Continuous annealing device and continuous hot-dip galvanising device for steel strip

Patent metadata

Field	Value
Publication number	US-9957585-B2
Application number	US-201414761724-A
Country	US
Kind code	B2
Filing date	Feb 18, 2014
Priority date	Feb 25, 2013
Publication date	May 1, 2018
Grant date	May 1, 2018

Abstract

A steel strip continuous annealing device has a vertical annealing furnace 10 in which a heating zone 14 , a soaking zone 16 , and a cooling zone 18 are arranged in this order, and anneals a steel strip P passing through the zones 14, 16 , and 18 in the order while being conveyed in the vertical direction in the vertical annealing furnace 10 . The heating zone 14 , the soaking zone 16 , and the cooling zone 18 communicate through an atmosphere separation portion 36 . One of a gas delivery port 38 and a gas discharge port 40 is positioned in an upper part and the other one of the gas delivery port 38 and the gas discharge port 40 is positioned in a lower part in each of the heating zone 14 , the soaking zone 16 , and the cooling zone 18.

First claim

The invention claimed is:

1. A steel strip continuous annealing device that has a vertical annealing furnace in which a heating zone, a soaking zone, and a cooling zone are arranged in the stated order, and anneals a steel strip passing through the zones in the order while being conveyed in a vertical direction in the vertical annealing furnace, comprising:
a first throat extending in a lateral direction and provided between the heating zone and the soaking zone;
a second throat extending in the lateral direction and provided between the soaking zone and the cooling zone;
an atmosphere separation portion including at least one of a partition plate, a seal roll, a damper, and a gas separation device forming an air curtain;
a gas delivery port for introducing gas into the vertical annealing furnace; and
a gas discharge port for discharging gas from the vertical annealing furnace,
wherein the heating zone, the soaking zone, and the cooling zone communicate through the first throat and the second throat,
the atmosphere separation portion is provided in each of the first throat and the second throat to separate an atmosphere in the heating zone from an atmosphere in the soaking zone and to separate an atmosphere in the soaking zone from an atmosphere in the cooling zone,
the gas delivery port and the gas discharge port are provided in each of the heating zone, the soaking zone, and the cooling zone,
one of the gas delivery port and the gas discharge port is positioned in an upper part and the other one of the gas delivery port and the gas discharge port is positioned in a lower part in each of the zones,
the steel strip continuous annealing device is configured to be switchable between a first mode and a second mode,
in the first mode the gas delivery port and the gas discharge port provided in each of the heating zone, the soaking zone, and the cooling zone are opened so as to switch the atmosphere in each of the zones, and
in the second mode the gas delivery port provided in each of the zones is opened and the gas discharge port in each of the zones is closed for operation, and wherein
the steel strip continuous annealing device is switched to the first mode when a dew point inside the vertical annealing furnace reaches a threshold temperature, and to the second mode when the dew point inside the vertical annealing furnace is below the threshold temperature.

2. The steel strip continuous annealing device according to claim 1 ,
wherein a preheating zone is arranged upstream of the heating zone, a third throat extending in the lateral direction is provided between the preheating zone and the heating zone, the preheating zone and the heating zone communicate through the third throat, the atmosphere separation portion is also provided in the third throat to separate an atmosphere in the preheating zone from an atmosphere in the heating zone, and one of the gas delivery port and the gas discharge port is positioned in the upper part and the other one of the gas delivery port and the gas discharge port is positioned in the lower part in the preheating zone.

3. The steel strip continuous annealing device according to claim 1 ,
wherein the gas delivery port is positioned in the lower part and the gas discharge port is positioned in the upper part in all of the zones.

4. The steel strip continuous annealing device according to claim 3 ,
wherein a flow rate Q (m 3 /hr) per gas discharge port in each zone satisfies conditions of Expression (1) and Expression (2)
Q> 3.93× V   Expression (1)

Q> 1.31× V 0   Expression (2)

where V 0 (m 3 ) is a volume of the zone, and V (m 3 ) is a volume of the zone per pair of gas delivery port and gas discharge port.

5. The steel strip continuous annealing device according to claim 1 ,
wherein a length of each of the zones is 7 m or less.

6. A continuous hot-dip galvanising device comprising:
the steel strip continuous annealing device according to claim 1 ; and
a hot-dip galvanising device that hot-dip galvanises the steel strip discharged from the cooling zone.

Assignees

• Jfe Steel Corp

Inventors

• Takahashi Hideyuki
• Nara Tadashi

Classifications

• C21D9/56

  Continuous furnaces for strip or wire · CPC title

• C21D9/573 Primary

  with cooling · CPC title

• C21D9/005

  Furnaces in which the charge is moving up or down (for wire, strip C21D9/54) · CPC title

• C21D9/561

  with a controlled atmosphere or vacuum · CPC title

• C21D1/26

  Methods of annealing · CPC title