DIRECT FIRING VERTICAL TYPE CONTINUOUS ANNEALING FURNACE

摘要

PURPOSE:To prevent oxidation of a steel strip in a clean heating atmosphere gas furnace by providing an intermediate chamber in which the internal pressure higher than the pressure in a vertical type direct firing heating furnace for the steel strip to be plated in a galvanizing device and the above-described gas furnace is maintained to the intermediate of the two furnaces. CONSTITUTION:A steel strip 5 to be galvanized is heated in a preheating furnace, a vertical type direct firing heating furnace 2 and a clean heating atmosphere gas furnace 3 and is then galvanized. An intermediate chamber 9 having a narrow passage in which the strip 5 passes is provided between the furnace 2 and the furnace 3. The gas in the furnace 3 is fed by a blower 10 into the chamber 9 and at the same time gaseous nitrogen is forced through another pipeline 12 into said chamber. The internal pressure in said chamber is maintained always higher than the pressure in the furnace 2 and the furnace 3 on both sides. Even if the internal pressure of the furnace 2 drops sharply with a change in the combustion condition of fuel, the drop of the internal pressure of the furnace 3 is obviated by the presence of the chamber 9 and therefore the oxidation of the strip 5 by the outdoor air intruded into the furnace 3 and the succeeding unstable galvanization are obviated.