Optimised energy efficiency hydrothermal carbonization method and device

A method of continuous hydrothermal carbonization of sludge containing organic matter, said sludge having a dryness between 10 and 30%, said method involving a stage of hydrothermal reaction carried out in a reactor (4), the hydrothermal reaction stage involving the following steps:

• a step of introduction of sludge in which the sludge is introduced into the reactor (4) by a first inlet (11),
• a step of endogenous injection of steam in which steam is injected into the reactor (4) by a second inlet (15),
• a step of extraction in which at least a portion of the sludge contained in the reactor (4) is extracted continuously by a sludge outlet (16),
• further comprising a step of preheating in which the temperature of the sludge is raised prior to its introduction into the reactor (4) up to a temperature of preheating greater than 70° C.,
• wherein the second inlet (15) is distinct from the first inlet (11),
• and wherein the step of preheating includes a step of microwave injection in which microwaves are injected into the sludge prior to its introduction into the reactor (4).