A gas-liquid cooling apparatus having a group of gas jet nozzles and a group of liquid jet nozzles so that the gas jet stream from the gas jet nozzles intersects with the liquid jet stream from the liquid jet nozzles at an acute angle so as to form a gas-liquid mixture, the improvement comprising a liquid guide means for collecting the liquid which is separated from the gas-liquid mixture and which is reflected from a material to be cooled and for carrying the collected liquid away from the material.

The present invention relates to a gas-liquid mixture jet cooling apparatus 
suitable for cooling a band-shaped material, especially a steel plate 
strip in the course of its successive heat treatments. 
There has been a marked tendency of late for the heat treatment of a steel 
plate strip to be made in the course of high speed transfer of the strip 
within a continuous heat treating furnace. The cooling of such strip in 
the course of its transfer is important. 
As a cooling means for the steel strip, there is one means that utilizes a 
stream of a gas-liquid mixture (hereinafter referred to as "a 
gas-liquid"). This has the advantage of having a wide range of cooling 
rates but since the handling thereof after the completion of injection of 
the gas-liquid is cumbersome, it is difficult to control cooling and no 
satisfactory means to do so has been developed so far. 
The term "gas-liquid" or "gas-liquid mixture" as used herein refers to a 
fluid which is produced by a process in which a high speed gas and a 
liquid of a predetermined pressure are injected from their respective 
nozzles as jet streams and these streams are then mixed with each other by 
being crossed with each other so that the liquid (e.g., water) is broken 
up into fine particles mixed in the gas in the form of mist, or in a form 
almost equivalent to spray. 
A gas-liquid cooling apparatus has been proposed, which comprises a series 
of gas jetting slit nozzles in a row and a series of liquid jet nozzles in 
a row wherein the gas jetting slit nozzles have a plurality of parallel 
gaps defined by a desired number of spacers while the liquid jet nozzles 
are provided with a number of small holes so that streams of a liquid 
discharged therefrom intersect with those of a gas discharged from the gas 
jet nozzles at an acute angle. 
In the conventional gas-water cooling apparatus, a gas-water jet is applied 
to the surface of a hot strip and, thus, the water separated from the 
gas-water jet after its collision with the hot strip scatters over that 
surface and therearound which not only interferes with the continuation of 
gas-water jetting but also causes irregularities in the cooling rate 
thereof, which is represented by the heat transmission efficiency 
[Kcal/m.sup.2 hr.degree. C.] or the cooling velocity [.degree.C./sec] with 
respect to a steel plate (strip) having a predetermined temperature and 
spaced at a predetermined distance from the front end of the nozzle and 
which is determined by the density of the air (Nm.sup.3 /m.sup.2 min) and 
that of the water (l/m.sup.2 .multidot.min) used. For example, when the 
scattered water remains on the surface of the strip in the form of a water 
film, the gas-water ejected thereon can cool the surface only indirectly 
through the film so that the cooling rate is reduced and irregularities in 
cooling take place. Such irregularities make it difficult to control 
cooling. 
Further, the scattering of water around the strip is not desirable because 
such scattered water is driven toward the strip during the continuation of 
the gas-water injection. 
On the other hand, when, in a continuous annealing line, a hot strip heated 
up to and kept at a high temperature in heating and soaking sections is 
quenched in a cooling section to thus follow a desired heat treating 
pattern and is subsequently transferred to an overaging section, it is 
desirable that the strip be transferred to the above mentioned overaging 
section while it is kept at its finally required temperature. 
Furthermore, the spacers define gas jetting passages which are spaced 
equidistantly side by side in a line and which extend in a parallel 
relationship with the gas jetting direction. Each of the spacers has a 
tapered front (outer) end and a tapered rear (inner) end. These ends are 
inclined inwardly with respect to the center axis of the corresponding 
spacers. However, due to the tapered front ends of the spacers, the 
resultant stream of gas-liquid mixture tends to be broken into several 
parts in the direction of the row of nozzle (see FIG. 11) and it is 
impossible for the nozzle to form a spray pattern uniformly distributed in 
the direction of the row of nozzles. 
The above phenomenon has been considered to be due to the streams of gas 
generated between the liquid nozzles, which streams separate the entire 
stream of the mixture and it would therefore be possible to prevent such 
separating or division of the stream of the mixture if the above mentioned 
gas streams generated between the liquid nozzles were eliminated. 
The primary object of the present invention is to remove from the surface 
of the cooling material and therearound the water separated from the 
gas-water quickly and properly to thereby provide an atmosphere suitable 
for performing effective and uniform cooling and its control. 
The secondary object of the present invention is to make sure that the 
formation of rifts in the gas-liquid stream can be prevented. 
According to the present invention, the liquid (e.g., water) separated from 
the gas liquid after the completion of cooling of the material to be 
cooled (strip) is removed from the material and the space therearound. 
The gas liquid cooling apparatus of the present invention comprises a gas 
jet nozzle (or nozzles) arranged close to the material (e.g. a hot steel 
plate strip and the like), a liquid jet nozzle (or nozzles), a gas supply 
header, and a liquid supply header. 
According to an embodiment of the present invention, the gas jet nozzle 
comprises a slit of a predetermined width or a plurality of rectangular 
small holes each capable of discharging a high speed gas jet stream 
upwardly with respect to the horizontal plane so that a gas stream in the 
shape of a riftless gas curtain is formed extending in the direction of 
the width of the material to be cooled. 
As a gas source, air may be used, but to cool a hot steel strip and the 
like, it is advantageous to use inert gases (such as N.sub.2 gas, CO.sub.2 
gas, Ar gas etc.) because they are effective for the prevention of 
oxidation and they may be collected for re-use. 
When these gases are re-used, it is desirable to cool and dehumidify them. 
According to the present invention, preferably, the liquid jet nozzle 
comprises a group of small nozzle holes angled upwardly with respect to 
the horizontal plane at positions right beneath the gas jet nozzle so that 
each of them discharges a jet stream intersecting with the gas jet stream 
from the gas jet nozzle to obtain an upwardly angled gas-liquid mixture 
which is formed outside the apparatus. 
As a liquid source, water is preferable for of economy but other liquids 
may be used so long as they have sufficient cooling capacities and they 
are not detrimental to the material to be cooled. 
Preferably, the liquid jet nozzle is positioned below the gas jet nozzle 
because by so doing, it is possible to obtain a uniform flow rate of 
discharge in the direction of the width of the material even when the flow 
rate of the liquid is varied. 
Referring to the angle of discharge of the gas-liquid, preferably, the 
gas-liquid mixture obtained by the above described process is directed 
onto the vertically moving material to be cooled, upwardly with respect to 
the horizontal plane, for example, at a velocity of about 40 to 100 m/sec. 
The greater part of the gas-water thus directed is reflected upwardly by 
the surface of the material in the direction opposite to the direction of 
discharge of the gas liquid just like in the relationship of an incidence 
angle and a reflection angle and is then separated into gas and liquid. 
If the gas-liquid is directed in the horizontal direction, the preceding 
gas-liquid and the succeeding gas-liquid will interfere with each other 
and, as a result, they will scatter on the surface of the material and 
therearound to finally form or become liable to form a liquid film on that 
surface so that irregularities may take place or would be liable to take 
place during cooling and hence it would become difficult to produce 
effective cooling or cooling control. 
From the above explanation, it will be understood that it is possible to 
effect gas-liquid cooling uniformly and effectively by directing the 
gas-liquid upwardly with respect to the horizontal direction. 
Regarding the angle of discharge of the gas-liquid, any angle can achieve 
the purpose of the invention provided that it is sufficient to cause the 
gas-liquid to be directed upward with respect to the horizontal plane but 
in practice, it is established depending on the distance between the 
gas-liquid jet unit (gas and liquid jet nozzles) and the material to be 
cooled and the position and the configuration of a liquid guide plate 
which will be described hereinafter. This guide plate receives and drives 
liquid separated from the gas-liquid due to the reflection of the latter 
from the material being cooled. 
The liquid guide plate is adapted to receive the greater part of the liquid 
separated from the gas-liquid and to carry it away quickly from the 
material to be cooled. Accordingly, it is arranged at a position where the 
above described separated liquid falls down. In actual practice, it may be 
in the form of any inclined plate capable of guiding the liquid it 
receives on or above the gas header to a position away from the material 
as completely as possible and the angle of inclination and the dimensions 
thereof can be determined properly in proportion to the amount of the 
liquid. 
The liquid guide plate may be in the form of a flat plate or a trough or 
the like. 
With the above structure, the greater part of the injected gas-liquid is 
separated quickly and positively from the material to be cooled and, 
therefore, a uniform gas-liquid cooling can be achieved. 
As a result, it can produce an effect that the cooling control for the 
material can be easily carried out. 
According to the present invention, the gas-liquid jet units may be 
provided in a plurality of layers on opposite sides of the material to be 
cooled which continuously travels in the vertical direction to thereby 
obtain a predetermined cooling rate using a plurality of the units. 
With such multiple units, it is desirable that the gas-liquid jet units be 
arranged in such a manner that the gas-liquid discharge positions of the 
units facing one side (the front surface) of the material to be cooled and 
those of the units facing the other side (the rear surface) thereof do not 
overlap but are displaced from each other vertically or in the right and 
left directions or in both of these directions, so that both surfaces of 
the material can be cooled uniformly. 
If the units are arranged in the above fashion, the material can be cooled 
without giving rise to an undesirable effect on its configuration. 
Further, with such an arrangement, even a narrow material can be cooled 
without its side portions being affected adversely since the gas-liquid 
jets applied outside the material do not run against one another. 
It is possible to provide a cooling chamber by shielding the above 
described multilayered gas-liquid jet units in their entireties with 
shielding plates blocking out the atmosphere and to make such cooling 
chamber a one unit cooler. Also it is possible to use a plurality of such 
cooler units. 
In the cooling chamber of the above structure, it is possible to vary the 
cooling rate by controling the individual cooler units by ON-OFF 
operations. 
Further, the gas and the liquid (water) separated from the gas-liquid after 
discharge as explained hereinbefore can be removed by means of separate 
exhaust means through gas exhaust ports provided, for example, on both 
sides of the cooling chamber and through liquid exhaust ports provided, 
for example, at the bottom of the chamber, respectively. The discharged 
gas and liquid can be re-used after they are collected and treated.

Referring to FIGS. 1-4, reference numeral 21 indicates a gas supply header 
which is connected to a gas supply source (not shown), and 22 indicates 
nozzle forming plates attached to the gas supply header 21 in the 
longitudinal direction of the latter. These nozzle forming plates 22 which 
constitutes part of first nozzle means are spaced from one another at a 
predetermined distance and are held by bolts 13 to provide therebetween a 
slit-like gas jetting nozzle opening 24. 
To the plates 22 is attached a unit pipe 26 in the vicinity of the opening 
24. The unit pipe 26 is held by brackets (not shown) which are connected 
to the plates 22 by means of the bolts 13. The pipe 26 has a plurality of 
liquid jet nozzles 27 arranged at predetermined intervals so that a liquid 
is discharged therefrom just in front of the nozzle opening 24. Pipe 6 and 
nozzles 27 constitutes second nozzle means. 
Spacers 25 positioned between plates 22 define a group of gas jet nozzles 
in the form of parallel rectangular ports 24A within the nozzle opening 
24. The liquid jet nozzles 27 are located below and adjacent to the gas 
jet nozzles 24A. The spacers 25 and the nozzle forming plates 22 
constitute the first nozzle means. 
These nozzles 24A are directed upward with respect to the horizontal plane 
at an angle of inclination of .alpha. and the nozzles 27 are directed 
upward so as to intersect with the corresponding nozzles 24A at an acute 
angle so that the gas jet discharged from each of the nozzles 24A and the 
liquid discharged from each of the nozzles 27 are mixed in front of the 
nozzles 24A to produce an upwardly directed gas-liquid jet flowing, for 
example, at a velocity of 40 to 100 m/sec. 
As a gas source, for example, N.sub.2 gas of nearly 1500 mm Aq is supplied 
through the gas supply header 21 while a suitable quantity of liquid is 
supplied through the unit pipe 26 which is connected to the liquid supply 
source (not shown). The upper nozzle forming plate 22 which forms a part 
of the gas supply header 21 is inclined rearwardly of each of the nozzles 
24A and receives and conducts the liquid, which is reflected from the 
vertically moving hot strip 100 and separated from the gas-liquid, away 
from the strip. Instead of the provision of inclined nozzles 24A and 
plates 22, these may be horizontal. However, in this case the apparatus 
itself is installed at an angle of .alpha., with respect to the horizontal 
plane. 
If necessary, a cover 28 which is a part of the plate 22 can be provided on 
the nozzles 24A to protect the liquid nozzles 27 in case the strip runs 
against the gas-liquid jet unit 40 accidentally. However, it goes without 
saying that even with the cover 28, no change will take place in the 
functioning of the unit. 
The spacers 25 are identical to spacers 5 of an embodiment illustrated in 
FIGS. 5-9, which will be explained hereinafter. 
FIGS. 5-9 illustrate another embodiment of the present invention. The gas 
supply header 1 is connected to a gas supply source (not shown). The 
nozzle forming plates 2 are attached to the gas supply header 1 in the 
longitudinal direction. These nozzle forming plates 2 which form part of 
first nozzle means are spaced from one another at a predetermined distance 
and are held by bolts 13 to provide therebetween a slit-like gas jetting 
nozzle opening 4. 
To the plates 2 is attached a unit pipe 6 which constitutes a second nozzle 
means in the vicinity of the opening 4. The unit pipe 6 is held by 
brackets 15 which are connected to the plates 2 by means of the bolts 13 
and retaining plates 14 (FIG. 7). The pipe 6 has a plurality of liquid jet 
nozzle holes 7 arranged at predetermined intervals so that a liquid is 
discharged therefrom just in front of the nozzle opening 4. The liquid is 
supplied through connecting pipes 8 from a liquid supply pipe 3 which is 
connected to a liquid supply source 48 (FIG. 12) and which is held by the 
brackets 15. 
In the embodiment shown in FIGS. 5-9, the nozzle opening 4 extends 
horizontally and the nozzle holes 7 open in the direction intersecting the 
horizontal extension of the opening 4 at an acute angle. 
A plurality of spacers 5 are interposed between the nozzle plates 2 at 
predetermined intervals in the longitudinal direction of the nozzle plates 
2 in such a manner that each of the spacers 5 extends parallel to the gas 
jetting direction and by these spacers there are formed a group of gas jet 
nozzles in the form of spaced parallel rectangular ports 4A within the 
nozzle opening 4. Thus, a harmonica type of nozzle arrangement is provided 
which constitutes the first nozzle means. 
Each of the spacers 5 has a tapered inner or rear end 5B and a flat outer 
or front end 5A, according to the present invention. 
By the provision of the spacers 5 with flat front ends at predetermined 
intervals over the entire width of the slit-like gas jetting nozzle 
opening 4, negative pressure or vacuum zones are provided in front of and 
adjacent to the spacers 5, respectively, due to the jet streams discharged 
from the ports 4A on both sides of each of the spacers 5 and, therefore, 
the streams of the gas-liquid mixture which are formed by a gas discharged 
from the ports 4A and a liquid discharged from the liquid jet nozzle holes 
7 located on both sides of each of the spacers 5 and which are formed at 
positions just in front of the group of the gas jet nozzles 4A, are 
attracted to one another due to the existence of the above described 
vacuum zones so that a curtain like jet stream of mixture A (FIG. 10) is 
obtained, which is uniformly distributed in the direction of the width of 
the entire nozzle. 
The attraction is considered to be due to the so called "Coanda effect" in 
fluid mechanics. 
The steel strip 100 is conveyed in the vertical direction, i.e. in a 
direction perpendicular to the plane of the drawing. 
In a prior art apparatus, the spacers 5' do not have flat front ends, and 
accordingly, no Coanda effect occurs, so that the mixture A' is separated 
into several streams, as described above and as illustrated in FIG. 11. 
That is, no vacuum zone is produced in front of each of the spacers 5'. 
As described above, it will be understood that the gas-liquid cooling 
apparatus according to the present invention makes it possible to obtain a 
spray pattern uniformly distributed in the direction of the width of the 
liquid jet nozzle. Furthermore, according to the present invention, the 
diameter of the nozzle holes can be increased to increase the cooling 
rate, while ensuring the provision of the curtain like gas-liquid stream. 
An example of an arrangement in which a plurality of the gas-liquid jet 
units 40 shown in FIGS. 1 and 2, according to the present invention are 
provided in a plurality of layers and on different levels is shown in 
FIGS. 12 and 13. The units are contained in a housing 31 defining a 
cooling chamber 30. 
The hot strip 100 is transferred continuously and vertically downwardly in 
FIG. 13 by means of drive rollers 50 so as to be subjected to a 
predetermined cooling process. 
The gas-liquid jet units 40 are arranged in a plurality of layers and are 
supported by brackets 41 so as to face the front and rear surfaces (both 
sides) of the strip 100 with a predetermined spacing from the latter. The 
units 40 on one side of the strip are vertically offset from those on the 
opposite side. At the lower portion of the housing 31 there are provided 
liquid drain ports 44 which are beneath the rear ends of units 40, i.e. 
ends remote from strip 100. On the both sides of the housing 31, there are 
provided gas exhaust ports 45. 
According to the present invention, a desired number of water sprays 38 are 
provided along the direction of the movement of the strip 100 on both 
sides of the strip 100 at a predetermined spacing from the latter to blow 
off the water remaining on the strip 100. Since the strip 100 is subject 
to the water pressure of the water sprays 38, guide rollers 37 are 
provided to prevent deflections of the strip 100. 
Also, on both sides of the strip 100 are provided gas jet means 36 for 
finally removing the water which may remain on the strip 100 in spite of 
the operation of the water sprays 38. 
With the above structure, when a high speed gas-liquid jet is applied to 
the hot strip 100, it is reflected upwardly and the greater part of liquid 
separated from the gas-liquid jet is received by the plate 22 which is 
inclined rearwardly and downwardly and at the same time guided to flow 
away from the hot strip so as to be collected at the exhaust ports 44 
through which it is discharged. The numeral 42(FIG. 13) designates posts 
to support the brackets 41. 
Similarly, gas (e.g. N.sub.2 gas) separated from the gas-liquid jet is 
collected through the exhaust port 45. 
Water remaining on or adhered to the surfaces of the strip 100 is also 
discharged through the drain ports 44 after it is removed from those 
surfaces by means of the water sprays 38. 
Likewise, water removed by the gas jet means 36 is discharged through the 
drain ports 44 while used gas is discharged through the exhaust ports 45 
and is collected as required. 
In the cooling chamber 30, there can be provided a suitable number of the 
water sprays 38 so that the water remaining on the strip 100 is easily 
removed from the strip at suitable positions thereof. 
One example of such water sprays 38 is illustrated in FIGS. 14 and 15, each 
comprising spray nozzles 38A and a common main water feed pipe 38B which 
extends in the direction of the width of the strip 100. Each of the spray 
nozzles 38A removes the water remaining on the strip surfaces in the 
direction of the width of the strip by causing the spray of water 
therefrom intersect with that from the adjacent nozzle, so that it serves 
as a so-called water-knife. 
Although the nozzles 38A have curved front ends, in the illustrated 
example, they may, of course, have straight front ends. 
Further, the above described gas jet means 36 are provided within the 
cooling chamber 30 at a position near the outlet for the strip 100 so that 
the water remaining on the strip 100 can be easily removed by the gas jets 
(e.g. N.sub.2 gas) without the strip's carrying such water thereon when it 
is transferred to the succeeding step. 
Thus, according to the present invention, it is possible to remove without 
fail the water remaining on the strip, and, therefore the problem of 
indirect cooling arising from such water can be neglected and a desired 
final temperature can be given to the strip. 
Further, where the gas-water jet units in a plurality of stages are 
arranged close to the strip, the strip passing through the clearance 
between the opposing rows of the gas-liquid jet units is liable to be 
deflected in proportion to its length and to prevent this, the guide 
rollers 37 are arranged at suitable positions. 
These guide rollers 37 serve to restrict the rattling and twisting of the 
strip to a minimum which results in reducing the danger of the strip 
coming into contact with the gas-liquid jet units, the water sprays or the 
gas jet means. 
Thus, according to the present invention, the greater part of the liquid 
used in cooling by the gas-liquid jet unit or units is carried away 
quickly and positively and, accordingly, an atmosphere suitable for 
effective cooling and its control is produced. 
While the present invention has been described with reference, in the main, 
to a cooling apparatus incorporating multistaged gas-liquid jet units 
inclined at an angle of inclination of .alpha., it will be obvious that 
the present invention is not limited thereto and changes and modifications 
thereof may fall within the scope of the present invention unless they 
contradict the purposes of the present invention.