Abstract: Gasifier for combusting a carbonaceous fuel to produce a usable gas and comprising an insulated outer shell. A combustion chamber within the shell receives a fuel mixture from a fuel injection burner. The products of combustion, including hot produced gas, are passed through a constricted throat to be cooled ion a liquid bath. A dip tube which guides the hot products into the bath, is provided with a stream of coolant from a quench ring. The latter is supported on the dip tube upper end and conformed at its exposed face to minimize the effects of the hot product gas, thereby avoiding the establishment of stress points in the ring structure.