JPH10328738A - Method and apparatus for cooling hot rolled coil - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To propose a cooling method for rapidly and uniformly realizing cooling of a hot-rolled coil. SOLUTION: In cooling a hot-rolled coil by spraying a cooling medium onto a side surface of the hot-rolled coil from below, a droplet diameter of water droplets is increased toward a rising flow of hot air rising from the side surface of the hot-rolled coil. Cooling fog in the form of a mist of 50 μm or less is sprayed evenly within a range where the side surface of the hot-rolled coil is covered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for preventing a hot-rolled coil wound on a coil from being wet after hot rolling.
FIELD OF THE INVENTION The present invention relates to a method for fog cooling (to prevent rusting) and an apparatus used for performing the method.

[0002]

2. Description of the Related Art A hot-rolled coil (hereinafter, simply referred to as a "coil") after hot rolling is left on a coil yard of a hot rolling factory or on a floor of a coil warehouse, and the room temperature and coil temperature in the factory or warehouse are reduced. It was cooled over time using the difference from the temperature. However, when the temperature difference between the coil and its surroundings is small and it takes a long time to cool the coil, various technologies for shortening the cooling time by performing cooling using water have been developed.

For example, Japanese Patent Application Laid-Open No. 57-134207 discloses a spray nozzle for suppressing a rise in the temperature of an indoor atmosphere around the ceiling of a coil cooling building to detect indoor temperature and humidity, A method is disclosed in which the amount of water spray is set according to the type of, and the spray amount is automatically controlled by comparing the detected value with the set value.

[0004]

However, the above proposal is a technique for increasing the cooling rate by controlling the indoor atmosphere temperature and humidity, and has a superior cooling effect as compared with air cooling. Since the heat transfer coefficient of the coil was not so large, it was difficult to rapidly cool the coil, and uniform cooling was not possible.

Accordingly, it is a primary object of the present invention to provide a method and an apparatus for rapidly and uniformly cooling a hot-rolled coil without rusting. Another object of the present invention is to
An object of the present invention is to establish a coil cooling technology that provides convenience in handling and storing hot-rolled coils.

[0006]

In order to forcibly cool the coil by blowing cooling water on the coil, the inventors use cooling water in the form of mist, that is, cooling fog, and in particular, use this cooling fog. By optimizing the water droplet diameter, it was found that uniform and rapid cooling was possible without wetting the coil even when spraying onto the coil, that is, without generating rust, and to complete the present invention. It has arrived.

According to the present invention, which has been developed based on the above-mentioned knowledge, the cooling fog joins the cooling fog from below the hot-rolled coil to the surface of the coil side with the upward flow of air rising along the surface of the coil side. A method for cooling a hot rolled coil, characterized in that the coil is cooled by jetting so as to cause the coil to cool. Also, the present invention provides a method of cooling a hot-rolled coil by spraying a cooling medium onto a side surface of the hot-rolled coil from underneath. Is a method of cooling a hot-rolled coil, characterized in that a sprayed cooling fog having a size of 50 μm or less is evenly sprayed within a range where the side surface of the hot-rolled coil is covered.

[0008] In the present invention, it is preferable to inject the spray quantity of cooling fog under the condition of 0.05 Nm ³ / h · coil ~0.5Nm ³ / h · coils. Further, in the present invention, the upward flow of the air containing the cooling fog on the side surface of the coil, the average flow velocity (however, 30 mm from the coil surface
(Measured within) is preferably at least 1 m / s.

Next, the cooling method of the present invention is directed to a cooling device for a coil, wherein at least three cooling fog injection nozzles are provided below the coil and directed to the side surface of the coil. A nozzle cooling device characterized in that the nozzle is disposed so as to be directed to an intermediate portion between the inner peripheral surface and the outer peripheral surface of the hot-rolled coil.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a coil cooling device according to the present invention has an air pipe 3 and a water pipe on both sides of a coil array 2 in which a plurality of coils 1 are arranged. The pipes 4 are arranged in pairs to supply air and water, respectively. As shown in FIGS. 1 and 2, the air pipe 3 and the water pipe 4 are provided with at least three fog injection nozzles directed to the coil 1, and four fog injection nozzles 5 a to 5 d in the illustrated example. Installed on each side of each coil 1
Cooling fog, which is formed by mixing cooling water and air from these nozzles to form a mist, is sprayed toward the coil 1 to cool the coil.

Here, the fog injection nozzles 5a to 5d are
As illustrated in FIGS. 2 and 3, by configuring the opening shape and the elevation angle α with respect to the coil 1 to be different for each nozzle, the opening shape and the relative position between the coil and the fog injection nozzle are determined. The elevation angle α can be set as appropriate. That is, by adjusting the opening shapes and the elevation angles α of the fog injection nozzles 5a to 5d, minute water droplets from each nozzle are developed in a region that evenly covers the coil side surface, as shown in FIG. 3A, for example. be able to. As a result, the amount of rising of the high-temperature air rising from the side surface of the coil 1 increases, and the rising speed of the high-temperature air becomes uniform, so that spraying is realized. Therefore, the coil 1 can be cooled extremely efficiently. is there.

More specifically, the elevation angle α of the spray nozzle is determined by the position of the straight line extending from the center of each nozzle in accordance with the elevation angle and the contact point of the coil (indicated by the black circle in FIG. 4A). (Intermediate part with the outer peripheral surface). However, if the position of the contact satisfies the condition that the rising speed of the air rising along the surface of the coil side is maintained at about 5 m / s, there is no problem even if the position is slightly changed.

In the present invention, at least three injection nozzles are provided on each side of each coil side surface. The reason for this is that if cooling is performed with two or less nozzles, the spray area per nozzle becomes too large, fog penetrates into the inner winding portion of the coil, and the portion is rapidly cooled, wets and oxidizes. That's why. For example, when arranging three spray nozzles, it is effective to arrange them as shown in FIG.

In order to spray the cooling fog in the form of mist from the fog spray nozzle, water introduced from each pipe into the nozzle is used.
(About 1 kg / cm ² ) and compressed air (about 1.5 kg / cm ² ) to spray as small water droplets.

If possible, it is preferable to control the rising flow of the cooling fog-containing high-temperature air at an average flow velocity of 3 to 5 m / s.
As shown in Fig. 7, the relationship between this average flow velocity and the convective heat transfer coefficient of the ascending flow (excluding the cooling contribution of the fog) indicates that when the average flow velocity exceeds 5 m / s, the convective heat transfer coefficient increases. This is because the running cost increases as the effect is saturated and the upward flow velocity increases. 3m / s
It can be said that it is more preferable to control before and after. Also, 1
If it is less than m / s, it is almost the same as the condition of natural cooling without using a fan, so 1 m / s or more is necessary. In addition,
Measurement point of coil surface wind speed is 30mm from coil side surface
The values measured within the range are the values obtained by measuring the eight points in FIG.

Here, it is important to control the water droplet diameter of the cooling water injected from the cooling fog injection nozzle to 50 μm or less. That is, as shown in FIG. 5, as shown by the results of investigating the heat transfer coefficient of the cooling surface in the various cooling methods, it is understood that the cooling by spraying is more efficient than the cooling by forced cooling or the forced cooling by the fan. Furthermore, when the cooling method by spraying was examined in detail, when cooling to 50 ° C. at which the coil can be shipped directly, the cooling efficiency increases as the water droplet diameter increases, but the cooling surface becomes wet, It has been found that when applied to a coil, a problem occurs that induces oxidation of the coil. That is, when cooling by spraying, rapid cooling is achieved without oxidizing the coil by setting the water droplet diameter to 50 μm or less. Preferably, the cooling fog used in the present invention has a water droplet diameter of 30 μm or less.

The reason why the cooling completion temperature is set to 50 ° C. is as follows.
This is because the maximum temperature at which direct shipment is possible, for example, the maximum temperature at which surface defects do not occur in a skin pass performed by unwinding a coil.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The coil cooling device shown in FIGS.
Coil with a coil width of 1200mm and a coil diameter of 2000mm
Are arranged in a row as shown in FIG.
Water pipe 3 and air pipe 4 installed on each side
Water and outside air (average temperature: 35 ° C)
And placed at the shortest distance of 300mm from the coil
From the spray nozzles 5a to 5d obtained,
Micro water droplets having a diameter of 30 μm were jetted. At this time,
The amount of water and air supplied to the squid
25 l / h x 4 pieces (1.0 kg / cm^Two) And 5 Nm^Three/ H ×
4 pieces (1.5 kg / cm ^Two)Met. Also, each nozzle is
The tip is placed 300 mm away from the coil, and 5a and 5
The elevation angle α of b is 60 ° and the elevation angles α of 5c and 5d are
It was set to 80 °.

Under the above conditions, the time required for cooling each coil at the maximum temperature portion of 50 ° C. or less was examined. As a result, all the coils were completed within 3 days. Incidentally, when the same coil was cooled by conventional standing cooling, it took 5 to 6 days.

[0020]

According to the present invention, uniform rapid cooling of the coil can be realized at low cost, and it is not necessary to store the coil in a warehouse or the like for a long time, so that the coil can be shipped directly. Yes, and the cost of logistics is significantly reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cooling device of the present invention.

FIG. 2 is a side view showing a cooling device of the present invention.

FIG. 3 is a schematic diagram illustrating blowing of cooling fog from an injection nozzle.

FIG. 4 is an explanatory diagram of a measurement point of an upward air flow and a nozzle elevation angle.

FIG. 5 is a graph showing heat transfer coefficients of a cooling surface in various cooling systems.

FIG. 6 is a graph showing a relationship between a coil surface wind speed and a convective heat transfer coefficient.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil 2 Coil row 3 Water pipe 4 Air pipe 5a-5d Spray nozzle

Claims (5)

[Claims] 1. A cooling fog is injected from below a hot-rolled coil toward a side surface of the coil so as to join an upward flow of air rising along the surface of the coil side. A method for cooling a hot-rolled coil, comprising: cooling a hot-rolled coil. 2. When cooling the hot-rolled coil by spraying a cooling medium onto the side surface of the hot-rolled coil from below, the droplet diameter is adjusted toward the rising flow of hot air rising from the side surface of the hot-rolled coil. A method for cooling a hot-rolled coil, characterized in that a sprayed cooling fog having a particle size of 50 μm or less is uniformly sprayed within a range where the side surface of the hot-rolled coil is covered. 3. The method according to claim 1, wherein the amount of water sprayed from the cooling fog is from 0.05 Nm ³ / h · coil to 0.
A cooling method characterized by injecting under conditions of 5 Nm ³ / h coil. 4. An ascending flow of hot air containing cooling fog on a side surface of the coil, wherein an average flow velocity (measured within 30 mm from the coil surface) is at least 1 m / m.
The cooling method according to any one of claims 1 to 3, wherein s is set. 5. A cooling device for a hot-rolled coil, comprising at least three cooling fog injection nozzles directed to the side of the coil below the hot-rolled coil, wherein the fog injection nozzle comprises a hot-rolled coil. A cooling device for a hot-rolled coil, wherein an intermediate portion between an inner peripheral surface and an outer peripheral surface of the coil is oriented.