Abstract: Convection cooler for cooling a gas produced under elevated pressure in a gasification reactor. The cooler has a pressure-tight jacket provided with a removable cover. Within the jacket there is an insert arranged spaced apart therefrom. The insert has tubes joined in gastight manner to each other by way of webs. Contact heating surfaces are arranged in the insert which is supported on the pressure jacket. The insert is closed at its upper end by way of a ceiling constructed of tubes. The contact heating surfaces are joined to support tubes. The upper ends of the contact heating surfaces and the support tubes are passed through the ceiling. The support tubes, the contact heating surfaces, and the ceiling are suspended from the cover independently of the insert. Wall soot blowers are arranged fixedly superimposed at several levels in the insert.