vertical and extends from the plane of the side wall towards the reaction chamber.