Abstract: A laminar stream reactor for the production of hydrochar of a solid-fluid mixture of water and a carbon-containing component, wherein the solid-fluid mixture is treated at a temperature of 100-300° C. and a pressure of 5-70 bar, consists of tubular reactor units of largely vertical holding sections (1,3) and direction-changing diverters (2,4). The holding sections are thereby flown through slower by the solid-fluid mixture than the remaining tube distances, as they have larger diameters.