Heating furnace

摘要

A heating furnace for heating elongate materials has a cylindrical furnace body whose both ends are closed by first and second end walls. The furnace body has an exhaust port formed near the first end wall. A material to be heated is inserted into the furnace body through penetrating holes formed in the end walls. A plurality of furnace core tubes are arranged in the body at a prescribed distance from the inner peripheral surface of the body and along the axis of the body. A heating chamber is defined by the inner surfaces of the core tubes. An air-gas passage is defined between the inner peripheral surface of the furnace body and the outer peripheral surfaces of the core tubes. The air-gas passage communicates with the heating chamber through a communication passage formed in the core tube adjacent to the second end wall. Combustion gas ejected from ejection nozzles which are formed in the first end wall is supplied into the heating chamber and then discharged from the exhaust port through the communication passage and air-gas passage.