CONTINUOUS ANNEALING METHOD OF STEEL STRIP

摘要

PURPOSE:To prevent decrease in thermal efficiency for heating owing to indirect heating in the stage of annealing continuously a cold rolled steel strip by indirect heating using radiant tubes by making use of the heat retained by the waste combustion gas in the radiant tubes in preheating the steel strip. CONSTITUTION:A cold rolled steel strip 1 is first passed through the inside of a preheating furnace 12 and after the strip is preheated by the high-temp. air blown from a plenum chamber 18, the strip is passed through the inside of an indirect heating furnace 2 in which a reducing atmosphere is maintained. The strip is thus subjected to bright annealing by the radiant heat from many radiant tubes. The waste combustion gas in the tubes 6 is collected in a duct 23 and is introduced into a heat exchanger 7 where the gas heats the atmosphere gas in the furnace 12. The heated gas is fed to the plenum chamber 18 of the furnace 12. The waste combustion gas of the tubes 6 cooled by the heat exchanger 7 is fed by a blower 8 into a chimney 9. The decrease in the thermal efficiency of heating by the furnace 2 is prevented by utilizing the waste heat in the furnace 12.