Abstract: A reaction device is provided with a first wall that defines an interior in which a stirring mechanism is located. A heat exchanger is at least partly provided on the first outer wall surface facing away from the interior and/or on the stirring mechanism, wherein the heat exchanger has a grate structure, and at least two layers are provided which have a grate structure. Thus, it is possible to transfer heat in a precise and efficient manner primarily by means of thermal radiation in endothermic processes at different temperature levels, in particular pyrolysis, gassing, and reforming processes, and thereby use the exhaust heat for other processes.