| 摘要 |
The invention provides a continuous annealing furnace which can lower quickly the dew point of a furnace atmosphere to a level suited for steady operation and which allows the atmosphere to stably maintain a low dew point causing little problems in terms of the occurrence of pick-up defects and damages to furnace walls, and also provides a continuous annealing method for steel strips which involves the annealing furnace. The furnace is a vertical annealing furnace including a heating zone and a soaking zone without any partition wall therebetween and is configured such that part of a gas in the furnace is suctioned and introduced into a refiner outside the furnace that is equipped with an oxygen removal device and a dehumidifier to lower the dew point by the removal of oxygen and water in the gas, and the gas with the lowered dew point is returned into the furnace. The furnace has furnace-to-refiner gas suction openings disposed in a lower portion of a joint between the soaking zone and a cooling zone and in the heating zone and/or the soaking zone except a region extending 6 m in a vertical direction and 3 m in a furnace length direction both from a steel strip inlet at a lower portion of the heating zone. The furnace has refiner-to-furnace gas ejection openings disposed in a region in the joint between the soaking zone and the cooling zone, the region being located above the pass line in the joint, and in a region in the heating zone located above 2 m below the center of upper hearth rolls in the vertical direction. |
