Device and method for heating furnaces by means of radiant tubes

To heat a furnace chamber (16) indirectly using radiant tubes (11) to (14), heating energy is transferred through the radiant tube wall into the furnace chamber (16). During steady-state operation, the temperature in the radiant tube (11) to (14) and on its surface is higher than the furnace, depending on the specific heat output of the radiant tube (11) to (14). At a furnace temperature of 770° C. and a heat output of 50 kW/m2, the radiant tube has a temperature of 900° C. The radiant tube (11) to (14) can thus operate continuously with flameless oxidation at this output, even though the temperature in the furnace is only 100° C. However, if the radiant tube (11) to (14) has cooled to the furnace temperature of 770° C. during a break in burning, deflagration is avoided when the associated burner is ignited by initially operating said burner with a flame for a few seconds.