An apparatus and method for consistently delivering solid fuel to the combustion zone of a furnace is disclosed. The method includes feeding the solid fuel into the material inlet of a rotating rotary air lock valve which may have slanted vanes and moving the fuel from the material inlet of the rotating rotary air lock valve to the material outlet of the rotating rotary air lock valve, and conveying the fuel and gas through a discharge conduit to a fuel feed receiver of a furnace burner having a combustion zone.