JPS61207564A - Galvannealing device - Google Patents

Abstract

PURPOSE:To heat a strip uniformly and to economize on energy for a device by connecting a heating and soaking zone provided with direct firing type burners and a holding body using the waste gas of the burners as a heat source to the outlet side of the 1st heating zone provided with an induction heater. CONSTITUTION:The heating and soaking zone 8 disposed with the direct firing burners 10 in a refractory heat insulating material 9 is provided via a water cooling jacket to the outlet side of the 1st heating zone 4 disposed with an induction coil 6 in a heat radiating wall. The direct firing burners 10 are alternately provided to face the strip and heat uniformly the strip. The heated strip is held in a holding furnace and is thereby alloyed. The heat of the waste gas generated by the direct firing burners 8 of the heating and soaking zone 8 is utilized for the heat source of the holding furnace 13. The alloyed strip is conveyed to an air cooling zone and a mist cooling zone. The temp. difference in the transverse direction of the strip and particularly the overheating at the edge part occurring in the induction heating in the galvannealing device are thus effectively eliminated.

Description

[Detailed Description of the Invention] (Industrial Application Field) Conventionally, for example, in the production of galvanized iron sheets, a strip is plated in a galvanizing bath, and then this strip is subjected to a galvanealing device consisting of a heating zone and a heating zone. There is a so-called alloying treatment method in which zinc is passed through to form an alloy layer of zinc and a base steel sheet.

As heating means for the heating zone, a direct heating method in which the strip is heated using a cup burner or the like, a convection heating method in which the strip is heated by forcibly blowing hot air, and an induction heating method are adopted.

However, the direct heating method requires a large number of burners, resulting in a heavy structure of the equipment itself, and there are problems in that burner operation and maintenance are troublesome.

In the convection heating method, heating is performed by convection of hot air, which not only requires a large circulation fan and combustion chamber of the burner, but also causes zinc vapor to accumulate on the circulation fan, making maintenance troublesome. Since the transmission coefficient cannot be made large, there is a problem that the device becomes long and has a heavy structure.

On the other hand, the induction heating method has advantages such as rapid heating, better thermal efficiency, and the ability to shorten the length of the equipment compared to the first two methods, but it has the disadvantage of overheating the etched area and The problem was that a separate heat source was required for each.

Therefore, an object of the present invention is to study the advantages and disadvantages of the above-mentioned conventional systems, and to provide a galvaneal device that takes advantage of each of the advantages.

(Means to Solve the Problems) In order to achieve the above object, the present invention provides a heating system equipped with a direct-fired burner on the outlet side of a first heating zone equipped with an induction heater.・Along with the connecting rack for the soaking zone,
The structure is such that a heating and soaking zone uses the exhaust gas from the heating and soaking zone as a heat source connected to the outlet side of the heating and soaking zone.

(Example) Next, the present invention will be explained according to the drawings which are one example.

FIG. 1 shows a production line for galvanized iron plates equipped with a galvanil device T according to the present invention, where 1 is an annealing furnace, 2 is a plating bath, 3 is a heating zone, 20 is an air cooling zone, and 30 is a mist cooling zone. It is.

The galvaneal device T generally includes a first heating zone 4, a heating/soaking zone 8, and an insulating zone I3 consisting of a duct 12, an air cooling zone 20, and a mist cooling zone 30.

As shown in FIG. 2, the first heating zone 4 has a structure in which an induction coil 6 is placed between a heat insulating wall 5 and a strip W, and a water cooling jacket 7 is provided on the outlet side of the first heating zone 4.
A heating/soaking zone 8 made of fireproof heat insulating material 9 is provided through the heating/soaking zone 8. 1O is an open flame burner installed in the heating/soaking zone 8, and as shown in FIGS. 2 and 3, the strip W to be processed is
(
It is J. Note that 11 is a dilution air adjustment damper that introduces outside air into the duct 12 to adjust the heat retention temperature (ambient temperature inside the duct 12).

Furthermore, one side wall 14 of the first heating zone 4 and the heating/soaking zone 8 has a double door structure, as shown in FIG. Set up (
It is possible to move to the J rail I5. That is,
To prevent strip breakage when the line is stopped, and when igniting the burner at the start of operation, it can be moved to the left or right as shown in Fig. 4 to enable line-in or line-out.

In addition, 16 is a molten zinc coating amount adjustment nozzle.

With the above configuration, the strip W heat-treated in the annealing furnace 1 is immersed in molten zinc in the plating bath 2, and then the basis weight is adjusted by spraying N2 gas or combustion exhaust gas from the nozzle 16. It is rapidly heated in the heating zone 4 by the induction coil 6. In this way, the strip W heated in the first heating zone 4 is subsequently heated in the heating/soaking zone 8, but as described above, in the first heating zone 4, the edge portion of the strip W is Since it is superheated, the direct fire burner IO heats the strip W except for both edges, thereby heating the strip W uniformly.

That is, the final heating temperature of the strip W is set to 550 to 60
If the temperature is 0°C, the strip W in the first heating zone 4 is heated to 500°C.
When heated to 550°C, both edge parts are overheated by 50°C or more, so in order to eliminate this temperature difference in the width direction of the strip W, the parts of the strip W other than both edges are heated in the heating/soaking zone 8. This is to uniformly heat the winter trip W to the final heating temperature.

In addition, depending on the width of the strip W to be processed, it goes without saying that the direct fire burner lO may be thinned out to prevent both edges of the strip W from overheating, and the direct fire burner lO may be thinned out to the maximum width of the strip W. It is also possible to prevent overheating of the edge portion by providing the fuel in a straight line and varying the amount of combustion on both sides.

The strip W heated as described above is heat-retained (550 to 600°C) and alloyed in the heat-retaining zone 13, but the heat source of the heat-retaining zone 13 is generated in the heating/soaking zone 8. Utilizes exhaust gas heat from direct burner IO. Note that the temperature of the insulation zone 13 is adjusted by opening and closing the damper 11.

In this way, the alloyed strip W is transferred to the air cooling zone 2.
0, it is transported to a predetermined location via the mist cooling zone 30.

In the above embodiment, the heating/soaking zone 8 is of a direct heating type in which heating is performed by the direct flame burner IO, but the high temperature exhaust gas from the direct flame burner 10 is blown onto the strip W from a nozzle header (not shown). A convection heating method may also be used.

In this case as well, a structure can be used to prevent overheating of both edge parts of the strip W, for example, a structure in which the nozzle header is divided into multiple parts in the width direction of the strip W and the amount of spray is controlled in the center part and both sides respectively. It goes without saying that you should.

Further, a heating means such as a burner is provided in the heating/soaking zone 13, and when the amount of heat from the exhaust gas from the heating/soaking zone 8 is insufficient, the temperature of the heating zone 13 is maintained by the heating means. Good too.

(Effects of the Invention) As is clear from the above explanation, according to the galvaneal device according to the present invention, when heating a galvanized strip to the alloying treatment temperature, the initial heating is performed by induction heating, and the final heating is performed using a direct flame burner. Because direct heating or convection heating is used, it effectively eliminates the temperature difference in the width direction of the strip that occurs due to induction heating, especially the overheating phenomenon at the edge, and even though induction heating is used, ,
Uniform heat treatment is possible, and the exhaust gas from the direct burner can be used as a heat source for the heat storage zone for alloying treatment, resulting in energy savings.

In addition, the number of burners is required to be small because heating by the direct flame burner is only in the final heating region.Furthermore, with the convection heating method, the circulation fan only needs to be small, which improves operability and maintainability. The heating zone equipped with a direct fire burner is short, and this combined with induction heating for initial heating not only significantly improves responsiveness, but also reduces heat loss during temperature rise and fall.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a production line for galvanized iron plates using the galvanil device according to the present invention, Fig. 2 is a sectional view of the heating zone, and Fig. 3 is a sectional view taken along the line ■-■ in Fig. 2. , FIG. 4 is a sectional view showing the relationship between the movement of the heating zone and the strip. T: Galvanil device, 4: First heating zone, 6: Induction coil, 8: Heating/soaking zone, IO direct fire burner, 12:
...Duct, 13..Insulation zone, W. Strip.

Claims (1)

[Claims] (1) A heating/soaking zone equipped with a direct-fired burner is connected to the exit side of the first heating zone equipped with an induction heater, and the exhaust gas from the heating/soaking zone is connected to the exit side of this heating/soaking zone. A galvanil device is characterized in that it is connected to an insulating zone that uses a heat source as a heat source.