CONTINUOUS ANNEALING METHOD

PURPOSE:To reduce energy consumption over the entire part of an annealing furnace and to stabilize an annealing operation by using gaseous fuel as the atmosphere in a soaking furnace of a continuous annealing device and using the heated gaseous fuel as fuel for a direct firing heating furnace. CONSTITUTION:Gaseous fuel such as coke furnace gas, converter gas, propane, city gas or the like is supplied as the gas to be used in a soaking furnace 3 of an annealing device into the furnace 3 through a gas supply pipe 11 in the stage of annealing continuously a cold rolled steel strip 8. Said gases contain more H2 and have larger reducing power and therefore the consumption of the gas is smaller than the conventional gaseous mixture consisting of 5-25% H2 and the balance N2. The gaseous fuel heated by the steel strip 8 in the furnace 3 enters a direct firing heating furnace 2 where the fuel is burned by the air 12 supplied in a combustion zone 13 to heat the strip 8 coming into the furnace from the preheating furnace. The atmosphere gas of the soaking furnace is used less than in the conventional practive and the driving power for supplying the gas is reduced.