The gasification process includes providing a gasification reactor for gasifying a finely divided combustible material under pressure to form a crude gas with cinder and ash components, a quenching pipe positioned concentrically above the gasification reactor, a convection-heated boiler concentrically surrounding the quenching pipe and a gas flow guide device above the quenching pipe, the gas flow guide device being rotationally symmetric with respect to a longitudinal axis of the quenching pipe; conducting the crude gas with the cinder and ash components from the gasification reactor into the quenching pipe; feeding a quenching gas into the quenching pipe during the gasifying to form a mixed flow including the crude gas, the cinder and ash components and the quenching gas; guiding the mixed flow about a 180 degrees turn with the gas flow guide device above the quenching pipe; conducting the mixed flow into the convection-heated boiler; feeding the mixed flow from the convection-heated boiler with the help of a gas outlet device; and adjusting a gas flow speed of the mixed flow so that the cinder and ash components travelling in the mixed flow experience a cooling in the convection-heated boiler so that they loose adherence ability and are conducted through the gas outlet device from the convection-heated boiler.