Soot removal from furnaces used for fully automatic gas carburising - where limited amt. of air is fed into furnace for slow oxidn. of soot deposited on furnace walls

摘要

Less than the stoichiometric amt. of air required to burn the soot is fed into the furnace while the latter is at 600-900 degrees, esp. 750-850 degrees C, the amt. of air being controlled by measuring a component, esp. O2, in the furnace atmos. During the supply of air, the furnace temp. is increased by max. 200 degrees C., and pref. by ca. 50 degrees C.; and the deposited layer of soot is burnt away. The soot removal process is stopped as soon as an excess of air is present in the furnace atmos. The O2 in the furnace atmos. is pref. measured via a ZrO2-oxygen sensor; and the supply of carburising gas is only stopped after the furnace temp. has fallen to the temp. selected for soot removal, i.e. between 750-850 degrees C. The process of soot removal, is accurately controlled by the ZrO2 sensor.