JP2970509B2 - Method and apparatus for removing cooling water from steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing cooling water on a steel strip such as stagnant water on a steel sheet generated by hot run cooling of a continuous hot strip rolling line.

[0002]

2. Description of the Related Art In a cooling process of a hot-rolled steel strip in a hot rolling line, hot run cooling is performed by injecting pressurized water from a spray nozzle, a laminar flow nozzle, a jet nozzle or the like onto the upper and lower surfaces of the hot-rolled steel strip. . In hot run cooling, a steel strip running at high speed must be cooled in a limited space and time, and the cooling end temperature must be controlled in a severe range. The cooling water sprayed on the upper surface of the hot steel strip by hot run cooling flows on the steel strip surface in the width direction or the traveling direction of the steel strip after colliding with the steel strip, and falls downward from the end face of the steel strip.

[0003] Therefore, at the cooling device entrance side, the cooling water that stays or flows on the upper surface of the steel strip flows out upstream from the cooling start position, the temperature of the steel strip at the cooling start position decreases, and the steel strip at the cooling start position becomes lower. The strip temperature becomes non-uniform, causing uneven cooling or distortion of the steel strip due to this, resulting in poor flatness.
In addition, at the cooling device outlet side, similarly, the cooling water remaining on the upper surface of the steel strip flows downstream from the cooling end position, so that the steel strip is cooled more than necessary, and water cooling is performed due to deterioration in accuracy of the winding temperature and uneven cooling. This causes problems such as deformation of the steel strip.

As a countermeasure for the cooling water staying on the upper surface of the steel strip, a draining nozzle for removing the cooling water remaining on the upper surface of the steel strip is installed on the upper surface of the steel strip, and a high-pressure fluid jetted from the draining nozzle is used. Although the remaining cooling water is removed, a normal one-fluid draining nozzle cannot remove the cooling water remaining on the upper surface of the steel strip because the energy value is low, and the side guide installed on the opposite side of the draining nozzle There was a lot of water that bounced off after colliding with water, and the water that bounced back after draining again dropped on the upper surface of the steel strip, causing a variation in the temperature in the width direction of the steel strip, resulting in a decrease in accuracy of the winding temperature and a deterioration in flatness.

[0005] Another method is to remove the cooling water staying on the upper surface of the hot steel strip by suctioning the cooling water by a negative pressure at an inlet end and / or an outlet end of a water cooling device. A method has been proposed in which the suctioned cooling water is forcibly discharged to the outside of the line by a pump (Japanese Patent Application Laid-Open No. Sho 59-30415).

[0006]

If only the cooling water remaining on the upper surface of the steel strip is removed, it is effective to increase the water amount and water pressure of the draining nozzle. It is necessary to improve the supply capacity of
Equipment costs are high. In addition, when the water amount or the water pressure of the draining nozzle is increased, the amount of water that collides with the side guide and rebounds increases, and the amount of residual water after draining increases, so that stable cooling cannot be performed. Injection of compressed air only is effective when the amount of cooling water is small, but in hot run cooling, accumulated cooling water flows over the steel strip at a flow rate of 100 l / min or more. Has the disadvantage of being bad.

Further, the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Sho 59-30415 is designed to drain water by sucking cooling water staying on the upper surface of the steel strip by negative pressure, and it is difficult to drain a large amount of staying cooling water. In addition, the suction nozzle and the steel strip may come into contact with each other due to the flapping of the steel strip running at high speed, and it is impossible to carry out the operation in actual operation.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art, improve the drainage of cooling water staying on the upper surface of a steel strip, and remove cooling water that rebounds by colliding with a side guide. An object of the present invention is to provide a method and an apparatus for removing water.

[0009]

Means for Solving the Problems The present inventor quantitatively grasped the residual water after draining by the draining nozzle in order to achieve the above object, and examined the application to an actual machine. By using a mixing nozzle that can mix and jet high-pressure water, the collision energy with the cooling water staying on the top of the steel strip is increased, and the drainage is improved. It was clarified that the bounce water was reduced because of the small size, and that the bounce water could be forcibly removed by providing an inclined slit in the side guide where the angle of contact of the mixed fluid from the drain nozzle exceeded 90 °. The invention has been reached.

[0010] That is, the invention of claim 1, when Hottoran cooling of the hot sheet continuous rolling line, water quantity and air
This is a method of removing cooling water on a steel strip, wherein the cooling water is mixed at a ratio of 1: 5 to 1:15 and jetted from a drain nozzle to remove cooling water remaining on the steel strip.

[0011] Also, the invention is present as claimed in claim 2, the steel for removing cooling water staying on the steel strip when Hottoran cooling of the hot sheet continuous rolling line, by draining nozzle is disposed on the side top of the steel strip In the strip cooling water removing device, the side guide installed on the opposite side of the draining nozzle is provided with an inclined slit in which the angle of contact of the fluid from the draining nozzle exceeds 90 °. The removal device.

Further , the invention of claim 3 of the present application is directed to a steel strip for removing cooling water staying on a steel strip during hot run cooling of a continuous hot strip rolling line by a draining nozzle arranged on a side upper surface of the steel strip. In the upper cooling water removal device, a mixing nozzle in which the ratio of the amount of water and the amount of air is mixed at a ratio of 1: 5 to 1:15 as the draining nozzle, and a side guide installed on the opposite side of the mixing nozzle, This is a device for removing cooling water on a steel strip, wherein an inclined slit in which the contact angle of the mixed fluid from the drainer spray nozzle exceeds 90 ° is provided.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic perspective view of a device for removing cooling water on a steel strip of the present invention, FIG. 2 is a schematic plan view thereof,
FIG. 3 is a cross-sectional view of the portion where the side guide is provided with the inclined slit, FIG. 4 is a cross-sectional view of the portion where the side guide is provided with the inclined slit, and FIG. 5 is a perspective view of the portion where the side guide is provided with the inclined slit. FIG.

In FIGS. 1 and 2, 1 is a steel strip running at a high speed in the direction of the arrow, and 2 is a cooling water header provided above the steel strip 1 for hot run cooling. The steel strip 1 is cooled to a predetermined temperature by flowing down the water 3. Numeral 4 is a draining nozzle composed of a nozzle for mixing air and water disposed on the side upper surface of the steel strip 1 on the outlet side of the cooling zone, at a predetermined angle, for example, above the steel strip 1 side, preferably in the traveling direction of the steel strip 1. Air and water mixed fluid on steel strip 1 at 0 to ± 10 ° to the direction perpendicular to
5 is sprayed at a predetermined spray angle, for example, 25 to 40 °, and the retained water 6 on the steel strip 1 is blown off to the side opposite to the draining spray nozzle 4 to be removed.

The draining nozzle 4 composed of a nozzle for mixing air and water used in the present invention increases the collision energy by mixing air into the high-pressure water, as compared with a conventional draining nozzle that injects only high-pressure water, Drainability can be improved. However, simply mixing air into water does not improve drainage. That is, when the amount of air or the air pressure is small, no air is mixed into the water, and there is no change in comparison with a conventional draining nozzle that injects only high-pressure water. On the other hand, when the air amount or air pressure is too high, the energy becomes too large, the particle size of the water in the sprayed mixed fluid 5 becomes small, and the water becomes mist-like due to collision with the atmosphere, and the drainage property becomes poor. No longer available.
When the amount of air is small, water flows backward to the air pipe and is not mixed.

Therefore, the use range of the air of the draining nozzle 4 is determined, but the absolute value of the use range varies depending on the amount of water. According to experiments, if the amount of water (m ³ / hr): the amount of air (m ³ / hr) = Vw: Va = 1: 5 to 1:15, the drainage of the mixed fluid 5 is good. It has been confirmed that it is suitable for removing the stagnant water 6 on the steel strip 1. That is, if Vw: Va = 1: less than 5, water and air are not mixed and V
When w: Va = 1: 5 to 1:15, the drainage of the stagnant water 6 on the steel strip 1 is good, and when Vw: Va = 1: 15 or more, it becomes mist-like and the drainage cannot be obtained.

These are related to the speed of the mixed fluid 5 ejected from the draining nozzle 4, and the speed of the mixed fluid 5 ejected from the draining nozzle 4 is determined by the amount of water: Ww (kg / hr), the amount of air: Wa (kg / hr), weight ratio: water = Ww / (Ww + Wa), air = Wa / (W
w + Wa), water density: ρ _w (kg / m ³ ), air density: ρ _a (kg / m
m ³ ) and the nozzle opening area: S (m ² ), the following equation (1) is obtained.

[0018]

(Equation 1)

[0019] Therefore, when the current experimental conditions is introduced into the equation _{(1), Ww = Vw × ρ w,} Wa = Va × ρ a = 5~15Vw × flow rate under the condition of ρa = 1 / 3600S × {Vw + ( 5-15) Vw}.

That is, the flow velocity is 6 to 16 times higher than that of water alone by mixing a little air, and the energy at the time of collision with the stagnant water 6 on the steel strip 1 is 6 ^{2 to} 16 ² As a result, the ability to remove the retained water 6 is improved.

In FIG. 3 to FIG. 5, reference numeral 11 denotes a side guide provided along the opposite side of the draining nozzle 4 to drop the cooling water 3 from the cooling water header 2 downward. 12 is a part of the side guide 11 on the opposite side of the draining nozzle 4
In the inclined slit modified so that the contact angle α of the mixed fluid 5 exceeds 90 °, the retained water 6 on the steel strip 1 blown off in the injection direction by the mixed fluid 5 flows out along the inclined slit 12, Prevent it from bouncing on obi 1. 13 is a guide plate provided above the inclined slit 12,
The mixed fluid 5 which collides with and bounces upward is dropped downward.

With the above-described configuration, the steel strip
The retained water 6 on 1 is blown off by the mixed fluid 5 of air and water injected from the draining nozzle 4, and the inclined slit 1
Flows out along 2 and falls down. Further, the mixed fluid 5 colliding with the inclined slit 12 and bouncing upwards is
Is dropped downward. Therefore, the mixed fluid
5 and the retained water 6 do not rebound after colliding with the side guide 11 and ride on the steel strip 1, which can prevent the temperature of the steel strip 1 from dropping and the occurrence of temperature unevenness. Deterioration of flatness can be prevented.

In the above description, the inclined slit
Although the case where the mixed fluid 5 and the stagnant water 6 splashed by the guide plate 13 provided above 12 are forcibly dropped has been described, if a mechanism for sucking from between the inclined slit 12 and the guide plate 13 is provided, the inclined The mixed fluid 5 and the stagnant water 6 colliding with the slit 12 and jumping upward can be more effectively removed. In addition, the method of the present invention can be applied not only to a hot thin-sheet continuous rolling line, but also to a cooling line of a hot rolling line, drainage of roll cooling water, and removal of water remaining on a steel sheet generated by a descaling device. .

[0024]

Example 1 A steel plate having a width of 1200 mm, a length of 5,000 mm and a thickness of 5 mm was fixed horizontally, and 500 l / min and a flow rate of 5.8 m / s were applied from one end in the longitudinal direction onto the steel plate.
Water is sprayed in the entire width direction toward the other end with ec, 50 water tanks divided into 25 mm width are arranged in the width direction at the lower end of the other end in the width direction, and 600 mm from the center in the width direction of the steel plate at a position 500 mm above the steel plate Drain nozzle with a spray angle of 40 ° at a distance of 90 ° with the steel plate longitudinal direction
High pressure water 80 at a pressure of 6 kg / cm ² · G over the entire width direction of the steel plate.
l / min and a pressure of 3 kg / cm ²・ G 800 Nl / min of high-pressure air (water-to-air ratio = 1:10) are mixed and injected to drain the accumulated water on the steel plate and drain in the width direction of the steel plate. The remaining water in each of the water tanks was quantitatively measured. As a result, a small amount of residual water was found about 900 mm or more from the steel plate edge in the installation direction of the drain nozzle. For comparison, 80 l / min of high-pressure water was injected from a drain nozzle to drain the retained water on the steel plate, and the remaining water in each water tank after draining in the width direction of the steel plate was quantitatively measured. As a result, residual water was generated from about 600 mm from the edge of the steel plate in the installation direction of the drainer spray nozzle.

Example 2 A draining nozzle A having an injection angle of 40 ° was disposed at a position 500 mm above the steel strip on the exit side of the hot-run cooling equipment of the hot strip rolling line and at a distance of 600 mm from the center of the steel strip. Nozzles A to 30
The distance from the center of the steel strip is 1150 500 mm above the steel strip on the downstream side of 0 mm.
A draining nozzle B with a spray angle of 25 ° is disposed at a position of 90 mm with the steel strip traveling direction at an angle of 90 °, and the contact angle of the mixed fluid from the draining nozzles A and B on the side opposite to the draining nozzles A and B. α is set to 100 ° inclined slits, and high pressure water 80l / mi with a pressure of 6kg / cm ²・ G from each draining nozzle A, B
A mixture of n and 800 Nl / min of high-pressure air with a pressure of 3 kg / cm ² · G (water-to-air ratio = 1:10) was mixed and injected, and the water retained in the hot-run cooled steel strip was drained. As a result, there was no water remaining on the steel strip over the entire width direction, and it was possible to completely prevent water that rebounds and falls onto the steel strip. As a result, the winding temperature could be controlled to ± 15 ° C or less with respect to the winding target temperature.

[0026]

As described above, according to the present invention,
By draining water using a drain nozzle that mixes and injects water and air, drainage of accumulated water on the steel strip can be almost completely drained, and water that collides with the side guide and bounces off due to the inclined slits. It is possible to prevent the temperature of the steel strip from lowering and the occurrence of temperature unevenness, and also to prevent the accuracy of the winding temperature from deteriorating and the flatness from deteriorating.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an apparatus for removing cooling water above a steel strip according to the present invention.

FIG. 2 is a schematic plan view of an apparatus for removing cooling water on a steel strip according to the present invention.

FIG. 3 is a cross-sectional view from above of a portion where an inclined slit is provided in a side guide.

FIG. 4 is a cross-sectional view of a portion where an inclined slit is provided in a side guide.

FIG. 5 is a perspective view of a portion where an inclined slit is provided in a side guide.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steel strip 2 Cooling water header 3 Cooling water 4 Drain nozzle 5 Mixed fluid 6 Retained water 11 Side guide 12 Slant slit 13 Guide plate

Claims (3)

(57) [Claims] 1. A cooling water which is mixed at a ratio of water amount to air amount of 1: 5 to 1:15 at the time of hot run cooling in a continuous hot strip rolling line, is injected from a drain nozzle, and stays on a steel strip. method of removing the strip on the cooling water you and removing the. 2. An apparatus for removing cooling water on a steel strip, wherein cooling water staying on the steel strip during hot run cooling of a hot strip continuous rolling line is removed by a draining nozzle disposed on an upper side of the steel strip. The angle of contact of the fluid from the drain nozzle is 90 ° with the side guide installed on the opposite side of the drain nozzle.
An apparatus for removing cooling water above a steel strip, wherein an inclined slit exceeding the number of slits is provided. 3. An apparatus for removing cooling water on a steel strip, wherein cooling water staying on the steel strip during hot run cooling of a continuous hot strip rolling line is removed by a draining nozzle disposed on a side upper surface of the steel strip. As the draining nozzle, a mixing nozzle in which the ratio of the amount of water to the amount of air is mixed at a ratio of 1: 5 to 1:15 is used, and the side guide installed on the opposite side of the mixing nozzle hits the mixed fluid from the draining spray nozzle. An apparatus for removing cooling water on a steel strip, wherein an inclined slit having an angle exceeding 90 ° is provided.