JPS5919019A - Method and apparatus for descaling - Google Patents

Abstract

PURPOSE:To remove oxidized scales generated on the surface of band steel material with saving energy, by jetting compressed air mixed with water on the surface of the band steel material. CONSTITUTION:When the tip end of a band steel 15 to be descaled comes near to a header 8, a solenoid valve 23 is opened and compressed air from an air compressor 20 (air source in the plant) is supplied to a mixer 19. At the same time, a part of the compressed air passed through the solenoid valve 23 for changing over air actuates a switch valve 18 to open side to open it. Consequently, water from a water supply pump 17 is supplied to the mixer 19 through a stop valve 3 and the valve 18. In the mixer 19, water is mixed with the compressed air that flows in the piping at high speed and jetted on the surface of the band steel 15 from a nozzle 7 of the header 8. The surface temperature of the band steel is lowered by water and air, thus forming the countless cracks in the scales on the surface, and the scales are stripped off. At the same time, compressed air blows off stripped scales. Thus, descaling is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hot strip steel rolling equipment, and particularly to hot IJIE rolling equipment.
E. This invention relates to a descaling method and apparatus for removing oxide scale generated on the surface of a stretched steel strip blade.

FIG. 1 is a system diagram showing the overall configuration of a conventional descaling device. The discharge side of the descaling pump device 1 is connected to a switching valve 5 through a piping 2, a cyst valve 3, and a strainer 4. The switching valve 5 is connected by a pipe 6 to a high-pressure water header 8 in which a high-pressure water nozzle 7 is provided.

Also, an on-off valve 9 and an orifice 10 bypassing the switching valve 5.
A bypass pipe 11 having a diameter is provided. Further, an accumulator 12 is connected to the pipe 2.

The high-pressure water header 8 having the high-pressure water nozzle 7 is connected to both sides of the steel strip C (sometimes referred to as fi/d4) 15, which is conveyed in the direction of the arrow in the figure by the table roller 13 and the pinch roller 14. is located close to.

In addition, after the strip steel 15 passes through the descheduling device 17, it enters the finishing rolling mill 16.

The conventional descaling device as described above uses high pressure water (100 to 150 kg/cn7) supplied to a high pressure water header 8 by a descaling pump device 1 from a nozzle 7 to the surface of a steel strip material in the hot rolling process. By spraying on the
Oxidized scale (hereinafter simply referred to as scale) generated on the surface of the steel strip 15 during the hot rolling process was removed. The mechanism of this scale removal will be explained below. Nozzle 7
When high-pressure water is sprayed onto the surface of the steel strip 15, the temperature of the scale on the surface of the steel strip is rapidly lowered, creating a temperature difference between the surface and the inside of the steel strip. As a result, there is a difference in the amount of shrinkage between the surface and the inside of the steel strip, causing countless cracks in the scale on the surface and peeling off of the scale. High-pressure water blows off the peeled scale to remove scale from the surface of the steel strip. but,
In such a conventional method, a large amount of water that has blown away the scale is splashed onto the surface of the steel strip, which lowers the temperature of the steel strip 15 itself more than necessary. Therefore, in order to maintain the appropriate temperature required for the next rolling process, the temperature drop in the descaling section (heat loss) is heated in the previous process, which is a separate heating furnace for the slab. I needed to leave it there. In addition, when high-pressure water is sprayed onto the surface of the steel strip 15 (fli), a film of steam of 100 to 1300 G is formed on the surface of the steel strip. Water is like spraying water into a swimming pool, and the energy of spraying tends not to be effective in removing scale. Therefore, in order to make the high-pressure water reach the surface of the steel strip 15, the water pressure is increased to 100 - A high positive pressure of 150 Kf/crl was required.

Moreover, in order to release such high-pressure water to atmospheric pressure each time descaling is performed, the descaling pump device 1
A large amount of energy was wasted to produce high-pressure water.

That is, in the conventional descaling device, a large amount of thermal energy is lost because the temperature of the steel strip 15 is lowered more than necessary, and a large amount of 1 air energy is required to create high-pressure water, so it is energy-consuming. The drawback is that it wastes a lot of energy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a descaling method and device that eliminates the above-mentioned drawbacks and achieves energy savings.

In the present invention, instead of conventional high-pressure water, a mixture of compressed air and water is sprayed in the form of a jet onto the steel strip surface through a nozzle to remove the optical surface scale of the steel strip.
The above objective is achieved by reducing the amount of water and water pressure.

An embodiment of the present invention will be described below with reference to the drawings, using the same reference numerals for the same parts as in the conventional example.

FIG. 2 is a system diagram showing an embodiment of the descaling method and apparatus of the present invention. The discharge side of the water supply pump device (volute pump) 17 is connected to a mixer 19 through a pipe 2, a stop valve 3, and an on-off valve 18'f. The discharge 111j of the air compressor (factory air source) 20 is connected to the mixer 19 through an air pipe 21, a stop valve 22, and an air switching solenoid valve (switching valve) 23. This mixer 19 is further connected to a header 8 having a nozzle 7. Further, the air exiting the air switching solenoid valve 23 is supplied to the on-off valve 18 through a pipe 24, and serves as a driving source for the on-off valve 18. A header 8 with a nozzle 7 is arranged close to the front surface IfIi of a steel strip 15 which is conveyed by table rollers 13 and pinch rollers 14. In addition, in the figure, air piping is shown with a broken line, and water piping is shown with a solid line. Further, the stop valve 22 and the solenoid valve 23 close the yarn path when maintaining each component on the header side. Furthermore, the stop valve 3 closes the yarn path when maintaining each component on the header side from the on-off valve 18.

Next, the operation of this embodiment will be explained. First, when the tip of the steel strip 15 to be descaled approaches the header 8, a solenoid (not shown) of the air switching solenoid valve 23 is energized, and the solenoid valve 23 opens.

Therefore, the compressed air from the air compressor 20 passes through the stop valve 22 and the air switching solenoid valve 23 to the mixer 1.
9. At the same time, air switching solenoid valve 2
A part of the compressed air exiting from the valve 18'f operates to open the on-off valve 18'f. Therefore, water from the water supply pump device 17 is supplied to the mixer 19 through the stop valve 3 and the on-off valve 18. In this pipe 19, water is mixed into the compressed air flowing through the piping at high speed and is sprayed from the nozzle 7 of the header 8 onto the surface of the steel strip 150.

fE Condensed air mixed with water forms a jet of steel strip 15
When sprayed onto the surface of the steel strip 15, both water and air lower the temperature of the surface of the steel strip 15, creating numerous cracks in the scale on the surface and causing it to peel off. At the same time, descaling is performed by blowing off the peeled off scale with the energy generated when compressed air is released under atmospheric pressure. Of course, the jet water accelerated by compressed air and injected through the nozzle 7 also blows off the exfoliated scale and performs descaling.

Compressed air and water are injected from the nozzle 7 continuously while the steel strip 15 passes through the header 8. When the tail end of the steel strip 150 passes through the header 8, the air switching solenoid valve 23 is energized. At the same time, the air pressure on the outlet side of the air switching valve 23 disappears, so the on-off valve 18 is not closed at the same time, and the water supply is also stopped.

With this, a series of descaling operations is completed, and each time the steel strip 15 passes, the above-described series of operations are repeated to perform descaling.

According to this embodiment, since a mixture of water and air is used for descaling, the amount of water sprayed onto the steel strip 15 can be reduced to 1/10 or less compared to the conventional method, and a large amount of water can be sprayed onto the steel strip 15. The water does not lower the temperature of the steel strip 15 more than necessary, and therefore the amount of heating of the steel strip 15 in the heating furnace in the previous step is reduced, which has the effect of preventing energy consumption. Moreover, the water supplied is small,
Since compressed air is also sprayed together with water, water droplets, etc. are formed on the surface of the steel strip 15.
41 sections, which has the effect of significantly reducing the energy consumed by the water supply pump device 17. Note that the air compressor 20 sends out compressed air at a pressure of about 10 kg/cnF, so the energy consumed by the air compressor 20 is not that significant, and even if you combine both, the energy consumption will be lower than that of the conventional one. 1/1o
It has the effect of reducing: Furthermore, the piping for the entire device is
Since only a pipe that can withstand a pressure of 10 Kp/i is required, the equipment cost and maintenance cost can be reduced to a fraction of that of conventional water pipes of 100 to 150 Kf/cmt. Therefore, even if air system equipment is added, the cost of this embodiment can be reduced to a fraction of that of the conventional equipment.

In addition, in the above-mentioned embodiment, an example was shown in which the present invention was applied to the finishing scale breaker on the input side of the finishing mill 16 of a hot strip steel rolling facility, but it can also be applied to a rough rolling facility, a blooming facility, a bar rolling facility, and a long strip rolling facility. It goes without saying that the same effect can be obtained even when the present invention is applied to a descaling device for wire rod rolling equipment. Further, in the above embodiment, a 2-header system has been described, but it is also possible to use a 1-header system or a 3-header system. Further, in the above embodiment, an example was explained in which the air compressor 20 and the water supply pump device i17 were used as the energy source for descaling, but the same device can be obtained by using a factory air source and roll cooling water g instead. can be configured. This currently means that
It is effective when all conventional descaling equipment using high-pressure water is modified to the descaling equipment of the present invention that protects against both water and air.

As described above, according to the present invention, it is possible to generate n energy by injecting compressed air mixed with water onto a steel strip.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an example of the structure of a conventional descaling method and device, and FIG. 2 is a system diagram showing an embodiment of the descaling method and device of the present invention. 7... Nozzle, 8... Header, 17... Water supply pump device, 18... Open/close valve, 19... Mixer, 20...
・Air combo 1st l otsuya 2nd 6

Claims (1)

[Claims] 1. In a descaling method for removing oxidized scale generated on the surface of a steel strip during the rolling process, the surface of the steel strip includes:
A descaling method characterized by injecting compressed air mixed with water. 2. In a descaling treatment line that removes oxidized scale generated on the surface of steel strip material during the rolling process, a device for supplying compressed air, a device for supplying water, a mixing device for mixing the water into the compressed air, and a compressor. 1. A descaling device comprising: a nozzle that injects air mixed with water onto the surface of the steel strip. 3. A switching valve that turns on and off the flow of compressed air is inserted between the compressed air supply device and the mixing device, and an on-off valve that opens and closes by introducing compressed air on the outlet side of this switching valve, Claim 2: The device is inserted between a water supply device and a mixing device, and simultaneously opens and closes the switching valve depending on the position of the steel strip with respect to the nozzle.
Descaling device f described in section f.