For implementing startup and priming phases of a vegetable carbon production method, an installation includes a generator of hot gases with low oxygen content, and a fan downstream which boosts the hot gases into a lower part of a reactor. The reactor includes a column of substantial height whose upper inlet, with a temperature T3 of less than 65° C., is used to continuously load and add biomass and whose lower part has a grid for support and removal of the load, an underlying injection chamber for the gases from the generator, and a mechanism for retrieving processed substances. The installation also includes, at the outlet for cold gases at temperature T3 at the top of the reactor column, a thermal post-combustion chamber for the extracted gases, a heat exchanger, a fan, a second heat exchanger, a vent and connecting pipes. Another circuit located between the reactor and the fan includes a compressor unit to supply pressurized air at ambient temperature in the production phase and to replace the hot gases from the generator by compressed air.