PURPOSE: To increase the amount of transfer of radiation heat in a furnace to improve a furnace efficiency and reduce fuel consumption by a method wherein a plurality of heat exchanging tubes are arranged along the inner wall of the heating furnace and bank-shaped reflecting material layers, having a triangular section, are arranged between respective tubes in parallel to the tubes.

CONSTITUTION: A heating furnace is constituted of a layer consisting of a steel plate 1-1, a temperature keeping plate 1-2, an intermediate heat insulating material 1-3 and bricks or castable 2, whose surface is coated with a reflecting material. Respective heat exchanging tubes (heating tubes) 3, equipped with sections 4 to be heated, are arranged at the inside of the castable 2. Bank- shaped reflecting material layers 5, having a triangular section respectively, are arranged between respective heat exchanging tubes 3 in parallel to the tubes on the inner surface of a furnace wall. According to this method, the amount of transfer of radiation heat in the furnace is increased to improve a furnace efficiency while a fuel consumption is reduced to achieve, energy saving. On the other hand, the size of luminous flame is reduced whereby the amount of consumption coke is reduced.