PURPOSE: To prevent an alumina protection tube from deterioration and damage and to improve life performance of a graphite heating element by employing a CO gas atmosphere in a heat generator space.
CONSTITUTION: Carbon monoxide gas is introduced from an end 14 of a graphite heating element 1 into an inner hole. Part of the CO gas, after filling the inside of an alumina protection tube 2 via a gas flow hole 3 arranged near the other end of the heating element, flows again to the inner hole and is discharged out of the other end 15. Use of the carbon monoxide gas prevents the heating element 1 from being damaged by oxidation and the protection tube 2 is protected from deterioration and damage. Furthermore, since graphite packings 9, 10 are able to slide easily, mechanical damage such as cracks due to the changes in lengths of the heating element 1 and the protection tube 2 as a result of the temperature changes at the time of applying and stopping current to the heating element is prevented.
OKADA MICHIYA
USAMI KENICHI
MATSUMOTO TOSHIMI
