Method and apparatus for carrying out reactions in a reactor with a slot-shaped reaction spaces

When carrying out reactions between at least two fluid reactants using a reactor in which the wall elements (1), slot-shaped reaction spaces (3) and cavities (5) for conducting a fluid heat-carrier located. To adapt to different processes and flow rates a modular design is chosen wherein an arbitrary number of wall elements (1) to a cuboid block (24) can be assembled, wherein DOLLAR A a) the slot-shaped reaction spaces (3) between the side surfaces (2) of are each formed of two substantially equally large and substantially parallelepipedal wall elements (1), wherein the wall elements (1) are interchangeable in the block (24) are arranged within a virtual right parallelepiped, DOLLAR a b) the reactants on the same side of the block (24) lying edge regions of the slot-shaped reaction spaces (3) is introduced and passed as the reaction mixture in the same directions in parallel flows through the reaction spaces (3) and wherein DOLLAR A c) the fluid heat carrier passing through the (inside of the wall elements 1) cavities (5) is passed.