Coal burners, rotary furnaces incorporating the same and methods of operating

A rotary metal melting furnace comprising a generally cylindrical furnace rotatable about a horizontal axis, a charging opening at one end of said furnace on said horizontal axis, means for rotating said furnace about its axis, a burner opening at the other end of said furnace on said axis, burner means in said burner opening, said burner means including a generally cylindrical burner housing coaxial with the furnace housing, a fuel inlet tube spaced inwardly from and coaxial of the burner housing and forming a combustion air passage there-between said fuel inlet tube having spaced discharge and inlet ends, a refractory heat resistant imperforate generally conical diverter member on the discharge end of said inlet tube in the path of fuel in said fuel inlet tube forming a generally conical discharge pattern in the fuel leaving the fuel inlet tube around the exterior of said diverter member, a generally helical flight between the outer periphery of the inlet tube and the interior of the burner housing beginning at a point intermediate the ends of said inlet tube and within the combustion air passage surrounding the fuel inlet tube and terminating adjacent the diverter, means delivering pre-heated air to the combustion air passage spaced from the helical flight opposite the diverter member, means normally delivering pulverized coal in fluid suspension to said inlet tube adjacent the inlet end, means removably insertable into the inlet end of said fuel inlet tube for delivering a stream of fluid hydrocarbon fuel for furnace start-up and preheating when a cover is removed, recuperator means communicating with the exhaust opening of said furnace and coal pulverizing means adjacent the burner opening and fluidizing means receiving said pulverized coal and suspending said pulverized coal and delivering the same to said fuel inlet tube.