NOVELTY - The method comprises crushing biomass, flooding in an aqueous solution, adding a chemical catalyst, filling in a reaction container (8), pressure treating and heating and/or temperature treating at a longer reaction phase with subsequent cooling of the aqueous solution and then separating the carbon particles from the reaction water. The process terminates in an intermittently operated reaction container held at high pressure level in which a pre-heating container (6) upstream to the reaction container is filled in pressure free manner.    USE - Method for the production of plant carbon by hydrothermal carbonization of biomass of respective type.    ADVANTAGE - The method ensures efficient and simple production of plant carbon by hydrothermal carbonization of biomass with less consumption of energy.    DETAILED DESCRIPTION - The method comprises crushing biomass, flooding in an aqueous solution, adding a chemical catalyst, filling in a reaction container (8), pressure treating and heating and/or temperature treating at a longer reaction phase with subsequent cooling of the aqueous solution and then separating the carbon particles from the reaction water. The process terminates in an intermittently operated reaction container held at high pressure level in which a pre-heating container (6) upstream to the reaction container is filled in pressure free manner and enters after flooding in closed filling valve through openings of the discharge valve in a pressure balance with the reaction container. The reaction product is transported by gravity force and auxiliary with spooled pump support in the reaction container. The reaction product is shifted after the end of the reaction in a cooling container present beneath the reaction container in which a connection between the reaction container and the flooded cooling container is produced through opening of the valve and a pressure balance is induced between the containers. The catalyst accelerating the reaction process penetrates during a pre-treatment phase before beginning the process by an aqueous solution in the mechanical crushing of the biomass and the biomass is supplied with an extensively homogeneous distribution of the catalyst in the threads into the reactor. The cooling of the reaction product is carried out in the cooling container by closed valves under high pressure and a pressure relief for the purpose of emptying the cooling container results through opening of the discharge valve after cooling. The release of the reaction product is released in a disposable container by the gravity after cooling and pressure relief. The reaction water is used for predominant part as use water for filling and only a slight part for the purpose of limitation of the concentration of the content materials of the reaction water is provided as sludge- and sales quantity of the process. The heating of the feedstock in the pre-heated container and the cooling of the reaction product in the cooling container are carried out in two phases, with a pre-heating of the use materials through heating of the feedstock through heating of the heating jacket with heat, that is from the cooling jacket (12) of the cooling container in the first cooling phase by direct hydraulic connection between the heating jacket of the pre-heating container and the cooling jacket of the cooling container, and with after-heating of the feedstock through switching the heating jacket on external heat supply and after-cooling of the basic materials with switching of the cooling jacket on external coolant supply. The rest heating is carried out predominantly or completely through the connection at the hot-cool jacket (10) of the reaction container under utilization of the heat freely becoming in the exothermic reaction phase. The additional heat consumption is not applicable chiefly or completely through external heat supply. The biomass is filled in partial quantity in the reactor and the partial quantity is subjected batch wisely in the reactor and also in corresponding part quantities from the reactor. The hot-cool-areas in the interior area of the container are arranged in nearly of the container jacket. The ring area in which the heat transmission areas are present is separated through a cylindrical sieve cover impermeable for water and permeable for biomass particles.    DESCRIPTION OF DRAWING(S) - The figure shows a flow diagram of a method for the production of plant carbon by hydrothermal carbonization of biomass.    Pre-heating container (6)    Reaction container (8)    Hot-cool-jacket (10)    Cooling jacket (12)    Spool water pump. (15)