A device for converting a fuel including solid components, known as a solid fuel, into a gaseous fuel, includes a pyrolysis zone (2) for pyrolyzing solid fuel, having pyrolysis elements that are capable of decomposing the solid fuel into a pyrolysis gas and into a solid pyrolysis residue, known as coke, and a combustion zone (3), which is distinct from the pyrolysis zone (2), for burning the pyrolysis gas and having combustion elements (31, 32, 33). The device also includes elements for circulating pyrolysis gas from the pyrolysis zone (2) to the combustion zone (3), which is surrounded by the pyrolysis zone (2).