TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The outlet is provided with a three-way valve, which is used with the second and the third lines for deriving the reaction products from the reactor, when the process of hydrothermal carbonization of the biomass is completed in the reactor. The reactor is provided with the several sensors, which determine a variety of process parameters including pressure, temperature, pH and/or filling level inside the reactor. A control device is provided through which a pre-determined pressure level is adjusted inside the reactor via the two-way valve during the hydrothermal carbonization of the biomass. At least three identical reactors are provided for the hydrothermal carbonization of the biomass, so that each of the reactors is suitable for the respective function required during the hydrothermal carbonization. The first line system is conducted via a first common heat exchanger, so that at least one of the three reactors is controlled and selectively filled with the mixed biomass (5M) of a second area via the first inlet, and the second line system, in which the pump is used, is conducted via the second common heat exchanger, so that the biomass of at least one of the three reactors found during the reaction process is controlled and selectively circulated from the outlet to the second inlet, and the third line system is conducted via at least one third heat exchanger starting from the three reactors, so that the reactor, in which the reaction process is completed, is emptied via the outlet. The first, the second and the third line systems are provided with several controllable two-way valves and three-way valves, which are connected with the program controller of a device, so that the steps of filling, circulation and emptying of the three reactors are adjustable and controllable. Preferred Method: The reacting biomass in the reactor is conducted through the heat exchanger by the pump via the second line. The exothermal energy of the reacting biomass in the reactor is removed through the heat exchanger, so that the reaction temperature in the reactor is maintained within the pre-determined variation range.