JPS6223620B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminar flow nozzle that maintains the discharge flow from the nozzle in a laminar flow and can easily control the maximum/minimum flow ratio to any value of 2 or more.

BACKGROUND ART In hot rolling factories and the like, heated thick steel plates are subjected to laminar flow cooling in order to improve the material quality of the steel plates. This laminar flow cooling
As shown in the explanatory diagram in Fig. 1, the circular tube nozzle 1 has a circular laminar flow in which water flows down from the circular opening at the lower end of the vertically arranged laminar flow, and a flat rectangular opening that is arranged vertically. A flat laminar flow is known in which water is caused to flow down from a rectangular opening at the lower end of the flat nozzle 2 in a vertical or near-vertical line to form a flat laminar flow (liquid film thickness a<<liquid film width b).

Laminar flow is characterized by the fact that the flow velocity at the time of collision with the steel plate is maintained as it is, and the flow continues to spread in a laminar manner even after the collision, but in circular tube laminar flow, the flow velocity remains constant after collision with the steel plate. as long as the water film thickness decreases. Therefore, as shown in FIG. 1, in the circular laminar flow, the circular laminar flow 4 flowing down from the circular tube nozzle 1 collides with the steel plate 3 and spreads radially, and water splash 5 occurs, and the circle in which this water splash 5 occurs The inside is the area that is cooled.

On the other hand, in the flat laminar flow, the flat laminar flow 6 that flows down from the flat nozzle 2 collides with the steel plate 3 and is split to the left and right, but the flow becomes a substantially one-dimensional flow and no reduction in the water film occurs. Therefore, in the case of the flat laminar flow, water splash does not occur after colliding with the steel plate 3, so the cooling capacity is high, and it is superior to the circular tube laminar flow in terms of cooling uniformity and cooling capacity.

FIG. 2 is a perspective view of a flat laminar flow nozzle, and FIG. 3 is a sectional view taken along the line AA in FIG. 2, and 7 is a header to which the nozzle 2 is attached. The nozzle 2 has a hollow cross section as shown in FIG.
There are also honeycomb-like shapes as shown in Figure 4.

Flat laminar flow has the above-mentioned advantages, but on the other hand, it has a drawback in the controllability of cooling capacity. That is, in order to control the cooling capacity, it is sufficient to control the flow rate of water discharged from the flat nozzle 2, but in the conventional nozzles shown in FIGS. 2 to 4, the nozzle in FIG. Gap dimension a
As can be seen from the diagram showing the relationship between the nozzle gap size a and the minimum discharge flow velocity V, there is a minimum discharge flow velocity V that can maintain laminar flow depending on the nozzle gap dimension a, and when the water flow rate is lower than this minimum discharge flow velocity, the nozzle As a result of air getting inside, the discharge flow becomes intermittent dripping water with discontinuous and non-uniform particle sizes, making it impossible to maintain a laminar flow. When the steel plate 3 heated by such intermittent dripping water is cooled, the intermittent dripping water entrains air when it collides with the steel plate 3, making the water density non-uniform. As a result, the cooling capacity becomes unstable and the steel plate 3 cannot be cooled uniformly.

On the other hand, when the cooling capacity is increased by increasing the flow rate of water discharged from the flat nozzle 2, the discharge flow velocity at the nozzle outlet increases. As a result, when the Reynolds number at the nozzle outlet exceeds about 5×10 ⁴ , the discharge flow becomes a turbulent jet flow and a flat laminar flow cannot be obtained. When the heated steel plate 3 is cooled by such a jet stream, the jet stream that collides with the surface of the steel plate 3 is immediately scattered because the energy of the jet stream is large. Therefore, even if the discharge flow rate is increased, the cooling capacity does not increase, and in some cases decreases.

From the above, although it is originally necessary to control the cooling capacity by setting the maximum/minimum flow rate ratio to 5 or more depending on the thickness of the steel plate to be cooled, etc., in the conventional flat nozzle 2, Nozzle gap dimension a
When the flow rate was 25 mm or less, the range in which the flow rate could be controlled was a low value of about 2 to 3 in terms of maximum/minimum flow rate ratio.

In addition, in order to increase the amount of water discharged from the flat nozzle 2 in order to increase the cooling capacity, the nozzle gap size a
must be increased, but the nozzle gap dimension a
As is clear from FIG. 5, when , the minimum discharge flow rate increases and the controllability of the cooling capacity deteriorates.

That is, in order to make the discharge flow laminar, the Reynolds number (Re) expressed by the following general formula should be 5×10 ⁵
Must be as follows.

Re=4・a・b・V/V・2・(a+b)……(1
) However, if the nozzle gap size a is large, a
≪Under the condition b, the Ray nozzle number (Re) becomes a large value, and it is difficult to reduce it to 5×10 ⁵ or less.Experience shows that when the nozzle gap dimension a becomes 50 mm or more, the formation of flat laminar flow occurs. It turned out to be difficult.

Therefore, if it is desired to increase the amount of water discharged in order to increase the cooling capacity, it is necessary to use a plurality of flat nozzles with small gaps. As a result, the density of the amount of water on the heated steel plate 3 is not uniform and there are areas where the density of the water is low, which limits the improvement of the cooling capacity and complicates the equipment.

From the above-mentioned viewpoints, the present invention can maintain the discharge flow from the nozzle in a laminar flow, and can arbitrarily and easily control the maximum/minimum flow rate ratio to 2 or more, especially when the nozzle gap is large. Even with flat nozzles, we provide laminar flow nozzles that can maintain laminar discharge flow and easily control the flow rate. In a laminar flow nozzle in which a rectangular discharge port is formed, the inside of the rectangular box is partitioned by providing at least one partition plate extending between the short side walls and parallel to the long side walls. Accordingly, the nozzle chamber is divided into at least two flat nozzle chambers, and each inlet of the nozzle chamber is provided with a valve that can be opened and closed.

Next, the present invention will be explained with reference to examples and drawings.

FIG. 6 shows a sectional view of the nozzle of the present invention, FIG. 7 shows an enlarged perspective view of the nozzle body, and FIG. 8 shows an enlarged sectional view of the valve body. In the drawing, 8 is a nozzle main body, 9
is a valve body part provided at the upper part of the nozzle main body part 8. The nozzle main body 8 has opposing long side walls 8a,
8b, and short side walls 8c and 8d, and inside the box, there is a partition plate 10 extending between the short side walls 8c and 8d and parallel to the long side walls 8a and 8b.
A flat nozzle chamber 12,1 partitioned by 11
3 and 14 are formed. A flat rectangular discharge port 15 having a small width a and a large length b and having a larger opening area than a conventional nozzle is provided on the lower end surface of the nozzle main body 8.

The height c of the partition plates 10 and 11 is the same as that of the nozzle chamber 12,
It is necessary to make the width approximately 10 times or more the width e of the nozzle chambers 13, 14, so that the water flowing down inside the nozzle chambers 12, 13, 14 can be made into a laminar flow. Partition plate 1
The tips of the nozzles 0 and 11 are formed into acute angles to prevent bubbles from being generated or the flow to be disturbed when the water flow discharged through the nozzle chambers 12, 13, and 14 leaves the tips. ing.

The tips of the partition plates 10 and 11 may protrude from the discharge port 15 or may be located inward from the discharge port 15. Note that the dimension between the tips of the partition plates 10 and 11 and the discharge port 15 is preferably within the width dimension a of the discharge port 15 based on experience.

The width dimension e of the nozzle chambers 12, 13, 14 is equal to or higher than the minimum discharge flow rate at which the water discharged from the nozzle chambers 12, 13, 14 can form a laminar flow, and the width dimension e is equal to or higher than the minimum discharge flow rate at which the water discharged from the nozzle chambers 12, 13, 14 can form a laminar flow, and
It is desirable to set the range of 3 to 25 mm so that the Reynolds number (Re) shown in the formula satisfies 5×10 ⁵ or less. That is, if the width dimension e is less than 3 mm, impurities contained in the water will be absorbed into the nozzle chambers 12, 13, 14.
On the other hand, if the width dimension e exceeds 25 mm, the minimum discharge flow velocity will increase, and as a result, slight fluctuations in the amount of water will cause a large change in the laminar flow state of the discharge water. This causes changes and makes it impossible to obtain stable laminar flow.

The valve body part 9 is a rectangular box body formed in the upper part of the nozzle body part 8, extending in the long side direction and having a width dimension larger than that of the nozzle body part 8, and whose inside communicates with the nozzle body part 8. 8 nozzle chamber 1
A valve 16 that can open and close the upper part of 2, 13, 14,
17 and 18 are provided.

The valves 16, 17, 18 are connected to the nozzle chambers 12, 13,
14 upper openings 12a, 13a, 14a in the length and width directions, and consists of a lid-like body that can completely close the upper openings 12a, 13a, 14a, with one end 16a, 17a, 18
a is pivotally mounted by shafts 19, 20, and 21 to a mounting seat 22 that projects outward from the long side wall 8a of the nozzle body 8 so as to be able to rise and fall freely. In addition, valves 16, 17,
The other end of 18 is provided with flanges 16b, 17b, 18b that abut on the upper surfaces of the partition plates 10, 11 and the long side wall 8b of the nozzle body 8.

That is, the valve 16 closes the nozzle chamber 12 by having the end surface of the flange 16b abut against the top surface of the partition plate 10 in its collapsed state, and the valve 17 closes the nozzle chamber 12 by having the end surface of the flange 17b contact the top surface of the partition plate 11 in its collapsed state. The valve 18 closes the nozzle chamber 13 by coming into contact with the
The end surface of the flange 18b contacts the upper surface of the long side wall 8b of the nozzle body 8, thereby closing the nozzle chamber 14. Note that the undulations of the valves 16, 17, and 18 are, for example, the flanges 16b and 18, although not shown.
The operation can be easily performed by providing an operating shaft protruding from the end faces of 17b and 18b, causing the operating shaft to protrude from a curved slit provided in the short side wall of the valve body portion 9, and operating the operating shaft. can.

Since the present invention is configured as described above, the valves 16, 17, and 18 are erected to open the nozzle chamber 1.
When all 2, 13, and 14 are left open, the water that enters the nozzle body 8 from the valve body 9 is
The water is discharged in a laminar flow from the discharge port 15 through the nozzle chambers 12, 13, and 14, and the heated steel plate 3 is efficiently cooled with a larger amount of discharged water than before and in a good flat laminar flow state. be able to.

Next, when controlling the maximum/minimum flow rate ratio of the discharged water amount, the valves 16, 17, and 18 are lowered,
By sequentially closing the nozzle chambers 12, 13, and 14, the amount of water discharged from the discharge port 15 can be accurately controlled in a good flat laminar flow state. Note that the flow velocity in this case is constant.

In addition to the control by such valves 16, 17, and 18, the entire discharge flow rate from the discharge port 15 is controlled by
Of course, it is also possible to control the flow rate ratio by adjusting it within the minimum flow rate to maintain laminar flow.

In the embodiment described above, three nozzle chambers were formed by providing two partition plates, but even if two nozzle chambers were formed by one partition plate,
Of course, four or more nozzle chambers may be formed by three or more partition plates.

As described above, according to the present invention, a large-gap flat nozzle is formed by stacking small-gap flat nozzles each having a plurality of compartments, and each of the small-gap flat nozzles is opened and closed by a plurality of valves. As a result of controlling the discharge flow rate from the gap flat nozzle, the heated steel plate can be efficiently cooled with a larger amount of water than before while maintaining the discharge flow from the nozzle in a laminar flow. , and the maximum/minimum flow rate ratio can be arbitrarily and easily controlled to 2 or more, which brings about industrially excellent effects.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing conventional laminar flow cooling, Fig. 2 is a perspective view of a conventional flat laminar flow nozzle, Fig. 3 is a cross-sectional view taken along line A-A in Fig. 2, and Fig. 4 is another 5 is a diagram showing the relationship between the nozzle gap and the minimum discharge flow velocity, FIG. 6 is a sectional view of the nozzle of the present invention, and FIG. 7 is a valve body portion. Enlarged perspective view,
FIG. 8 is an enlarged sectional view showing the nozzle main body.
In the drawings, 3... Steel plate, 8... Nozzle body, 8a, 8b... Long side wall, 8c, 8d... Short side wall, 9... Valve body part, 1
0, 11... Partition plate, 12, 13, 14... Nozzle chamber, 12a, 13a, 14a... Upper opening, 15...
Discharge port, 16, 17, 18... Valve, 16a, 17
a, 18a... end of valve, 16b, 17b, 18b
...Flange, 19, 20, 21...Shaft, 22...Mounting seat.

Claims (1)

[Claims] 1. In a laminar flow nozzle in which a flat rectangular discharge port is formed on the lower surface of a rectangular box consisting of opposing long side walls and short side walls, the inside of the rectangular box is , by providing and partitioning at least one partition plate parallel to the long side wall between the short side walls, the nozzle chamber is divided into at least two flat nozzle chambers, and at each entrance of the nozzle chamber. , a laminar flow nozzle characterized by having valves that can be opened and closed respectively.