Continuous annealing furnace for steel strip, continuous annealing method, continuous galvanizing apparatus and method for manufacturing galvanized steel strip (as amended)

摘要

Provided is a vertical annealing furnace, in which a heating zone and a soaking zone are communicated with each other in the upper part of the furnace, in which a part of the furnace other than the communicated parts is separated by a dividing wall, in which part of the furnace gas is suctioned into a refiner having a deoxidation device and a dehumidification device which is placed outside the furnace to decrease the dew point of the gas by removing oxygen and moisture from the gas and such that the resultant gas having a decreased dew point is returned into the furnace, in which a gas suction port into the refiner is located in the lower part of the connection part between the soaking zone and the cooling zone and in which one or more gas suction ports are located in the parts of the heating zone and/or the soaking zone outside of an area within 6 m in the vertical direction and 3 m in the longitudinal direction of the furnace from the steel strip entrance in the lower part of the heating zone.

主权项

1. A continuous annealing furnace for a steel strip, the furnace being a vertical annealing furnace comprising a heating zone, a soaking zone, a cooling zone located in this order through which a steel strip is transferred in the up-and-down direction, the connection part between the soaking zone and the cooling zone being located in the upper part of the furnace, the heating zone and the soaking zone being communicated with each other in the upper part of the furnace, a dividing wall being placed in a part of the furnace other than the communicated parts in the upper part of the furnace to physically separate the heating zone and the soaking zone, an atmospheric gas being fed into the furnace from the outside of the furnace, and the furnace gas being discharged through a steel strip entrance in the lower part of the heating zone while a refiner having a deoxidation device and a dehumidification device which is placed outside the furnace such that part of the furnace gas is suctioned into the refiner to decrease the dew point of the gas by removing oxygen and moisture from the gas and the resultant gas having a decreased dew point is returned into the furnace through a gas delivery port, wherein a gas suction port from the furnace into the refiner is located at a position where a flow channel narrows at a throat part or a position in the vicinity of seal rolls in the lower part of the connection part between the soaking zone and the cooling zone and wherein one or more gas suction ports are located in the parts of the heating zone and/or the soaking zone outside of an area within 6 m in the vertical direction and 3 m in the longitudinal direction of the furnace from the steel strip entrance in the lower part of the heating zone.