Abstract: Disclosed is a burner for the partial combustion of a solid carbonaceous fuel, and suitable for use in an reactor having a plurality of burners wherein e.g. finely divided coal is supplied to a reactor space via a central channel disposed along the longitudinal axis of the burner, and oxygen-containing gas is supplied via an annular channel surrounding said central channel and configured for said gas to intersect said coal at an acute angle, and heat from the combustion is removed from a dimensioned curvilinear hollow front of the burner by coolant flowed radially at constant momentum through said hollow front.