Method for reducing the volume of atmosphere needed to inhibit ingress of ambient oxygen into the furnace chamber of a continuous heat treatment furnace

摘要

The volume of atmosphere needed to inhibit the ingress of ambient oxygen into the furnace chamber (3) of a continuous heat treatment furnace (1) can be reduced by introducing a gas containing free oxygen (e.g. air) into the entrance section (2) and/or exit section (4) adjacent the roof thereof. Thus a relatively inexpensive gas may often be used in combination with an expensive atmosphere thereby significantly reducing overall process cost. Continuous heat treatment furnaces can readily be converted to perform the method by simply inserting adjacent the roof of the entrance and/or exit section a tube (3) having a slot and/or a plurality of downwardly facing holes (9) and connecting the tube to a supply of the requisite gas. The invention is applicable to both double open ended furnaces and continuous furnaces in which the exit section is filled with a liquid, e.g. oil or molten salt. In these latter cases the gas is introduced in the entrance section (2).