JPH0623607U - Cooling nozzle header - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a cooling nozzle header that requires less installation space, has no variation in cooling water in the longitudinal direction of the header, and has excellent draining responsiveness. [Structure] A lower header 3 having a structure in which one end side of a horizontal long cylinder is liquid-tightly closed and cooling water is supplied from the other end side, and a plurality of long cylinder-shaped upper headers 1 closed at both end sides are connected to each other. A rectifying plate 11 was provided on the upper nozzle header 1 of the nozzle header having a number of hairpin type nozzles 10 connected by a pipe 2 and fixed near the top of the upper header 1. In addition, for the purpose of improving drainage, the upper nozzle header 1
A plurality of air bleeders 14 that are in communication with
Is provided and communicated with these air vent pipes 14, and an exhaust pipe 15 is provided at a position higher than the water supply column.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a nozzle header in a cooling device for hot rolled steel sheets and the like.

[0002]

[Prior art]

 As is well known, a steel plate or the like finish-rolled in a hot rolling step is continuously cooled by receiving a cooling water jet from a cooling nozzle header and then wound. This cooling is usually performed by jetting cooling water onto the steel plate surface from a number of nozzles provided on a header that is arranged above the continuously moving steel plate and in a direction orthogonal to the steel plate transport direction. .

Conventionally, the most common cooling device is a header having a so-called hairpin-shaped nozzle, and the shape thereof is as shown in FIGS. 12 and 13.

In both figures, reference numeral 100 denotes a cylindrical header body, to which high-pressure cooling water is supplied from one side thereof. Reference numeral 101 denotes a hairpin-shaped (in other words, siphon-shaped) nozzle group which is communicated with the inside of the header body 100 and is provided on the upper side of the nozzle body 101. 102, 102 is set to the top position. The cooling water W from the header body 100 is configured to be jetted orthogonally to the upper surface of the lower steel plate S through the nozzles 101, 101 ...

Since the header body 100 has a structure in which water is supplied from one side, the water pressure on the water supply side in the longitudinal direction of the header body 100 is high and the water pressure on the non-water supply side is low. Therefore, the amount of water jetted from the nozzle 101 is also non-uniform in the longitudinal direction accordingly.

Further, when a cooling stop command is issued, the outflow of cooling water from the nozzles 101, 101 ... Group in the longitudinal direction needs to be stopped instantaneously, but with the structure of the above header, the supply of cooling water is stopped. After that, for a certain period of time, residual water is sucked up from the header body 100 due to the siphon phenomenon, and the water tends to continue to drop from several or more nozzles.

This phenomenon makes the injection amount of the cooling water non-uniform, causes variations in the temperature of the steel sheet in the width direction and the length direction, and causes non-uniformity of the material of the steel sheet.

In order to solve these problems, for example, there is a nozzle header described in Japanese Utility Model Laid-Open No. Sho 63-2 7849. In this header, as shown in FIG. 14, instead of supplying water from one end of the header body 201 in the longitudinal direction, a plurality of water supply pipes 200 are provided at intervals in the longitudinal direction, and in order to improve drainability, the hairpin nozzle is not used. Instead, it uses a straight nozzle 202.

Further, as shown in FIGS. 15 and 16, the structure of this nozzle header is such that the straight nozzle 202 is fixed by penetrating the header body 201, and the roof-shaped upper header 203 is fixed to the header body 201. Liquid-tightly fixed to the upper part of the head header 203, and the upper header 203 of the head body 201 is further provided with a crocodile hole 204.

In this nozzle header, the cooling water W is introduced into the water supply pipe 200 by the pump 205 and enters the header body 201. This cooling water enters the space between the upper header 203 and the header body 201 through the through hole 204, is then press-fitted into the nozzle 202, drops downward, and is jetted onto the steel plate surface S. Has become.

[0011]

[Problems to be solved by the device]

 However, in the nozzle header described in the above publication, the inner wall dimensional accuracy of the upper header 203 and the chamfering processing accuracy of the upper end of the nozzle 202 are likely to vary, and when welding the upper header and the header body, in the header longitudinal direction. It becomes difficult to generate deformation and make the jet of cooling water uniform. Moreover, as shown in FIG. 14, since a plurality of water supply pipes 200, 200 ... Are provided at intervals in the direction along the head body 201, it is necessary to secure a long space in the conveying direction of the steel plate S. For this reason, when a plurality of headers are arranged in the transport direction of the steel sheet S, the gap between the adjacent headers is too wide, and the cooling capacity is lowered.

Further, even when draining water, the water does not stop falling until all the water remaining in the upper header 203 is discharged from the nozzle 202, so the responsiveness at the time of stoppage is poor and the cooling of the steel sheet is completed. The temperature cannot be controlled accurately.

The above-mentioned problem of space is solved in the example shown in FIG. 1 of Japanese Utility Model Publication No. 63-44168, but the above-mentioned other problems still remain.

Therefore, the problem of the present invention is that there is no problem of installation space, there is no variation in cooling water in the longitudinal direction of the header, the water flow is stable even when the amount of supplied water changes, and the draining response is good. To provide a simple cooling nozzle header. It also aims to provide a cooling nozzle header that further improves water flow stability and drainage response when there is room in the installation space.

[0015]

[Means for Solving the Problems]

 The above problem is, as a first example, a cylindrical lower header having a structure in which the shaft center is arranged substantially horizontally, one end side is liquid-tightly closed, and cooling water is supplied from the other end side. , Parallel to this, a cylindrical upper header with both ends closed, a plurality of communicating pipes that connect the lower header and the upper header at intervals in the axial direction, and the upper header in the axial direction. A plurality of nozzles spaced apart from each other, a part of each nozzle rises from the upper header and a discharge port of the cooling water faces downward, and a flow resistance means is provided at a communicating portion by each communicating pipe. This can be solved by increasing the flow resistance between the cooling water supply side and the closed side on the water supply side. In addition, as a second example, a substantially horizontal straightening plate having a large number of through holes is provided in the upper header so as to be divided into upper and lower parts, and the diameter of the through holes of the straightening plate is closed from one end side which constitutes the water supply side. One end may be smaller between the other end forming the side and the other end.

Further, in this second example, the space between the top end of the upper header and the current plate is partitioned within the upper header and above the current plate to have a uniform diameter. It is desirable to provide another substantially horizontal straightening vane having a large number of through holes. In contrast to the first example and the second example, as a third example of the present invention, a plurality of air bleeding pipes are provided in communication with the upper header and spaced in the longitudinal direction. It is possible to provide a common exhaust pipe that communicates with the drain pipe and is higher than the water supply column.

[0017]

[Action]

 In each of the examples of the present invention, since water is supplied from one side of the lower header, the space in the flow direction of the steel plate does not matter. Moreover, even if water is supplied from one side of the lower header, in the first example, a flow resistance means is provided at the communication portion of each communication pipe with the upper header, and the resistance of the flow is the cooling resistance. Since the water is larger between the water supply side and the closed side on the water supply side, the discharge flow rate from each nozzle group can be made uniform by adjusting or setting the flow resistance.

In the present invention, it is desirable to use, for example, a hairpin type nozzle in which a part of each nozzle rises from the upper header and a cooling water discharge port faces downward. When this hairpin type nozzle is used, a plurality of air supply ports are formed in the longitudinal direction so as to communicate with the upper header, as will be described with reference to the first example below, and a common air supply port for these air supply ports is formed. By connecting the trachea and supplying compressed air through the air supply pipes at the same time when the water supply is stopped, the residual water in each nozzle can be discharged at once, resulting in excellent drainage.

In the first example, if the upper nozzle header is provided with a straightening vane that divides the upper and lower parts and has a large number of through holes, it has an effect of making the discharge flow rate from each nozzle more uniform. When a current plate is provided in the middle of the upper header to substantially partition the inside of the upper header, the upper space becomes smaller, and as a result, when compressed air is supplied from the air pipe, a small volume of water is generated. On the other hand, since compressed air is applied, the drainage property is further improved.

On the other hand, in the first example, the distribution of the water supply pressure is offset by the magnitude of the resistance at the location of the communication pipe. However, it is effective only when the number of communication pipes is large, and therefore not necessarily effective when the number is small. Moreover, when changing the resistance means of the communication pipe by changing the water supply pressure, etc., it is necessary to disassemble the whole.

In order to solve this problem, according to the second embodiment of the present invention, a substantially horizontal straightening plate having a plurality of through holes is provided in the upper header to divide the upper and lower parts from each other. The diameter of the through hole is made smaller toward the one end side between the one end side forming the water supply side and the other end side forming the closing side.

In this second example, the discharge flow rate from each nozzle group is made uniform by adjusting the through hole diameter of the straightening vanes or adjusting the installation position of the straightening vanes in the upper head. You can

In the second example, in addition to the rectifying plate, a second rectifying plate having a large number of through holes each having a uniform diameter and a uniform distribution is provided above the rectifying plate. There is an advantage that the discharge flow rate from the nozzle group can be made more uniform.

On the other hand, also in the second example, the hairpin type nozzle described above can be used, and a common air supply pipe can be attached.

In any case, when using the hairpin type nozzle, there remains a problem to be solved. That is, as shown as a second example below, if the rising height of the nozzle is suppressed as much as possible and the top end of the upper header is slightly raised (specifically, about 20 to 30 mm), the drainage property is reduced. However, the water flow from the nozzle is not stable due to the problem that the water injection from the nozzle is interrupted when the amount of supplied water changes.

Therefore, when the rising height of the nozzle is set to a position higher than the top end of the upper header (specifically, about 200 to 300 mm), the water flow is stable, but the siphon effect works greatly and the drainage property is extremely high. Worsens.

Therefore, according to a third example of the present invention, a plurality of air vent pipes are provided at intervals in the longitudinal direction so as to communicate with the upper header, communicate with each of these air vent pipes, and It is preferable to provide an exhaust pipe that is open to the atmosphere at a high level.

As a result, when the water supply is stopped, the intruding air from the nozzle end escapes to the exhaust pipe through the air bleeding pipe to cancel the siphon phenomenon, and as a result, the drainage property becomes good.

[0029]

【Example】

 Next, the present invention will be specifically described with reference to examples. 1 is a front view showing a cooling nozzle header of a first example according to the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a view taken along line 3-3 thereof.

On the other hand, FIG. 4 is a front view showing a cooling nozzle header of a second example according to the present invention, FIG. 5 is a side view thereof, FIG. 6 is a view taken along line 6-6 thereof, and FIG. FIG. 11 is a plan view showing a first punching metal for adjusting distribution, and FIG. 11 is a plan view showing a second punching metal for rectifying.

On the other hand, FIG. 7 is a front view showing another example of the cooling nozzle header according to the present invention, FIG. 8 is a side view thereof, and FIG. 9 is a view on arrow 9-9.

First, the first example will be described. The nozzle header according to the present invention basically comprises a horizontally arranged upper header 1 having a long tube shape with both ends closed, and a plurality of communication tubes 2 attached thereto. It is provided with an upper header 1 and a parallel lower header 3 which are connected in communication with each other. The cooling water W is configured to be supplied only from one side of the lower header 3 (direction of arrow in FIG. 1). ing.

Hairpin-shaped (inverted J-shaped) nozzle tubes 10, 10 ... Are provided on the upper part of the upper header 1 so as to project on both sides in a communicating state. A large number of these nozzle tubes 10 are provided in the width direction of the steel plate. Has been. Further, this arrangement is similar to the example shown in FIG.

A closing plate 30 is liquid-tightly closed at one end of the lower header 3 by bolting. With this structure, the closing plate 30 is removed so that the inside of the lower header 3 can be easily cleaned. The other end of the lower header 3 is connected to a water supply pipe (not shown), and the cooling water W is supplied into the lower header 3 from here.

As described above, the lower header 3 and the upper header 1 are connected to each other by a plurality of communication pipes 2 arranged at intervals in the width direction of the steel plate, and the cooling water W supplied into the lower header 3 is Water can be supplied to the upper header 1. It is preferable that the number of communication pipes 2 is about six. Each of these communication pipes 2 has a connecting portion formed by bolting two flanges 20 facing each other at an intermediate portion thereof, and an orifice plate 21 is inserted into the flange portion.

The orifice plate 21 is selected and installed such that the closer it is to the water supply side in the longitudinal direction of the lower header 3, the larger the throttle amount (the smaller the orifice diameter) becomes. Since the water pressure is higher as it gets closer to the water supply side, the flow rate to the upper header will increase as it gets closer to the water supply side, and the amount of water ejected from the nozzle pipe will be uneven, if the flow rate adjustment orifice is not installed. This is because effective cooling is impossible.

Next, the specific structure of the upper header 1 will be described. As described above, both end sides of the upper header are provided with flanges like the closed ends of the lower header 3 and the closing plate 31 is bolted thereto. It is liquid tightly closed. A hairpin type nozzle tube 10 is provided near the upper end of the upper header 1 at longitudinally symmetrical positions. The rising position of the nozzle tube 10 is, for example, about 10 to 20 mm higher than the top end of the upper header 1, and a straight tube part of about 300 mm is provided downward to improve the formation of laminar flow. Therefore, since the lower header 3 can be installed in the space between the straight pipe portions of the two hairpin type nozzles, the installation space of the entire nozzle header can be made compact even though the header has a two-tier structure.

A punching metal (porous rectifying plate) 11 is horizontally installed in the upper header 1 over the entire length in the longitudinal direction. As a specific example of the punching metal 11, the punching metal 11 shown in FIG. 11 can be mentioned. By mounting the punching metal 11, the water supplied from the lower header 3 is supplied to the hairpin type nozzle pipe 10 in a state where the pressure is further equalized and a laminar flow is generated. Therefore, there is no difference in the flow rate between the nozzle tubes 10 in the longitudinal direction of the header, the flow rate distribution is made uniform, and more uniform cooling is possible in combination with the installation of the orifice described above.

Further, a plurality of air supply ports 13 (for example, 10 to 12 places) are provided at the upper end of the upper header 1, and an air supply pipe 12 for sending compressed air is connected to each of the air supply ports. A valve (not shown) is attached to the bottom of the air supply pipe 12. This valve is designed to open simultaneously with the header water supply valve when it is closed. Therefore, at the same time as the header water supply is stopped, compressed air is sent from the punching metal in the upper header 1 into the upper half space. In this case, since the punching metal 11 is installed, the compressed air impinges on the upper surface of the punching metal 11 and the reaction force causes the air pressure to forcibly discharge the residual water in the hairpin type nozzle tube 10. It works in the direction of doing so and can improve the draining responsiveness.

At this time, the air consumption amount can be reduced and the cost can be reduced by lowering the rising portion of the hairpin type nozzle tube 10 or by setting the mounting position of the punching metal 11 to a higher position. Good.

In the above example, the communication pipe is provided with an orifice plate to adjust the flow resistance. However, for example, a flow rate adjusting valve is provided to adjust the opening of each flow rate adjusting valve in advance or each time. By doing so, the flow resistance may be adjusted. The flow resistance means may be provided in the middle of the lower header 3 to the upper header 1 or at the entrance / exit.

Next, the second invention, which is effective for a nozzle header having a small number of communicating pipes 2, will be described. In the upper header 1, a substantially horizontal punching metal 11A having upper and lower partitions and a large number of through holes is provided. It is provided. That is, the first punching metal 11A for horizontally adjusting the water amount distribution is attached horizontally over the entire length in the longitudinal direction in the upper header 1 at, for example, a 1/4 lower position, and further in parallel with the first punching metal 11A. A second punching metal 11B for rectification is mounted at a position above, for example, the central position.

As shown in FIG. 10, the first punching metal 11A has a large number of through holes 11a, and the diameter of the through holes 11a is close to the water supply side (right direction in FIGS. 4 and 10). Has been made smaller. This is because the water pressure increases as it gets closer to the water supply side, so if the diameter of the through hole is uniform in the longitudinal direction, the nozzle pipe 10 closer to the water supply side has a larger amount of water ejected from it. As a result, the amount of water jetted from each nozzle pipe 10, 10 ... Will vary, making it impossible to uniformly cool the steel sheet in the width direction. On the other hand, as shown in FIG. 10, when the diameter of each through hole 11a is made smaller so that it becomes closer to the water supply side, when the through hole diameter is small, the resistance is large, the permeation flow rate is small, and the large through hole diameter is large. In this case, since the resistance is small and the permeation flow rate is large, the fact that the water pressure is larger toward the water supply side is offset, and as a result, the amount of water ejected from each nozzle pipe 10, 10 ... Can be made uniform. it can.

On the other hand, the second punching metal 11B has a large number of through holes 11b having a uniform diameter as shown in FIG. The second punching metal 11B can be attached together with the first punching metal 11A by being sandwiched between the mounting seats 31a on the inner surfaces of the closing plates 31, 31 at both ends. By providing this second punching metal 11B, there is no difference in the flow rate between the hairpin type nozzle tubes 10 while the water supply pressure from the lower header 3 is further equalized, and the flow rate distribution is made uniform. In addition to the first punching metal 11A, more uniform cooling can be achieved.

At this time, the punching metals 11A and B can be easily taken out by removing the closing plates 31 and 31 provided at both ends of the upper header 1 by bolt fastening.

Therefore, the punching metals 11A and 11B can be easily cleaned, and further, the inside of the upper header can be easily cleaned.

Next, the third example will be described. In order to obtain the stability of the water flow which is a problem in the first and second examples, the rising position of the nozzle pipe 10 is set to the top end portion of the upper header 1. 200 to 300 mm above. In order to improve the drainage at this time, the upper header 1 is provided with air vent pipes 14, 14 ... And communicates with these air vent pipes, and is a common exhaust pipe 15 which is open to the atmosphere at a position higher than the water supply column. Was set up. As a result, the water-drainability is improved as in Examples described later.

The nozzle tube 10 is preferably a hairpin type, but is not limited to the hairpin type as long as a part of the nozzle rises from the upper header and the cooling water discharge port faces downward. It is not limited that each header is a cylinder.

Example 1 Hereinafter, the effect of the present invention will be clarified by an example. The cooling nozzle header shown in FIG. 4 of the present invention (Example 1), and the double-tube type nozzle header in which the rising portion shown in FIG. 17, which has been generally used conventionally, is located higher than the top end of the upper header ( The flow rate distribution of Comparative Example 1) and the on / off responsiveness due to the supply and stop of cooling water were compared. The nozzle header shown in FIG. 17 has a double pipe structure composed of an inner pipe 300 and an outer pipe 301, and partition members 302, 302 ... Are provided between the inner pipe 300 and the outer pipe 301 at positions separated by 120 °. The high-pressure cooling water that is provided between the inner pipe 300 and the outer pipe 301 flows out through the hairpin-shaped nozzles 303 and 303.

FIG. 18 shows the flow rate distribution of Example 1, and FIG. 19 shows the flow rate distribution of Comparative Example 1. As is clear from FIGS. 18 and 19, in Comparative Example 1, a maximum flow rate difference of about 4 l / min was confirmed, whereas in Example 1, the flow rate was reduced to about 1/3 or less of Comparative Example 1. It was found that the variation can be suppressed, and it is effective for uniformizing the flow rate distribution in the width direction of the steel sheet.

As for the on / off response, as shown in Table 1, in Example 1, the response time was half that of Comparative Example 1, and the response speed could be increased.

[0052]

[Table 1]

Example 2 Next, the effect of the current plate according to the present invention will be clarified. Only the punching metal 11A was attached to the upper header of FIG. 4 and the flow rate distribution in the longitudinal direction of the header was investigated. The result is shown in FIG. Comparing the flow distributions of FIG. 20 and FIG. 18, it is clear that the effect of installing the current plate according to the present invention is remarkable.

Example 3 Next, the effect of the third example of the present invention will be clarified. The nozzle header shown in FIG. 7 according to the present invention was compared with a nozzle header having a nozzle rising height of about 20 to 30 mm shown in FIG. 4, which is a second example of the present invention as a comparative example.

FIG. 21 shows the pressure-flow rate characteristics of the nozzle header of the comparative example. As can be seen from FIG. 21, in the nozzle header of the comparative example, water film breakage occurred in some places, and water flow stability was lacking. On the other hand, the pressure-flow rate characteristic of the nozzle header according to the third example of the present invention is shown in FIG. 22. As can be seen from this figure, even if the flow rate is reduced, film breakage does not occur and the water flow is stable. You can see that Further, it can be seen that the drainage response is also superior to the conventional header by adjusting the pressure in the upper nozzle header as shown in FIG.

[0056]

[Effect of device]

 As described above, according to the present invention, there is no installation space problem, there is no variation in cooling water in the header longitudinal direction, in other words, the discharge flow rate from each nozzle is uniform, and the drainage response is good. There are advantages such as becoming. If there is more space, it is possible to provide a nozzle header that further enhances the above effects.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a nozzle header of a first example according to the present invention.

FIG. 2 is a right side view thereof.

FIG. 3 is a view taken along line 3-3 of FIG.

FIG. 4 is a partially cutaway front view of a second example nozzle header according to the present invention.

FIG. 5 is a right side view thereof.

FIG. 6 is a view taken along the line 6-6.

FIG. 7 is a partially cutaway front view of a nozzle header of a third example according to the present invention.

FIG. 8 is a right side view thereof.

FIG. 9 is a view taken along the line 9-9 of FIG.

FIG. 10 is a plan view of punching metal.

FIG. 11 is a plan view of another punching metal.

FIG. 12 is a side view showing an outline of a conventional nozzle header.

FIG. 13 is a front view of the nozzle header of FIG.

FIG. 14 is a perspective view showing another conventional nozzle header.

15 is a cross-sectional view of the nozzle header of FIG.

16 is a vertical cross-sectional view of the nozzle header of FIG.

FIG. 17 is a cross-sectional view of another conventional nozzle header.

FIG. 18 is a view showing a flow rate distribution of the nozzle header of the present invention.

FIG. 19 is a diagram showing a flow rate distribution of a conventional nozzle header.

20 is a diagram showing a flow rate distribution when the flow straightening plate 11B is not attached to the nozzle header of FIG.

21 is a diagram showing pressure-flow rate characteristics of the nozzle header in FIG.

FIG. 22 is the pressure of the nozzle header of the third example of the present invention;
It is a figure which shows a flow characteristic.

FIG. 23 is a view showing the drainage property of the nozzle header of the third example of the present invention.

[Explanation of symbols]

1 ... Upper header, 2 ... Communication pipe, 3 ... Lower header, 10
… Nozzle tube, 11… Punching metal (porous baffle),
12 ... Air supply pipe, 13 ... Air supply port, 14 ... Air vent pipe, 15 ... Exhaust pipe, 21 ... Orifice, W ... Cooling water, 30 ... Blocking plate.

Claims (5)

[Scope of utility model registration request] 1. A cylindrical lower header having a structure in which a shaft center thereof is arranged substantially horizontally, one end side of which is liquid-tightly closed and cooling water is supplied from the other end side, and a cylindrical lower header which is parallel to this. A cylindrical upper header whose both ends are closed, a plurality of communication pipes which are spaced from each other in the axial direction to connect the lower header and the upper header, and a large number of which are spaced from the upper header in the axial direction. Nozzle of, each nozzle part rises from the upper header and the discharge port of the cooling water is directed downward, has a flow resistance means in the communication portion by each communication pipe, the resistance of the flow is The cooling nozzle header is characterized in that a portion between the cooling water supply side and the closed side is made larger toward a water supply side. 2. A cylindrical lower header having a structure in which a shaft center thereof is arranged substantially horizontally, one end side of which is liquid-tightly closed and cooling water is supplied from the other end side, and a cylindrical lower header which is parallel to this. A cylindrical upper header whose both ends are closed, a plurality of communication pipes which are spaced from each other in the axial direction to connect the lower header and the upper header, and a large number of which are spaced from the upper header in the axial direction. Nozzle of each of the above, a part of each nozzle rises from the upper header and the outlet of the cooling water faces downward, and the upper header is partitioned into a plurality of through holes to divide the upper header into a substantially horizontal straightening A cooling nozzle header, wherein a plate is provided, and a diameter of a through hole of the straightening plate is made smaller toward one end side between one end side forming a water supply side and the other end side forming a closing side. 3. A substantially horizontal surface having a large number of through holes having a uniform diameter in the upper header and at a position above the straightening vane so as to partition a space between the top end of the upper header and the straightening vane. The cooling nozzle header according to claim 2, wherein another current plate is provided. 4. A plurality of air supply ports communicating with the upper header in the longitudinal direction, and a common air supply pipe is connected to the air supply ports. Cooling nozzle header. 5. A plurality of air vent pipes are arranged at intervals in the longitudinal direction so as to communicate with the upper header, and a common exhaust pipe is provided so as to communicate with each of these air vent pipes and at a position higher than the water supply water column. The cooling nozzle header according to claim 1 or 2.