Patent ID: 9163305
Filing Date: 2015-10-20
Classification: B32B,C21D,C22C,C23C,F27B,F27D

Abstract:
1. A continuous annealing method for steel strips, comprising annealing steel strips with a vertical annealing furnace in which a heating zone for heating the steel strips while the steel strips are being transported upward and downward, a soaking zone, and a cooling zone are disposed in this order; wherein an atmosphere gas is supplied from outside of the furnace into the furnace; wherein a gas in the furnace is discharged from a steel-strip entrance in a lower portion of the heating zone; wherein a portion of the gas in the furnace is sucked and introduced into a refiner that is disposed outside of the furnace and includes a deoxidation device and a dehumidification device to decrease a dew point of the gas through removal of oxygen and water from the gas; wherein the gas whose dew point has been decreased is returned into the furnace; wherein the heating zone and the soaking zone are in communication with each other through an upper portion of the furnace; wherein except for a communication region in the upper portion of the furnace, a partition wall is disposed so as to separate an atmosphere of the heating zone from an atmosphere of the soaking zone; wherein a connection part between the soaking zone and the cooling zone is disposed in the upper portion of the furnace; wherein suction ports through which the gas in the furnace is sucked so as to be introduced into the refiner are disposed in a portion of the cooling zone near the connection part between the soaking zone and the cooling zone and in an upper portion of the soaking zone; wherein feed ports through which the gas whose dew point has been decreased with the refiner is fed to the furnace are disposed at least in the connection part between the soaking zone and the cooling zone and in a lower portion of the soaking zone; and wherein a gas suction rate Qo