Abstract: A leading end located in a two-stage entrained-flow bed coal gasifier has a double-walled structure including an outer cylinder and an inner cylinder, and cooling water for cooling the leading end is supplied through an interior of the inner cylinder to cool the leading end and is then returned to a base end through a space formed between the outer cylinder and the inner cylinder. The space formed between the outer cylinder and the inner cylinder has a smaller channel area than the interior of the inner cylinder, and a swirling flow along a guide formed on an outer circumferential surface of the inner cylinder and a substantially linear flow in a longitudinal direction of the outer cylinder and the inner cylinder are applied to the cooling water returned to the base end through the space formed between the outer cylinder and the inner cylinder.

Abstract: It is possible to prevent a phenomenon by which the wall temperature of an outer cylinder rises abruptly as a layer of steam covers the inner circumferential surface of the outer cylinder and therefore decreases the heat transfer coefficient thereof, thus preventing a heat damage to the outer cylinder. Also prevented is burnout of the burner resulting from insufficient cooling due to variations in cooling efficiency at a leading end of the burner. A leading end located in a two-stage entrained-flow bed coal gasifier has a double-walled structure including an outer cylinder and an inner cylinder, and cooling water for cooling the leading end is supplied through an interior of the inner cylinder to cool the leading end and is then returned to a base end through a space formed between the outer cylinder and the inner cylinder.