JP6904370B2 - Gas jet cooling device and cooling method - Google Patents

Description

The present invention relates to a gas jet cooling device and a cooling method, and more particularly to a gas jet cooling device and a cooling method used in a steel strip cooling process in a steel strip cold spreading / surface treatment facility.

Cold rolling and surface treatment plants for steel always have a cooling process after the heating process when performing various treatments for steel strips. For example, a continuous annealing furnace is provided with a step of continuously heating, soaking and cooling the steel strip and, if necessary, overaging. In order to obtain the desired characteristics of the steel strip, it is important to cool the steel strip uniformly and rapidly in addition to the heating temperature and soaking time. In recent years, the development of high-tensile steel such as materials for automobiles has progressed, and in order to realize desired tensile strength, bending characteristics, elongation characteristics, etc., the steel strip is rapidly cooled from an annealing temperature of 900 to 800 ° C to a temperature of about 300 to 150 ° C. Process development has been carried out, and more uniform and rapid cooling of steel strips is desired. Further, in the laminating material in which the surface of the steel strip is coated with the resin, it is desired that the steel strip is heated to several hundred degrees Celsius, the resin coating is applied, and then the steel strip is uniformly cooled to less than 100 ° C.

Here, various refrigerants are used as the refrigerant used for cooling the steel strip. When water is used as the refrigerant, a high cooling rate can be obtained and cooling up to the ultra-quenching region is possible, but the biggest drawback is that the shape of the steel strip changes due to quenching strain. There is also a method of cooling the roll by passing water or other refrigerant inside the roll and bringing a steel strip into contact with the surface of the cooled roll to cool the roll, but when the roll comes into contact with the cooling roll, it is locally non-contacted. There is a portion where the steel strip is cooled in the width direction, and the cooling tends to be uneven.
Further, as another cooling means, a cooling method using gas as a refrigerant has been put into practical use. This method has a slower cooling rate than the above-mentioned water cooling or roll cooling, but can relatively uniformly cool the steel strip in the width direction. Therefore, as a cooling means for the steel strip, a cooling method using a gas as a refrigerant is most commonly adopted.

A gas jet cooling device that realizes this gas cooling generally includes a nozzle header formed in a tubular shape extending in the longitudinal direction and arranged on both sides or one side of a steel strip. The nozzle header is installed so that its longitudinal direction is the width direction of the steel strip, and has a gas injection port on the side facing the steel strip.
However, in this gas cooling, the cooling rate for the steel strip is slower than that for cooling with other refrigerants, so in order to increase the cooling rate as much as possible, a large flow rate of gas is introduced into the tubular nozzle header, and this gas is gasmed. It is necessary to inject from the injection port toward the steel strip at high speed. At that time, a large amount of pressure loss occurs in the nozzle header, and a static pressure deviation inside the nozzle header occurs, so that the gas ejection amount and the gas ejection speed become non-uniform in the longitudinal direction of the nozzle heddle, and the steel strip is accompanied by this. The cooling temperature deviation in the width direction also tends to increase.

Therefore, various studies have been conventionally made on methods for improving the non-uniformity of the gas ejection amount and the gas ejection speed in the longitudinal direction of the nozzle header in the gas jet cooling device.
Conventionally, for example, those shown in Patent Document 1 are known as those for improving the non-uniformity of the gas ejection amount and the gas ejection speed in the longitudinal direction of the nozzle header.
In the gas jet cooling device of the continuous annealing furnace shown in Patent Document 1, a plurality of tubular nozzle headers extending in the steel strip width direction and having a length longer than the steel strip width are arranged in the steel strip traveling direction. A plurality of gas injection ports are arranged at equal pitches in the steel strip width direction on the steel strip facing side of the nozzle header. The distance L from the steel strip to the surface of the nozzle header, the hole diameter D of the gas injection port, and the pitch Pw in the width direction of the steel strip of the gas injection port are L in the range of 50 to 120 mm and 3 ≦ L /. The relationship of D7 and 2.5 ≦ Pw / D ≦ 9 is satisfied, and further, the hole diameter D of the gas injection port and the pitch P1 in the steel strip traveling direction of the nozzle header satisfy the relationship of 2.5 ≦ P1 / D ≦ 9. ..
According to the gas jet cooling device of the continuous annealing furnace shown in Patent Document 1, even if the gas ejection speed from the nozzle is increased in order to obtain a high cooling speed, the nozzle cooling is performed by promoting the gas circulation in the cooling zone. It can maximize its capacity and achieve high efficiency cooling.

Further, as a material for uniformly cooling a steel sheet, for example, the one shown in Patent Document 2 is also known.
The steel plate mist cooling device shown in Patent Document 2 includes a mist pipe having a double pipe structure including a cooling water pipe and an air pipe containing the cooling water pipe. The cooling water pipe has a plurality of cooling water outlet holes in the longitudinal direction thereof, and the air pipe has an air outlet hole at a position in the same longitudinal direction as the cooling water outlet hole. Further, one end in the longitudinal direction of the air pipe is an open open end, the other end in the longitudinal direction of the air pipe is a closed closed end, and the air supplied from the open end is the air pipe. It flows in one direction toward the closed end. The air pipes arranged side by side in the longitudinal direction of the steel sheet have staggered closing ends, and the directions of air flowing in one direction in the air pipes are staggered.
According to the steel sheet mist cooling device shown in Patent Document 2, when a mist-like mist is sprayed on a traveling steel sheet to cool the steel sheet, the steel sheet can be cooled uniformly.

Further, as a material capable of ejecting the raw material gas uniformly and at high speed, conventionally, for example, the one shown in Patent Document 3 is known.
The nozzle for supplying the raw material gas for the chemical vapor deposition treatment shown in Patent Document 3 is a nozzle for blowing the raw material gas toward the metal strip continuously introduced in the vertical treatment for the chemical vapor deposition. Then, a discharge port for the raw material gas is formed in a slit shape on a bus having a shaft length over at least the entire width of the metal strip, and is radially separated from the discharge port on the back side and the axial end of the pipe body. An inlet for raw material gas will be provided in the section. Further, a partition plate that divides the internal space of the pipe body into two parts, the discharge port side and the back side, is arranged between the partition plate and the peripheral surface of the pipe body through a gap, and the above-mentioned raw material gas is placed in the back side section. There is an introduction port for.
According to the nozzle for supplying the raw material gas of the chemical vapor deposition treatment shown in Patent Document 3, the raw material gas can be ejected uniformly and at high speed, which is effective when it is desired to form a homogeneous film by the chemical vapor deposition treatment. Can be.

Japanese Patent No. 5326626 Japanese Patent No. 6176204 Japanese Patent No. 4549081

However, the gas jet cooling device of the continuous annealing furnace shown in Patent Document 1, the mist cooling device of the steel plate shown in Patent Document 2, and the nozzle for supplying the raw material gas for the chemical vapor deposition treatment shown in Patent Document 3 are as follows. There was a problem.
That is, in the case of the gas jet cooling device of the continuous annealing furnace shown in Patent Document 1, in order to make the gas ejection speed of the nozzle header alone in the steel strip width direction uniform, from both sides of the tubular nozzle header in the steel strip width direction. Gas is being injected. In this case, when the gas jet cooling device is installed in a narrow place, especially in a place where gas can be injected only from one side in the steel strip width direction of the nozzle header, gas is injected from both sides in the steel strip width direction of the nozzle header. There is a problem that the gas flow velocity injected from the nozzle header cannot be made uniform in the steel strip width direction, and the cooling temperature deviation in the steel strip width direction increases accordingly.

Further, in the case of the steel plate mist cooling device shown in Patent Document 2, one end in the longitudinal direction of the air pipe is an open open end, and the other end in the longitudinal direction of the air pipe is a closed closed end. The air supplied from the open end flows in one direction toward the closed end in the air pipe. However, the air pipes arranged side by side in the longitudinal direction of the steel sheet have staggered closing ends, and the directions of air flowing in one direction in the air pipes are staggered. For this reason, it is necessary to install air supply sources for the air pipes on both sides of the steel plate along the longitudinal direction of the steel plate, and the closed ends of the air pipes arranged side by side in the longitudinal direction of the steel plate face in the same direction. When the gas jet cooling device is installed in a place where gas can be injected from only one side in the longitudinal direction of the air pipe, the gas flow velocity injected from the air pipe cannot be made uniform in the longitudinal direction.

Further, also in the case of the raw material gas supply nozzle of the chemical vapor deposition treatment shown in Patent Document 3, the raw material gas is input from both sides in the metal strip width direction of the raw material gas supply nozzle, and the raw material gas supply nozzle When the raw material gas supply nozzle is installed in a place where the raw material gas can be input from only one side in the metal strip width direction, the gas flow velocity injected from the raw material gas supply nozzle should be made uniform in the metal strip width direction. I couldn't.

Therefore, the present invention has been made to solve this conventional problem, and an object of the present invention is that the nozzle header can be installed only in a narrow place where cooling gas can be injected from only one side in the longitudinal direction. Even so, it is an object of the present invention to provide a gas jet cooling device and a cooling method capable of making the flow velocity of the cooling gas injected from the nozzle header uniform in the longitudinal direction of the nozzle header.

In order to achieve the above object, the gas jet cooling device according to one aspect of the present invention includes a nozzle header extending in the longitudinal direction and having a gas injection port on the side facing the object to be cooled, and the length of the nozzle header. One end in the direction is an open open end, and the other end in the longitudinal direction of the nozzle header is a closed closed end, which is supplied from the open end to the inside of the nozzle header. The cooling gas flows in one direction toward the closed end, and is an opening formed on the back side of the nozzle header with respect to the gas injection port and on one side in the longitudinal direction of the nozzle header. The gist is that a pressure equalizing pipe is provided to connect the portion and the opening formed on the other side.

Further, the gas jet cooling method according to another aspect of the present invention is intended to cool an object to be cooled by using the gas jet cooling device described above.

According to the gas jet cooling device and the cooling method according to the present invention, the gas is injected from the nozzle header even when it can be installed only in a narrow place where the cooling gas can be input only from one side in the longitudinal direction of the nozzle header. It is possible to provide a gas jet cooling device capable of making the flow velocity of the cooling gas uniform in the longitudinal direction of the nozzle header.

It is a perspective view of the gas jet cooling apparatus which concerns on one Embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line XX in FIG. It is a schematic diagram which shows the schematic structure of the 1st stage surface side nozzle header used in the gas jet cooling apparatus shown in FIG. It is a schematic diagram which shows the schematic structure of the 1st stage surface side nozzle header used in the gas jet cooling device which concerns on a reference example. The flow velocity ratio of the cooling gas injected from the surface side nozzle header of the gas jet cooling device according to the embodiment in the steel strip width direction and the cooling gas injected from the surface side nozzle header of the gas jet cooling device according to the comparative example. It is a graph which shows in comparison with the flow velocity ratio in the steel strip width direction of.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention, and the technical idea of the present invention describes the material, shape, structure, arrangement, etc. of the components. It is not specified in the following embodiments.
The drawings are schematic. Therefore, it should be noted that the relationship, ratio, etc. between the thickness and the plane dimension are different from the actual ones, and there are parts where the relationship and ratio of the dimensions are different between the drawings.

FIG. 1 is a perspective view of a gas jet cooling device according to an embodiment of the present invention.
The gas jet cooling device 1 shown in FIG. 1 is applied to an in-line coater (resin film coating device) in a continuous annealing facility, and a steel strip S heated to several hundred degrees Celsius and coated with a resin film is cooled to less than 100 ° C. It cools.
The gas jet cooling device 1 includes a cooling gas introduction duct 10 arranged on one side in the width direction of the steel strip S as a cooling object traveling downward via the roll 17. Cooling gas (air in this embodiment) is supplied to the cooling gas introduction duct 10 from a cooling gas supply source (not shown).

The cooling gas introduction duct 10 has a plurality of stages (9 stages in the present embodiment) of surface side nozzles arranged at a predetermined pitch along the traveling direction of the steel strip S on the surface Sa side of the steel strip S. header ₁₁ 1 to 11 _9, a plurality of stages (this being arranged at a predetermined pitch so as to form the traveling direction in pairs with the surface-side nozzle headers ₁₁ 1 to 11 ₉ along the steel strip S on the back Sb side of the steel strip S in the embodiment and the back-side nozzle headers 12 ₁ to 12 ₉ of 9 stages) are connected.
Here, since the configuration and shape of the surface-side nozzle headers ₁₁ 1 to 11 ₉ and the back surface-side nozzle headers ₁₂ 1 to 12 ₉ are the same, thereafter, the first stage of the surface-side nozzle headers 11 ₁ Only configurations and shapes Will be described, and the description of other nozzle header configurations and shapes will be omitted.

As shown in FIGS. 1 and 3, the front surface side nozzle header 11 ₁ is formed in a cylindrical shape extending in the longitudinal direction. The front surface side nozzle header 11 ₁ is installed so that its longitudinal direction is the width direction of the steel strip S, and its length is longer than the width of the steel strip S. Then, the on opposite side steel strip S surface side nozzle headers 11 _1, as shown in FIGS. 2 and 3, the gas injection port 13 is formed. The gas injection port 13 is formed in a rectangular slit elongated in the longitudinal direction of the surface-side nozzle headers 11 _1.
The surface-side nozzle headers 11 ₁ in the longitudinal direction of one side of the end portion 11a, i.e., the end portion 11a of the side connected to the cooling gas inlet duct 10 has a opened open end. On the other hand, the surface-side nozzle headers 11 ₁ in the longitudinal direction of the other side end portion 11b, i.e. the end portion 11b of the side connected to the cooling gas inlet duct 10 opposite to by closure member 14 as shown in FIG. 3 It is closed and is a closed end.

On the surface side nozzle headers 11 ₁ open end, the cooling gas supplied to the cooling gas inlet duct 10 is introduced, cooling gas introduced into the surface side nozzle headers 11 ₁ from the open end Flows in one direction toward the closed end. Then, the cooling gas is injected from the gas injection port 13 to the surface Sa side of the steel strip S.
Further, as shown in FIG. 3, a pair of rectangular openings 15 are provided on the back side of the front surface side nozzle header 11 ₁ with respect to the gas injection port 13 and on the open end side and the closed end side in the longitudinal direction. It is formed. Each opening 15 is formed between external and internal surface side nozzle headers 11 ₁ in the through hole so as to communicate. As shown in FIG. 3, each of the opening 15 formed on the open end side and the opening 15 formed on the closed end side of the front surface side nozzle header 11 _{1 is one end portion in the width direction of the steel strip S.} And is arranged outside in the width direction from each of the other side ends.

Then, the pair of openings 15 are connected to each other by a pressure equalizing pipe 16. By a pair of openings 15 with each other it is connected by a pressure equalizing pipe 16, the longitudinal pressure of the inner surface-side nozzle headers 11 ₁ becomes uniform. In the pressure equalizing pipe 16, each of the opening 15 formed on the open end side and the opening 15 formed on the closed end side of _{the surface side nozzle header 11 1 is one side end portion in the width direction of the steel strip S and the other side.} Since it is arranged outside each of the side ends in the width direction, it is longer than the width size of the steel strip S.

The pressure equalizing pipe 16 includes a pressure equalizing pipe main body 16a having the same cross-sectional shape along the longitudinal direction and a pair of lids 16b that close both ends of the pressure equalizing pipe main body 16a in the longitudinal direction. Equalizing pipe body 16a is fixed by welding to the outer peripheral surface of the surface-side nozzle headers 11 _1. Each lid 16b is welded to the end surface of the outer peripheral surface and equalizing pipe body 16a of the surface-side nozzle headers 11 _1. Then, the cross-sectional area perpendicular to the longitudinal direction of the pressure equalizing pipe 16, i.e. pressure equalizing pipe body 16a is set to be more than 5% of the cross-sectional area perpendicular to the longitudinal direction of the surface-side nozzle headers 11 _1. Equalizing pipe when the cross-sectional area perpendicular to the longitudinal direction of the main body 16a is less than 5% of the cross-sectional area perpendicular to the longitudinal direction of the surface-side nozzle headers 11 _1, equalizing pipe body 16a surface-side nozzle headers sectional area is too small for It _{is difficult for the pressure inside the 11 1} in the longitudinal direction to become uniform.

The steel strip S travels downward via the roll 17 with respect to the gas jet cooling device 1 configured in this way. At that time, the cooling gas is introduced from the cooling gas inlet duct 10 to the open end of each surface-side nozzle headers 11 ₁ to 11 ₉ and the back surface-side nozzle headers 12 ₁ to 12 _9, the surface-side nozzle headers from the respective open end 11 ₁ to 11 ₉ and the cooling gas introduced into the back-side nozzle headers ₁₂ 1 to 12 ₉ flows in one direction toward the closed end. Then, the cooling gas is injected from the surface side nozzle headers ₁₁ 1 to 11 ₉ and the back surface-side nozzle headers ₁₂ 1 to 12 ₉ of the gas injection port 13 to the surface Sa side and back Sb side of the steel strip S. As a result, the front surface Sa and the back surface Sb of the steel strip S are cooled.

In this case, each surface-side nozzle headers ₁₁ 1 to 11 ₉ and the surface-side nozzle headers ₁₁ a rear side of the back surface-side nozzle headers ₁₂ 1 to 12 ₉ of the gas injection ports 13 1 to 11 ₉ and the rear surface side It is connected by a nozzle header 12 ₁ to 12 ₉ in the longitudinal direction of the open end opening formed in the side 15 and a closed end opening formed in the side 15 Hitoshi Toga pipe 16. Therefore, internal longitudinal pressure has become uniform, the surface-side nozzle headers ₁₁ 1 to 11 ₉ and the back surface side of each surface-side nozzle headers ₁₁ 1 to 11 ₉ and the back surface-side nozzle headers ₁₂ 1 to 12 ₉ the flow rate of the cooling gas injected from the nozzle header 12 ₁ to 12 ₉ longitudinally, i.e. can be made uniform in the width direction of the steel strip S.

Therefore, even if only from the longitudinal side of each surface-side nozzle headers 11 ₁ to 11 ₉ and the back surface-side nozzle headers 12 ₁ to 12 ₉ cooling gas can only be installed in a narrow place that can not be turned , It doesn't matter.
Then, each of the steel strip S in each surface-side nozzle headers 11 ₁ to 11 ₉ and the back surface-side nozzle headers 12 ₁ to 12 ₉ opening 15 and the opening 15 formed on the closed end side is formed on the open end of the The pressure equalizing pipe 16 is arranged outside each of the one side end portion and the other side end portion in the width direction of the steel strip S, and is longer than the width size of the steel strip S. Therefore, the flow rate of the cooling gas injected from the surface side nozzle headers 11 ₁ to 11 ₉ and the back surface-side nozzle headers 12 ₁ to 12 ₉ can be reliably equalized over the entire width direction of the steel strip S ..

On the other hand, in FIG. 4 is a schematic configuration of the first stage of the surface-side nozzle headers 11 ₁ for use in the gas jet cooling device according to the reference example is shown.
Figure 4 surface-side nozzle headers 11 ₁ shown in is surface-side nozzle headers 11 ₁ to the basic configuration shown in FIG. 3 are similar, unlike surface-side nozzle headers 11 ₁ shown in FIG. 3, the surface-side nozzle headers 11 ₁ No openings are formed on the open end side and the closed end side in the longitudinal direction on the back side of the gas injection port 13, and the pair of openings are not connected to each other by a pressure equalizing pipe.

In this case, the longitudinal direction of the pressure inside the surface-side nozzle headers 11 _1, the pressure of the closed end side is high, the pressure of the open end side becomes low. Therefore, the flow rate of the cooling gas injected from the surface side nozzle headers 11 _1, fast closed end side in the longitudinal direction, the open end side becomes slow. As a result, the cooling temperature deviation in the width direction of the steel strip S increases.
Therefore, if only from the longitudinal side of each surface-side nozzle headers 11 ₁ to 11 ₉ and the back surface-side nozzle headers 12 ₁ to 12 ₉ cooling gas can only be installed in a narrow place which can not be turned on, a problem.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and various modifications and improvements can be made.
For example, the gas jet cooling device 1 can be applied to other than the in-line coater (resin coating coating device) in the continuous annealing equipment as long as the steel strip S is cooled by the cooling gas.
Further, the nozzle headers are provided with 9 steps on the front surface Sa side of the steel strip S and 9 steps on the back surface Sb side of the steel strip S, but the number is not limited thereto. For example, only one steel strip S may be provided on the front surface Sa side, or only one steel strip S may be provided on the back surface Sb side. Further, a plurality of nozzle headers may be provided only on the front surface Sa side of the steel strip S, or a plurality of nozzle headers may be provided only on the back surface Sb side of the steel strip S.

The surface-side nozzle headers ₁₁ 1 to 11 ₉ and the back surface-side nozzle headers ₁₂ 1 to 12 ₉ have been formed in a cylindrical shape, but not limited to a cylindrical shape if cylindrical.
Further, the gas injection port 13 has been formed in a rectangular slit elongated in the longitudinal direction, along the longitudinal direction of the surface side nozzle headers 11 ₁ to 11 ₉ and the back surface-side nozzle headers 12 ₁ to 12 ₉ It may be formed by a plurality of openings provided at a substantially uniform pitch.
Further, although the steel strip S is described as an example of the cooling target of the gas jet cooling device 1, the cooling target is a strip-shaped object other than the steel strip S, for example, a non-ferrous metal such as copper, aluminum, or titanium. It may be coiled) or the like.

And when cooled the steel strip S in the gas jet cooling device having a surface-side nozzle headers 11 ₁ to 11 ₉ of similar 1-step to 9-stage and 3 as an example, similar surface side nozzle and FIG. 4 as a comparative example the steel strip S in the case of cooling with a gas jet cooling device having a header 11 ₁ to 11 _9, was investigated deviation of longitudinal flow velocity of the cooling gas.
Incidentally, Examples and the surface-side nozzle headers ₁₁ 1 to 11 ₉ of nominal diameter 250A of the comparative example, the length of the steel strip width direction of the gas injection port 13 is 1880 mm, width of the gas injection holes 13 is 10 mm, the The flow rate of the cooling gas introduced from the end of the opening was 68 m ³ / min. The cross-sectional dimensions of each surface-side nozzle headers ₁₁ 1 to 11 provided in ₉ equalizing pipe 16 in the examples was a 75mm width 150 mm × height. Therefore, the cross-sectional area perpendicular to the longitudinal direction of the pressure equalizing pipe 16 was about 22% of the cross-sectional area perpendicular to the longitudinal direction of the surface side nozzle headers 11 ₁ to 11 _9.

Longitudinal flow velocity of the cooling gas, since the internal longitudinal pressure closed end side of the surface-side nozzle header ₁₁₁ is large, the position B (FIG longitudinal end of the closed end side of the gas injection port 13 3) is the maximum, and the gas injection port 13 is the minimum at the position A (see FIG. 3) of the end portion on the opening end side in the longitudinal direction.
The flow velocity ratio in the longitudinal direction of the cooling gas in both the case of the gas jet cooling device of the example and the case of the gas jet cooling device of the comparative example is shown in FIG. 5 with the position B as 100%. In the case of the gas jet cooling device of the comparative example, the flow velocity of the position A is reduced by 28.0% with respect to the position B, whereas in the case of the gas jet cooling device of the embodiment, the flow velocity of the position A is reduced with respect to the position B. Decreased only 10.6%.

Therefore, in the case of a gas jet cooling device for example, the flow rate of the cooling gas injected from the surface side nozzle headers 11 ₁ to 11 _9, as compared with gas jet cooling device of the comparative example, the longitudinal direction Was able to approach evenly.
In the gas jet cooling device of the embodiment, the opening end of the gas injection port 13 in the longitudinal direction is set to the median flow rate of 50.5 m / s of the cooling gas at the ^{maximum air volume (2778 m 3 / min) in the case of the actual machine.} A flow velocity difference of 5.9 m / s is expected between the flow velocity at the position A of the side end and the flow velocity at the position B of the end on the closed end side in the longitudinal direction of the gas injection port 13. When the flow velocity of the cooling gas is 47.55 m / s at position A and 53.45 m / s at position B, the plate temperature difference is about 1.2 to 1.3 ° C. There was no problem with the quality of. That is, the ratio of the deviation (5.9 m / s) to the average value (50.5 m / s) of the flow velocity in the longitudinal direction of the cooling gas, that is, the degree of decrease in the flow velocity ratio of the position A to the position B is about 12%. I confirmed that there was no problem.

Also, the case of cooling the steel strip S in the gas jet cooling device having a backside nozzle header 12 ₁ to 12 ₉ of similar 1-step to 9-stage and 3 as an example, similar to the back surface and 4 as a comparative example in the case of cooling the steel strip S in the gas jet cooling device embodiment having a side nozzle headers 12 ₁ to 12 _9, was investigated deviation of longitudinal flow velocity of the cooling gas.
Again, the nominal diameter of the back surface-side nozzle headers ₁₂ 1 to 12 ₉ 250A, the length of the steel strip width direction of the gas injection port 13 is 1880 mm, width of the gas injection holes 13 is 10 mm, introduced from the open end The flow rate of the cooling gas was set to 68 m ³ / min. The cross-sectional dimension of each back side nozzle headers ₁₂ 1 to 12 ₉ equalizing pipe 16 provided in the examples was a 75mm width 150 mm × height. Therefore, the cross-sectional area perpendicular to the steel strip width direction of the pressure equalizing pipe 16 was about 22% of the cross-sectional area perpendicular to the steel strip width direction of each of the back surface-side nozzle headers 12 ₁ to 12 _9.

Although not shown, the flow velocity ratio of the cooling gas in the longitudinal direction in both the case of the gas jet cooling device of the example and the case of the gas jet cooling device of the comparative example is not shown, but the gas of the comparative example is set to 100%. In the case of the jet cooling device, the flow velocity at position A decreased by 28.2% with respect to position B. On the other hand, in the case of the gas jet cooling device of the embodiment, the flow velocity at the position A decreased by 10.2% with respect to the position B.
Therefore, in the case of a gas jet cooling device for example, the flow rate of the cooling gas injected from the back surface side nozzle headers 12 ₁ to 12 _9, as compared with gas jet cooling device of the comparative example, the longitudinal direction Was able to approach evenly.

1 Gas jet cooling device 10 Cooling gas introduction duct 11 _{1 to} 11 ₉ Surface side nozzle header (nozzle header)
11a Open end side end 11b Closed end side end 12 _{1 to} 12 ₉ Back side nozzle header (nozzle header)
13 Gas injection port 14 Closed body 15 Opening 16 Pressure equalizing pipe 16a Pressure equalizing pipe body 16b Lid 17 Roll S Steel strip (cooling object)
Sa front side Sb back side

Claims (5)

It is equipped with a nozzle header that extends in the longitudinal direction and has a gas injection port on the side facing the object to be cooled.
One end of the nozzle header in the longitudinal direction is an open open end, the other end of the nozzle header in the longitudinal direction is a closed closed end, and the nozzle header is from the open end. The cooling gas supplied to the inside flows in one direction toward the closed end.
A pressure equalizing pipe is provided to connect an opening formed on one side of the nozzle header in the longitudinal direction and an opening formed on the other side on the back side of the gas injection port of the nozzle header. A gas jet cooling device characterized by. The gas jet cooling device according to claim 1, wherein the object to be cooled is a steel strip. The nozzle header is installed so that its longitudinal direction is the width direction of the steel strip, and the opening formed on one side of the nozzle header in the longitudinal direction and the opening formed on the other side, respectively. Is arranged outside the width direction of each of the one side end portion and the other side end portion in the width direction of the steel strip, and the pressure equalizing pipe is longer than the width size of the steel strip. Item 2. The gas jet cooling device according to Item 2. The invention according to any one of claims 1 to 3, wherein the cross-sectional area orthogonal to the longitudinal direction of the pressure equalizing pipe is set to 5% or more of the cross-sectional area orthogonal to the longitudinal direction of the nozzle header. Gas jet cooling system. A gas jet cooling method comprising cooling an object to be cooled by using the gas jet cooling device according to any one of claims 1 to 4.

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