KR101138180B1 - Apparatus for removing residual pickling solution - Google Patents

Abstract

An object of the present invention is to provide a device configured to effectively remove the pickling liquid remaining on the upper and lower surfaces of the steel sheet by installing a nozzle for injecting air in a predetermined position inside the connecting passage connecting the pickling section and the washing section.

Residual pickling liquid removing apparatus according to the present invention for achieving the above object, the upper and lower surfaces of the hot-rolled steel sheet in the mouth of the hot-rolled steel sheet is introduced into the connection passage connecting the pickling section and the washing section of the pickling device of the hot rolled steel sheet Air spray nozzles for spraying air having an injection angle of 15 to 45 ° in the pickling section direction based on a line perpendicular to the surface of the hot rolled steel sheet are installed in one or two or more stages, and the hot rolled steel sheet is discharged. An air curtain nozzle is installed on the exit side to inject air perpendicular to the upper and lower surfaces of the hot rolled steel sheet to form an air curtain that prevents water vapor from flowing into the pickling section.

Pickling section, washing section, residual pickling liquid, air spray

Description

Apparatus for removing residual pickling solution

1 is a schematic diagram of pickling and washing sections in a hot rolled line;

2 is a detail view of a flush section in a hot rolled line.

Figure 3 shows a residual pickling solution removal apparatus according to the present invention.

[Description of Reference Numerals]

1: hot rolled steel sheet 2: pickling section

3: flush section 4, 5: double ringer roll

6: connecting passage 7: ringering roll

8: first flush nozzle 9: second flush nozzle

10: third flush nozzle 11: fourth flush nozzle

12: First flush tank 13: Second flush tank

14: third flush tank 15: fourth flush tank

16: pure water tank 21: hot rolled steel sheet

22: Pickling section 23: Washing section

24, 25: double ringer roll 26: connecting passage

27: air spray nozzle 28: air curtain nozzle

The present invention relates to a residual pickling liquid removal device, and more particularly, in the pickling process of a hot rolled steel sheet, by spraying air on the surface of the steel sheet in the connection passage connecting the pickling section and the washing section to effectively remove the residual pickling liquid. It relates to a device that can.

1 is a view showing a conventional hot rolled sheet pickling process. The process of pickling a hot rolled steel sheet largely washes the surface of the steel sheet with a pickling solution (usually about 80 ° C., 18% hydrochloric acid solution) to remove scales, etc., and a predetermined pressure is applied to the surface of the steel sheet passing through the pickling section. It consists of a washing section (3) for spraying water to remove the pickling liquid, the pickling section (2) and the washing section (3) are interconnected by a connecting passage (6). The inside of the pickling section 2 has an acidic atmosphere as a whole by the pickling fume generated by evaporation of the hot pickling solution at high temperature, whereas the pickling section 3 is filled with only water vapor and has a neutral atmosphere.

Inside the pickling section 2, a double ringer roll 4, 5 is installed as the last step of the pickling section 2, which is squeezed by pressing the steel plate up and down. After pickling, pickling liquid remaining on the steel sheet is removed. That is, when the steel sheet 1 moves through the pickling section and moves the water washing section, the surface of the steel sheet is squeezed by using the front doubling ring 4 and the rear doubling ring 5 to prevent excessive acid inflow. . The hot rolled steel sheet 1 drawn into the washing section 3 is sprayed with a large amount of water on the upper and lower surfaces of the steel sheet through the washing nozzles 8 and 9 to wash the bare steel sheet whose scale is removed by pickling. The water after washing with water is contained in the washing tanks 12 and 13 and recycled. In addition, a ringer ring 7 is installed between the flush nozzles 8 and 9 to remove moisture and the like remaining on the surface after the flushing.

In the conventional pickling process, the removal of the residual pickling liquid by the double ringer rolls 4 and 5 has a limit in its effect. Because the doublinger rolls 4 and 5 are located inside the pickling section, although they are not immersed in the pickling solution, they are exposed to the acidic atmosphere of the section, so the surface of the roll is wet with the pickling solution. Therefore, even after passing through the pickling section, the pickling liquid remains on the surface of the hot-rolled steel sheet 1, and this residual pickling liquid adversely affects the quality of the steel sheet by generating rust in the washing section. Therefore, a large amount of water is sprayed on the upper and lower portions of the steel sheet drawn into the washing section 3 to wash the bare steel sheet whose scale is removed by pickling.

This washing step will be described in more detail with reference to FIG. The washing process is divided into three to five steps, and the drawing shows a washing section consisting of four steps as an example. In each step, three nozzles are respectively disposed above and below the steel sheet to flush water by spraying water at about 60 ° C. at high pressure. In the method of washing with water, neutral water is supplied from the pure water tank 16 to the fourth washing nozzle 11 installed at the end of the washing section and sprayed onto the steel sheet. This water is collected in the fourth flush tank 15 and supplied to the third flush nozzle 10 as a previous step. In this manner, the water supplied to the third flush nozzle 10 is the third flush 14, the second flush 9, the second flush 13, the first flush 8 and the first flush. It is circulated to the water washing tank 12 and continuously sprayed to the steel plate surface.

According to this washing process, the water collected in the first washing tank 12 closest to the pickling section has the lowest pH value (highest hydrogen ion concentration). Usually, in the washing section of 1 ~ 3 step, the pH value is 1.5 ~ 3 strong acidity. In the section having this pH value, the surface of the steel sheet is corroded by the following chemical reaction.

Fe + 2H ⁺ -> Fe ²⁺ + H ₂

Fe ²⁺ + 4OH ^-- > 2Fe (OH) ₂

2Fe (OH) ₂ + H ₂ O + 1 / 2O _2- > 2Fe (OH) ₃ (corrosion)

When the hot rolled steel sheet is introduced into the washing section with a large amount of residual pickling liquid remaining on the surface thereof, not only the above-mentioned corrosion problem but also the amount of washing liquid used to remove the pickling liquid increases, thereby increasing the burden of the washing liquid. Therefore, development of an apparatus for efficiently removing the pickling liquid remaining on the surface of the pickled steel sheet is required.

The present invention has been proposed in order to meet these demands by installing a nozzle for injecting air at a predetermined position inside the connecting passage connecting the pickling section and the flushing section to inject air at a predetermined spray angle and the injection pressure on the upper and lower surfaces of the steel sheet. The purpose is to provide a device configured to remove pickling liquid remaining on the upper and lower surfaces of the steel sheet.

Residual pickling liquid removing apparatus according to the present invention for achieving the above object, the upper and lower surfaces of the hot-rolled steel sheet in the mouth of the hot-rolled steel sheet is introduced into the connection passage connecting the pickling section and the washing section of the pickling device of the hot rolled steel sheet Air spray nozzles for spraying air having an injection angle of 15 to 45 ° in the pickling section direction based on a line perpendicular to the surface of the hot rolled steel sheet are installed in one or two or more stages, and the hot rolled steel sheet is discharged. An air curtain nozzle is installed on the exit side to inject air perpendicular to the upper and lower surfaces of the hot rolled steel sheet to form an air curtain that prevents water vapor from flowing into the pickling section.

The injection pressure of the air injection nozzle is preferably 1 to 5 atmospheres when the air injection nozzle is installed in one stage, and 0.5 to 2 atmospheres when installed in two or more stages.

Hereinafter, with reference to the accompanying Figure 3 will be described in more detail the configuration of the residual pickling solution removal apparatus according to the present invention.

The pickling process is divided into a pickling section 22 and a washing section 23 through which the hot rolled steel sheet 21 passes, and the pickling section 22 includes a double ringer roll 24 and 25 for removing residual pickling liquid after pickling. It is the same as that of the conventional one that it is provided. The most characteristic technical configuration of the present invention is installed nozzles (27, 28) for injecting air in a predetermined position inside the connecting passage 26 connecting the pickling section 22 and the washing section 23 passes through the pickling section. It effectively removes pickling liquid remaining on the surface of a steel sheet.

First, one or two or more stages of air spray nozzles 27 are installed at an entrance side of the connection passage 26 into which the hot rolled steel sheet 21 is introduced. 3 shows that three stages of air spray nozzles 27a, 27b, and 27c are provided. The air spray nozzles 27 are respectively installed on the upper and lower surfaces of the steel sheet and sprayed at a predetermined spray angle and spray pressure to remove pickling liquid remaining on the surface of the steel sheet.

In order to determine the most preferable injection angle and injection pressure, the inventors conducted the experiment as follows. First, the air is sprayed using only one air spray nozzle 27a on the upper and lower surfaces of the steel sheet, and the hydrogen ion concentration of the first flush tank is used to remove the pickling liquid remaining on the surface of the steel sheet while changing the spray angle and the spray pressure. It was found by measuring. The nozzle was shaped so that a 2mm hole was formed in a straight line at 5cm diameter on a titanium tube with a diameter of 2cm, and the spray angles of the air were -45 °, -30 °, -15 ° (tilt to pickling section), 0 ° (steel plate Vertical), and 15 ° (tilt in the washing section) and the injection pressure was changed to 0.5, 1, 2, 5 atm and the results are shown in Table 1 below.                     

Table 1

Injection pressure (atmospheric pressure) Injection angle (°) PH of the first flush tank Comparison 0.5 -45 × -30 × -15 × 0 × Intake of pickling fume section 15 × Intake of pickling fume section One -45 × -30 △ -15 △ 0 × Intake of pickling fume section 15 × Intake of pickling fume section 2 -45 △ -30 ◎ -15 ◎ 0 △ Intake of pickling fume section -15 △ Intake of pickling fume section 5 -45 ◎ Rust on pickling section -45 ◎ Air curtain used, rust generation × -30 ◎ Rust on pickling section -30 ◎ Air curtain used, rust generation × 0 △ Intake of pickling fume section -15 △ Intake of pickling fume section

(-) Injection angle: Spray in the direction of pickling section, (+) Injection angle: Spray in the direction of flush section

Removal effect of residual pickling liquid: Excellent (◎: 3 or more), Normal (△: 2-3), Poor (×: 2 or less)

As can be seen in Table 1, when the injection angle of the air is directed toward the neutral or flush section (+), pickling fumes in the pickling section flow into the flush section and rust occurs throughout the flush section. In addition, the residual pickling liquid was pushed into the water washing section, resulting in a lower value of the first washing tank. On the other hand, when the spray angle was set in the pickling section direction (-), it showed excellent residual pickling liquid removal effect across the spray pressure of 1 to 5 atm at -30 and -15. When the spray angle was -45 °, the residual pickling liquid removal effect was low because the air sprayed from the nozzle spreads over the surface of the steel sheet. In summary, the spray angle of air is preferably 15 to 45 degrees in the pickling section direction based on a line perpendicular to the surface of the steel sheet.

Next, when the injection pressure of air, when the injection pressure is 0.5 atm, the removal effect of the residual pickling liquid was low regardless of the injection angle. In order to show more than the normal removal effect, the air must be injected at least 1 atm. It can be seen. Above 1 atm, the removal effect is improved as the injection pressure increases, but when the injection pressure exceeds 5 atm, excess air flows into the closed pickling section, increasing the pressure of the entire system, causing the pickling fume to leak out of the system. It became. Based on these results, it is preferable to set the injection pressure to 1 to 5 atmospheres when using a single stage air spray nozzle.

On the other hand, when air is injected in the pickling section at a high injection pressure of 5 atm, water vapor in the flush section is introduced into the pickling section due to the pressure difference according to the fluid velocity, and conversely, corrosion occurs at the position of the doublinger rolls 24 and 25. Occurred. Therefore, in order to prevent such a backward flow phenomenon of the water vapor, an air curtain nozzle 28 provided to spray air on the upper and lower surfaces of the steel sheet is provided to form an air curtain on the exit side from which the steel sheet is discharged in the connection passage 26. The jet of air by the air curtain nozzle 28 is preferably made perpendicular to the surface of the steel sheet. This is because, when air is injected inclined in one direction, the flow of air is deflected in that direction, and the effect as an air curtain is inferior. The air injection pressure of the air curtain nozzle 28 is determined based on the injection pressure of the air injection nozzle 27.                     

On the other hand, as described above, the air spray nozzle 27 according to the present invention may be installed in multiple stages to improve the residual pickling liquid removal effect. At this time, the experiment was carried out as follows to measure the preferred injection pressure according to the number of stages installed. First, the air spray nozzles 27 of 1 to 4 stages are installed, and the air is sprayed at an injection pressure of 0.5, 1, and 2 atmospheres, and an injection angle of -30 °, respectively, and the first pickling tank removes residual pickling liquid. It was measured by the value of. At this time, an air curtain was used to prevent water vapor from entering the pickling section.

[Table 2]

Number of nozzle stages Injection pressure (atmospheric pressure) PH of the first flush tank One 0.5 × One △ 2 ◎ 2 0.5 △ One ◎ 2 ◎ 3 0.5 ◎ One ◎ 2 ◎ 4 0.5 ◎ One ◎ 2 ◎

Spray angle: spray in the direction of pickling section (-30 °)

Removal effect of residual pickling liquid: Excellent (◎: 3 or more), Normal (△: 2-3), Poor (×: 2 or less)

As shown in Table 2, in the case of two or more nozzles, the residual pickling liquid removal effect is more than normal even at a low injection pressure (0.5 atm). This is because the injection section is longer than using the one-stage injection nozzle. If the injection pressure is higher, the removal effect is improved, but in the case of two or more stages, when each injection pressure exceeds 2 atm, excess air flows into the closed pickling section, increasing the pressure of the whole system, and the pickling fume leaks out of the system. The phenomenon occurs. Therefore, when the air injection nozzle is two or more stages, it is preferable that the injection pressure is 0.5-2 atmospheres.

As described above, according to the residual pickling liquid removing apparatus according to the present invention, an acid remaining on the surface of the hot-rolled steel sheet even after passing through the pickling section by an air spray nozzle and an air curtain nozzle provided on the connection passage between the pickling section and the flushing section. The washing liquid can be removed very effectively to prevent corrosion in the washing section, as well as to reduce the amount of washing liquid used.

Claims (3)

The upper and lower surfaces of the hot rolled steel sheet 1 are located inside the connection passage 26 connecting the pickling section 22 and the water washing section 23 among the pickling apparatuses of the hot rolled steel sheet 21. Air spray nozzles 27 for spraying air having an injection angle of 15 to 45 ° in the pickling section 22 direction on the basis of a line perpendicular to the surface of the hot rolled steel sheet 21 to one or two or more stages. It is installed, to inject air vertically on the upper and lower surfaces of the hot-rolled steel sheet 21 to form an air curtain on the outlet side from which the hot-rolled steel sheet 21 is discharged to prevent the water vapor of the water washing section 23 is introduced into the pickling section. Residual pickling liquid removing apparatus, characterized in that the air curtain nozzle 28 is installed. delete The residual pickling liquid removing apparatus according to claim 1, wherein the spray pressure of the air spray nozzle 27 is 1 to 5 atmospheres when installed in one stage, and 0.5 to 2 atmospheres when installed in two or more stages. .

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