JP3058933B2 - Pickling equipment for annealing stainless steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stainless steel sheet annealing and pickling apparatus for annealing and pickling a rolled stainless steel sheet.

[0002]

2. Description of the Related Art Generally, an operation of annealing and pickling in which a stainless steel sheet hardened by rolling is heated and softened and an oxide film on the surface is removed is performed in an annealing pickling facility. Two methods in the conventionally used annealing and pickling equipment will be described with reference to FIGS. 3 and 4. FIG.

FIG. 3 shows an example of what is called a horizontal annealing and pickling facility. In FIG. 3, 11 is a stainless steel plate, 12 is a heating furnace, 13 is a burner (long frame burner), 14 is a cooling zone, 15 is pickling equipment, 16 is combustion exhaust gas, and 17 is pre-tropical. Stainless steel plate 11
It enters the annealing pickling equipment from the position of the inlet A, is preheated to a predetermined temperature by the combustion exhaust gas 16 in the pre-tropical zone 17, and then is subjected to radiant heating by the long flame burner 13 while continuously passing through the heating furnace 12. The temperature is raised to a temperature required for annealing. After heating the stainless steel plate, the flue gas 16 passes through the heating furnace 12 and the pre-tropical zone 17,
Released outside the furnace. After being kept at the annealing temperature for a while, it enters the cooling zone 14 and is cooled. Next, the stainless steel sheet 11 after cooling enters the pickling equipment 15 to remove scale (oxide film) formed on the surface during the annealing process, performs descaling, and then is carried out from the outlet B and exits the equipment.

FIG. 4 shows an example of an annealing and pickling facility called a hard type. In FIG. 4 , 21 is a stainless steel plate,
22 is a heating furnace, 23 is a burner (cup burner), 2
4 is a cooling zone, 25 is a pickling facility 26 is a combustion exhaust gas, and 27 is a pre-tropical zone. Unlike the horizontal annealing and pickling equipment, the rigid-type annealing and pickling equipment has a heating furnace 22 installed vertically, and the stainless steel plate 21 is heated and cooled while moving vertically. The treatment process is the same as that of the horizontal type.
Is preheated to a predetermined temperature, and then radiantly heated by the cup burner 23 in the heating furnace 22, and heated to the annealing temperature. The combustion exhaust gas 26 after heating the steel plate 11 passes through the heating furnace 22 and the pre-tropical zone 27 and is discharged from the lower end opening of the pre-tropical zone 27 to the outside of the furnace. The stainless steel plate 21 is then cooled in the cooling zone 24, then descaled in the pickling equipment 25, discharged from the outlet B, and exits the equipment.

[0005]

However, the above-mentioned conventional annealing and pickling equipment has the following problems.

[0006] In a vertical furnace and a horizontal furnace, a stainless steel plate is heated by a burner combustion gas in a heating furnace. Here, the heating furnace length is determined based on the maximum throughput of the equipment, that is, the maximum TV value (thickness × running speed). Therefore, the heating furnace length is a necessary and sufficient length at the maximum TV value. But generally less than the maximum TV value
There was also an operation at the V value, and even in this case, the steel plate was heated with the same furnace length.

[0007] Therefore, conventionally, in the operation of the maximum TV value or less, since the steel sheet is heated through the entire length of the heating furnace after reducing the burner load, the heating rate,
That is, (heating effective length / TV value) increased with a decrease in TV value. The heating rate is set at T.sub.2 from the viewpoint of the rate of temperature rise of the stainless steel plate, pickling properties and thermal efficiency.
It is constant irrespective of the V value and forms on the surface of stainless steel plate.
Constant the amount of scale generated by annealing
Pickling without affecting the pickling time in the pickling process
Improve efficiency and improve overall efficiency
Although desirable, the conventional method has a problem that the heating rate changes depending on the TV value as described above.

On the other hand, from the viewpoint of keeping the heating rate constant, when the TV value decreases, the conventional method has a problem that the heating furnace length becomes longer than necessary.

The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a stainless steel sheet annealing and pickling facility which stably performs an annealing and pickling operation on a stainless steel sheet and greatly improves the thermal efficiency thereof. Aim.

The stainless steel sheet annealing and pickling equipment according to the present invention, which achieves the above object, conveys the stainless steel sheet in the order of a pre-tropical zone, a heating zone, and a cooling zone, anneals it, and then performs pickling in a pickling tank. In the annealing and pickling equipment for stainless steel sheets, the heating zone is divided into a plurality of heating zones, and the on / off control of a heating combustion burner is performed for each division zone in accordance with the TV value of the stainless steel sheet, changing the effective furnace length of the heating furnace, characterized in that substantially comprises a control means for maintaining a constant heat computing rate.

[0011]

The maximum throughput of a stainless steel plate, that is, the maximum T
To accommodate operation of the TV values below V value, the furnace properly several zones divided in conveyance direction of the stainless steel plate, TV
By controlling the burner combustion ON-OFF according to the value, the effective furnace length of the heating furnace is changed so that the heating rate becomes constant or almost constant. Thus, the stainless steel sheet can be annealed while keeping the temperature rising rate (° C./sec) and the annealing time (= in-furnace time in the effective heating length) constant or almost constant. As a result, the amount of scale generated by annealing generated on the surface of the stainless steel plate is made constant, and the pickling time in the pickling process, which is a process after annealing, is not affected. Therefore, as a process of continuously performing the annealing and pickling, the annealing and the pickling of the steel sheet can be stably performed regardless of the TV value. Burner ON-OF
The F control can be reduced is burner combustion number in the same TV value, strip heat input is increased per a single burner can be improved heat efficiency.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below.

FIG. 1 is a schematic diagram of a vertical annealing pickling facility for stainless steel sheets according to an embodiment of the present invention.

As shown in FIG. 1, the stainless steel sheet annealing and pickling equipment according to the present embodiment is provided with a plurality of burners 102 opposed to each other in the conveying direction of the stainless steel sheet 101.
Vertical heating furnace 103 provided with
01 is provided on the upstream side in the conveying direction of the
, A pre-tropical zone 105 for preheating the stainless steel plate 101 during transportation, a cooling zone 106 for cooling the stainless steel plate 101 heated by the burner 102, and a stainless steel plate 10 after the cooling.
1. Pickling tank 1 for removing scale generated during the above annealing
07. Here, the heating furnace 103
The inside is divided into a plurality of heating zones A, B, and C, and a fuel cutoff valve 108 for shutting off fuel supplied to the burner 102 and combustion air is interposed in a fuel pipe 109 for each of the heating zones A to C. ing. The fuel cutoff valve 108 is controlled by a signal from a control unit to perform ON-OFF control for each of the heating zones A, B, and C according to the TV value (plate thickness × running speed) of the stainless steel plate 101.

Therefore, the effective heating length in the heating furnace 103 can be changed by controlling the ON / OFF control of the fuel and the combustion air supplied to the burner in accordance with an instruction from the control means, and the heating rate can be substantially constant. (Effective heating length /
(TV value) can heat the stainless steel plate 101. The range in which the burner combustion is turned off includes a range in which conventional burning is performed in order to avoid burner burnout.

In the above configuration, the conveyed stainless steel plate 101 enters the present facility from the inlet A, is preheated to about 300 to 400 ° C. in the pre-tropical zone 105, and then burners 102.
Into the heating furnace 103 having In the heating furnace 103, a temperature (for example, N
The temperature is raised to about 1100 ° C. in the case of an i-type stainless steel sheet and to about 800 ° C. in the case of a Cr-based stainless steel sheet), where the stainless steel sheet 101 is kept at a constant temperature for a certain time. Thereafter, the cooling water enters the cooling zone 106, further enters the pickling tank 107, where the scale (oxide film) generated during the above-described annealing is removed, and then conveyed from the outlet B to the outside of the equipment.

Here, the divided heating zones A, B, C
Burner 102 provided is attached to branch from the same fuel pipe 109 to allow ON-OFF control of the batch, the fuel barrier Danben 10 upstream of the fuel pipe 109
8 are provided. The fuel cutoff valve 108 is controlled by a fuel control unit (not shown) that performs ON-OFF control of fuel or the like in accordance with the TV value (steel plate thickness × running speed) of the stainless steel plate. At the maximum processing amount of the equipment, that is, at the maximum TV value (steel plate thickness × running speed), the fuel shut-off valves 108 in all zones are opened, all the burners 102 are turned on, and the stainless steel is turned over the entire length of the heating furnace 103. The steel plate 101 is heated. Also, when the processing amount is lower than the maximum TV value, according to the TV value,
The fuel shutoff valves 108 of the heating zones A, B, and C are appropriately closed and the burner 102 is turned off so that the heating rate (effective heating length / TV value) becomes constant or almost constant.
The effective heating length of the heating furnace 103 is adjusted. For example, when the TV value is 2/3 of the maximum value, 1/3 of the heating furnace length
The heating rate is maintained at a constant value by turning off the burner in the zone corresponding to (2) and setting the effective heating amount of the heating furnace to 2/3 of the total length. The air supplied to the burner from which the fuel has been shut off may be shut off in the same manner as the fuel or may be supplied with a minimum flow rate necessary for preventing burner nozzle burnout.

As described above, the inside of the heating furnace 103 is divided into zones, and the effective heating length is changed by the control means, so that the heating rate (° C./sec) of the stainless steel sheet and the annealing time (= effective heating length) The steel plate can be annealed while maintaining the furnace time constant or almost constant. This enables annealing so that the amount of scale generated on the surface of the stainless steel plate is substantially constant, and does not affect the pickling time in pickling after annealing.

Therefore, the process of continuously performing the annealing and pickling has a great advantage in that the steel sheet can be stably annealed and pickled regardless of the TV value. further,
Compared to the conventional system, the same T
Since the number of burners burned at the V value can be reduced, the merit that the heat input amount of the strip per single burner increases and the thermal efficiency can be improved can be achieved at the same time.

Next, another embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic view of an annealing and pickling facility according to another embodiment of the present invention.

In FIG. 2, reference numeral 201 denotes a stainless steel plate;
Is a burner, 203 is a heating furnace, 204 is a combustion exhaust gas, 20
5 is pre-tropical, 206 is a cooling zone, 207 is a pickling tank, 208
Denotes a fuel cut-off valve, 209 denotes a fuel pipe, and A, B, C and D denote heating zones, respectively, and the process is the same as that of the above-described vertical annealing equipment shown in FIG.

As shown in the figure, the stainless steel sheet annealing and pickling equipment according to the present embodiment is a horizontal type equipment, and is divided into heating zones A to D in the same manner as the vertical annealing and pickling equipment described above. The effective heating length of the heating furnace 203 is changed by performing on-off control of the burner combustion control corresponding to the TV value by a combustion control means (not shown) every time, so that the heating rate is constant or almost constant.

[0023]

As described above in detail with the embodiments,
Since the stainless steel sheet annealing and pickling equipment of the present invention can divide the heating zone into zones and appropriately change the effective heating furnace length according to the TV value, the heating rate can be changed regardless of the processing amount of the stainless steel sheet, that is, the TV value. The toting rate can be kept constant. Therefore, the following effects are obtained. Since the heating rate is constant, that is, the annealing time can be constant, the scale generated on the steel sheet surface is almost constant. Therefore, there is an effect that the pickling time as a post process can be maintained constant. Therefore, the basic unit of pickling can be improved as compared with the conventional method. When the TV value is small, burner combustion is turned off to reduce the effective heating length, and the number of burners is reduced. As a result, the amount of heat input to the strip per burner was increased, and the thermal efficiency of the heating furnace could be improved.
As described above, the economic effect on the operation cost of the equipment is very large.

[Brief description of the drawings]

FIG. 1 is a schematic view of a stainless steel sheet annealing and pickling equipment configuration according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a stainless steel sheet annealing pickling equipment configuration according to another embodiment of the present invention.

FIG. 3 is a schematic view showing a conventional horizontal facility configuration.

FIG. 4 is a schematic diagram showing a conventional vertical equipment configuration.

[Explanation of symbols]

 101, 201 stainless steel plate 102, 202 burner 103, 203 heating furnace 104, 204 flue gas 105, 205 pre-tropical 106, 206 cooling zone 107, 207 pickling tank 108, 208 fuel cutoff valve 109, 209 fuel pipe A, B, C, D heating zone

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Kasai 4-22, Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Works (72) Inventor Kosuke Yamashita 4-chome Kannonshinmachi, Nishi-ku, Hiroshima-shi, Hiroshima 6-22 Mitsubishi Heavy Industries, Ltd.Hiroshima Research Institute (72) Inventor Kenji Shinya 4-2-2 Kanon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd.Hiroshima Research Institute (72) Inventor Toshio Kojima Kashima-gun, Kashima-gun, Ibaraki Prefecture Kashima Plant, Japan Stainless Steel Co., Ltd. Kashima Factory (72) Inventor Toshimitsu Kobayashi 2 Kashima Town Kashima-cho, Kashima-gun, Ibaraki Prefecture Kashima Factory, Japan Stainless Steel Co., Ltd. -79795 (JP, A) JP-A-3-24286 (JP, A) JP-A-2-205692 (JP, A) 1-17887 (JP, B2)

Claims (1)

(57) [Claims] 1. A stainless steel sheet annealing and pickling facility in which a stainless steel sheet is transported and annealed in the order of a pre-tropical zone, a heating zone, and a cooling zone, and then pickled in a pickling tank. It is divided with made for each zone, corresponding to the TV value of the stainless steel sheet with a heating burner on and off control for each of the divided zones, substantially arsenide computing rate by changing the effective furnace length of the heating furnace An annealing and pickling facility for stainless steel sheets, comprising a control means for maintaining a constant value.