Abstract: A method of heating up to working temperature from cold, a furnace of the regenerative or recuperative type having its interior lined with refractory material, which method comprises projecting into the furnace from one or more substantially non-radiant high velocity burners a flow of hot gases, causing said gases to circulate around said interior to heat same substantially uniformly, introducing to said interior air (preferably from the normal firing system of the furnace) alternately via one and then the other of the regenerators, and controlling said burner or burners to cause it or them to pass to an excess fuel condition by which said air is consumed within the furnace, thereby pre-heating the furnace and the regenerators up to full working temperature.

Abstract: A high velocity gaseous fuel burner has a casing with an inlet end into which air is blown to an outlet end in the form of a nozzle. Within the casing but circumferentially spaced therefrom is an elongated combustion tube into the rear end of which a main burner unit projects a fuel/air mixture. The outlet end of the tube reaches to or into the nozzle and the air blown through the casing passes over the combustion tube, some air passing into the tube through apertures in its wall. A boost burner unit may be mounted through the walls of the casing and tube to project a fuel/air mixture axially towards the casing nozzle to produce further combustion beyond the tube outlet. Valves are provided for controlling the flow of fuel and air to the two burner units jointly and/or separately.