Patent ID: 9518306
Filing Date: 2016-12-13
CPC Classification: C21B,F23D

Claim Text:
1. A top-firing hot blast stove, comprising: a checker chamber including a blast pipe for receiving supply of hot blast air; and a combustion chamber including a hot-blast pipe and a burner system for supplying hot blast to a blast furnace, the combustion chamber being positioned above the checker chamber, wherein the checker chamber is heated by combustion of mixed gas including fuel gas and combustion air supplied from the burner system to the combustion chamber, and hot blast which is generated while the hot blast air passing through the checker chamber is supplied to the blast furnace through the hot-blast pipe, wherein the burner system includes (i) a burner provided with a fuel gas pipe, a first combustion air pipe, and a second combustion air pipe, wherein the fuel gas pipe and the second combustion air pipe are concentrically positioned around the first combustion air pipe, and the fuel gas pipe, the first combustion air pipe and the second combustion air pipe extend up to and form a burner exit of the burner, and a wall of an outermost pipe of the concentrically positioned pipes transitions to the burner exit and a burner duct, and (ii) the burner duct communicating with the burner exit of the burner, the burner duct communicating with the combustion chamber through a burner duct outlet disposed at an opposing end of the burner duct relative to the burner exit, wherein the burner duct defines an inner diameter D wherein the burner duct includes an aperture narrowed portion mounted to and extending from an inner surface of the burner duct immediately adjacent to the burner exit formed by the fuel gas pipe, the first combustion air pipe and the second combustion air pipe, the aperture narrowed portion defining an inner diameter D