A method for converting a heavy hydrocarbon feedstock into a lighter hydrocarbon stream and coke by thermal conversion and coke conversion by combustion in a redox chemical loop wherein:
- a thermal conversion of the heavy hydrocarbon feedstock is carried out in a thermal conversion zone by bringing it into contact with hot inert particles to produce, in the absence of dioxygen and a catalyst, optionally in the presence of water vapour and/or dihydrogen, a first gaseous effluent of hydrocarbon compounds and coke, the latter being deposited on the inert particles,
- the coked inert particles are discharged from the thermal conversion zone and are sent to a reduction zone of a redox chemical loop in which particles of an oxygen-carrying solid flow,
- a combustion of the coke deposited on the discharged coked inert particles is carried out in the reduction zone to produce a second gaseous effluent, hot inert particles at least partially freed from coke and oxygen-carrying solid particles in the reduced or partially reduced state, the oxygen-carrying solid particles in the reduced or partially reduced state forming a bed located above a bed formed by the inert particles in the reduction zone,
- the oxygen-carrying solid particles in the reduced or partially reduced state are discharged from the reduction zone and at least partially returned to an oxidation zone of the chemical loop to oxidise them by means of an oxidising gas before reintroducing them into the reduction zone,
- the hot inert particles which are at least partially freed from coke are discharged from the reduction zone and at least partially returned to the thermal conversion zone, the energy necessary for the thermal conversion reaction being at least partially provided by the exothermic combustion of all or part of the coke in the reduction zone.