A system includes a gasifier that may gasify a feedstock to produce a syngas and a syngas cooler that includes a cooling chamber having a tapered configuration. The cooling chamber includes a first section that may separate particulates from the syngas and includes a first opening and a second opening. The first opening has a smaller width than the second opening. The system also includes a second section in fluid communication with the first section that includes a plurality of tubes surrounding the first section. A first portion of the plurality of tubes is arranged parallel to a longitudinal axis of the cooling chamber and a second portion of the plurality of tubes is angled such that the second portion of the plurality of tubes forms the tapered configuration. The system further includes a passage to flow a seal gas between a shell of the radiant syngas cooler and the second section. The shell encloses the cooling chamber.