JPH069687Y2 - Descaling device with water hammer prevention - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement of a descaling device incorporated in a hot rolling facility. In particular, the present invention relates to a water hammer-preventing descaling device suitable for rolling a stainless slab by a reversal system rolling device to manufacture a thin stainless plate.

[Conventional technology]

As is well known, the descaling device incorporated in the rolling equipment uses high-pressure water (150 to 200 kg / c) on the slab flowing from the rolling process, that is, on the upper and lower surfaces of the rolled material.
m ² ) for injecting and performing descaling.

Therefore, the nozzle header in the descaling device is connected to a water supply line that supplies high-pressure water by two upper and lower parts via branch pipes, and the two upper and lower nozzle headers are connected to the high-pressure water called a descaling nozzle at a constant pitch. In general, a plurality of injection nozzles are provided.

That is, a mechanism for passing a slab between the upper and lower nozzle headers having a plurality of descaling nozzles, and in the process of passing the slab, high-pressure water is uniformly sprayed from both sides of the slab to perform descaling. Is generally.

By the way, the slab to be subjected to this descaling, that is, a rolled material is usually intermittently sent out through a rolling roll. Therefore, the descaling device is also configured to be operated intermittently according to the flow of the rolled material.

Therefore, the nozzle header is repeatedly subjected to a load (on-load) state in which high-pressure water flows and a no-load (unload) state in which high-pressure water is stopped.

As a result, there is a problem that when the unloading state is switched to the on-loading state, a water hammer phenomenon (water hammering) occurs in the nozzle header. That is, during unloading, air enters the nozzle header from the descaling nozzle, and the invading air is abruptly pressed at the moment when it is switched to on-load, causing a sudden change in pressure and causing a so-called water hammer phenomenon. It was the cause.

Therefore, as a means for suppressing the occurrence of this water hammer phenomenon, the following method has been used so far to block the intrusion of air from the descaling nozzle into the nozzle header.

(1) High Pressure Water Bypass Method This method is a high pressure water feed line 3 for feeding high pressure water to an upper nozzle header 2a and a lower nozzle header 2b having a plurality of descaling nozzles 1 as shown in FIG.
The bypass line 3a is provided in the
This is a method in which an appropriate amount of high-pressure water, that is, an amount of water that does not allow air to enter the upper nozzle header 2a and the lower nozzle header 2b, is constantly flowed through the a during unloading.

Specifically, during unloading, the upper and lower nozzle headers 2a and 2b are connected via the bypass line 3a.
The high-pressure water is sent to the above, and the high-pressure water is discharged from each of the descaling nozzles 1 to prevent the invasion of air.

In this figure, reference numeral 4 provided in the water supply line 3 is an electromagnetic on-off control valve for switching the high pressure water to the upper nozzle header 2a and the lower nozzle header 2b according to on-load and unload and sending the water. , A so-called switching control valve. Further, 5 provided in the bypass line 3a is an orifice for adjusting the amount of water for sending an appropriate amount of high pressure water to the upper nozzle header 2a and the lower nozzle header 2b during unloading.

(2) Low Pressure Water Injection Method This method is the most widely used method, and as shown in FIG. 7, low pressure water ( ^{2 to 3} kg / cm ² ) is supplied to the upper nozzle header 2a and the lower nozzle header 2b. Water line 6
The low pressure water is sent through the water supply line 6 to the upper nozzle header 2a and the lower nozzle header 2b side during the unloading in the same manner as in the bypass method to prevent the invasion of air.

The check valve 8 provided on the water supply line 6 in this figure is
Reference numeral 9 is a high-pressure water sluice valve, 10 is a safety valve, and 11 is a low-pressure water injection source valve.

(3) Pilot nozzle check valve method In this method, each descaling nozzle 1 has a built-in check valve, and when unloading, this check valve (not shown) is activated to prevent air from entering. is there.

However, in this method, since the check valve is built in the descaling nozzle 1 itself, that is, the check valve is installed in the nozzle through which high-pressure, high-velocity water flows, the structure becomes complicated and the operation is difficult. Due to the fact that it is exposed to extremely harsh conditions, it is difficult to maintain its durability, and it has not yet become widespread as an actual device.

Therefore, the most popular methods at present are the second low-pressure water injection method and the first high-pressure water bypass method.

[Technical issues to be solved by the invention]

By the way, the conventional method for suppressing the water hammer phenomenon, that is, the descaling apparatus incorporating the first and second methods has the following two major problems.

(1) Problems in equipment First, in the descaling equipment incorporating the first method for suppressing the water hammer phenomenon by the high-pressure water bypass method, the bypass is performed while the descaling work is not performed, that is, during the unloading time. 150-200kg via line 3a
Since the high-pressure water of / cm ² is discharged from the descaling nozzles 1 ... Of the nozzle headers 2a and 2b, there is a disadvantage that the energy consumed during that time is large and the operating cost becomes high. In some cases, there is a case in which the size of the pump for producing the high-pressure water must be increased, which causes a problem in the economical efficiency of the device.

The second low-pressure water injection method is also similar to the high-pressure water bypass method.
While the descaling work is stopped, that is, while unloading,
Since it is a method of discharging low-pressure water, there is a drawback in that it is not economical in terms of water consumption.

Further, as shown in FIG. 7, since the low-pressure water supply line 6 is connected to the high-pressure water supply line 3, the high-pressure water is supplied at the moment when the unloading is switched to the on-load, that is, when the descaling is started. However, there is a problem that the water flows back to the side of the low pressure water supply line 6. Therefore, in order to prevent this backflow, the low pressure water supply line 6
In addition, it is necessary to provide a check valve 8 as shown in FIG. 7, a sluice valve 9 for high pressure water, a safety valve 10 and the like, which causes a cost increase of the device.

In addition, since these various valves must be operated in a timely manner in response to switching between on-load and unload, there has been a troublesome operation control.

Also, when switched from unload to on-road,
That is, high pressure water is supplied to the upper and lower nozzle headers 2a, 2
At the moment when sending to b side and starting descaling work,
The flow of water in the low-pressure side water supply line 6 is suddenly stopped, and in some cases, a water hammer phenomenon occurs on the water supply line 6 side with the sudden stop of the flow.

(2) Problems in rolling equipment of reversal system Even if the descaling equipment has the above-mentioned equipment problems, if this is incorporated in the rolling equipment of a straight line, mainly water loss, The above-mentioned problems with the device from the viewpoint of operational safety and maintenance were only pointed out.

However, this is a rolling facility that uses a reversal system,
In particular, when it was installed in a rolling facility for manufacturing thin stainless steel plates, there were the following major problems in terms of maintaining product quality and operation.

As is well known, in rolling equipment that employs a reversal system, rolling material that has once passed through rolling rolls is returned, and the rolled material is fed back to the rolling roll side. It is to do work.

On the other hand, the descaling work, which differs depending on the steel type of the rolled material, is basically performed only once just before passing the rolling roll for the first time. That is, the rolling process without descaling is continued from the second time. A typical example is rolling a thin stainless steel plate.

However, as described above, in order to suppress the water hammer phenomenon, in the descaling device that employs the high-pressure water bypass method or the low-pressure water injection method, high-pressure water or Low-pressure water is being discharged from the descaling nozzle.

Therefore, in the rolling equipment of the reversal system, the discharged water, especially the water from the upper nozzle header 2a side, falls on the material in the rolling process even during the returning process of the rolled material.

As a result, when rolling a stainless steel sheet,
The material in the process is cooled by the influence of the water. Moreover, it is in the form of being partially cooled.

As a result of the one-sided cooling, there is a problem that not only the product quality varies but also a warp phenomenon occurs due to a temperature change and, in the worst case, a misroll is induced.

In any case, the descaling device in the conventional rolling equipment handles high-pressure water and is used for intermittent switching operation between on-load and unload, so that no water hammer phenomenon occurs. At the time of unloading, it is required to have a structure such that water does not fall on the rolled material flowing in the process. Especially in the case of thin sheet thickness rolling of stainless steel, this is an absolutely necessary item.

The present invention has been made for the purpose of providing a descaling device that can meet such demands.

[Means for Solving the Problems]

As a means for achieving the above-mentioned object, the present invention connects an upper nozzle header and a lower nozzle header having descaling nozzles attached at a constant pitch to a high-pressure water supply line,
In a descaling device configured to insert a slab between the upper nozzle header and the lower nozzle header, and to perform descaling on both surfaces of the slab by injecting high-pressure water from the descaling nozzle when the slab passes through, The descaling nozzle attached to the upper nozzle header is attached to a header pipe forming the upper nozzle header via an inner pipe inserted in the header pipe, and the upper nozzle header and the high pressure water supply line are connected. The rising pipe has a check valve with a built-in return spring.

Further, the gap l ₂ between the upper end opening of the inner pipe inserted into the header pipe and the inner peripheral wall of the header pipe is set to be as narrow as possible in consideration of pressure loss.

Further, on the wall surface corresponding to the ceiling of the header pipe inner peripheral wall between the nozzle and the descaling nozzle attached to the header pipe via the inner pipe, a crescent-shaped spacer is lined to form an air space in the header pipe. Is set to the minimum.

[Action]

Since the descaling device with water hammer prevention according to the present invention is configured as described above, the descaling device with the upper nozzle header is normally operated during on-road, that is, during the descaling work by injecting high-pressure water. High-pressure water is sent to the header side through a check valve that has a built-in return spring provided in a rising pipe that connects the high-pressure water supply line.

Then, high-pressure water is jetted from the descaling nozzle attached to the upper nozzle header, and an appropriate descaling operation is performed.

Therefore, when the descaling work is stopped and the high-pressure water injection is stopped, that is, when the on-load is switched to the unload, the water in the upper nozzle header, that is, the nozzle, inner pipe, and crescent-shaped spacer Partial water is discharged to the outside and replaced by air. However, due to the check valve provided in the rising pipe, the remaining water is retained in the header pipe that constitutes the upper nozzle header. As a result, outside air does not enter the header pipe through the descaling nozzle during unloading.

Since outside air does not enter, water hammer does not occur at the time of switching to on-road.

〔Example〕

Further, the configuration of the present invention will be specifically described with reference to the drawings showing an embodiment.

First, FIG. 1 is a partially cutaway front view showing a mounting portion of an upper nozzle header A and a lower nozzle header B in a descaling device. Descaling nozzles 20 are attached to the upper nozzle header A and the lower nozzle header B at a constant pitch.

Then, the upper nozzle header A and the lower nozzle header B
High-pressure water is jetted to the slab C passing between
It is configured to do the appropriate descaling. The high-pressure water for the upper nozzle header A is fed through a rising pipe 22a in a branch pipe 22 connected to a high-pressure water feed line 21 as shown in the piping system diagram of FIG. A check valve 23 is provided in the middle of the rising pipe 22a.

FIG. 3 is a front view showing a part of the upper nozzle header A connected to the rising pipe 22a in a cutaway manner.

As shown in the figure, the upper nozzle header A is composed of a header pipe 24 and the descaling nozzles 20 ... Attached to the header pipe 24 at a constant pitch, and the left side thereof is the piping system diagram of FIG. As shown, it is connected to the rising pipe 22a of the branch pipe 22 connected to the high-pressure water supply line 21.

Next, the descaling nozzle 20 for the header pipe 24 is attached downward, and in the embodiment, as shown in FIG.
Six of them are attached at intervals of 6 mm.

FIG. 4 is a vertical cross-sectional side view showing the mounting portion of the descaling nozzle 20 to the header pipe 24 in an enlarged manner.

As shown in the figure, the descaling nozzle 20 is fixed to the outer periphery of the lower surface of the header pipe 24 by welding means via an inner pipe 25 inserted into the header pipe 24. At this time, the jetting angle of the descaling nozzle 20 is set so as to be inclined downward about 15 degrees with respect to the vertical line orthogonal to the axis of the header pipe 24.

The inner pipe 25 is attached so that its upper end opening 25a corresponds vertically to the inner peripheral wall 24a of the header pipe 24. That is, the inner peripheral wall 2 of the header pipe 24
It is attached so as to face the ceiling side of 4a.

The gap l ₂ between the upper end opening 25a of the inner pipe 25 and the inner peripheral wall 24a of the header pipe 24 is set as narrow as possible in consideration of the pressure loss when high-pressure water passes through.

Incidentally, in the embodiment, as described above, the 3B size header pipe 24 is used, and l ₂ is set to 6 mm. Therefore, the water is sprayed downward from the descaling nozzle 20 through the gap of 6 mm at an angle of 15 °.

FIG. 5 shows a header pipe 2 which constitutes the upper nozzle header A.
4, the inner peripheral wall 24 of the header pipe 24 between the descaling nozzles 20 and 20 mounted at a constant pitch.
It is a perspective view of the principal part which shows the attachment point of the crescent-shaped spacer 26 lined in a.

As already mentioned, this crescent spacer 26
This is for keeping the air space in the header pipe 24 to a minimum. In the embodiment, as shown in FIG. 3, l ₂ ≈56 mm is provided between the descaling nozzles 20 mounted at a pitch of 136 mm. It is installed in the way that it is lined with a space between.

Next, the upper nozzle header A and the high pressure water supply line 22
Check valve 23 provided in the middle of the rising pipe 22a connecting to
As shown in FIG. 1, a check valve incorporating a spring 23a and a return spring formed by pressing the valve body 23b downward by the spring 23a is used. 23c is a spring retainer.

The water hammer prevention descaling device according to the present invention is configured as described in detail based on the above embodiments, and therefore, during the descaling work, that is, during the on-load, as shown in FIG. The high-pressure water is supplied to the upper nozzle header A via the check valve 23 provided in the middle of the rising pipe 22a. At the same time, the high pressure water is supplied to the lower nozzle header B as well.

Then, the supplied high-pressure water is sprayed from the descaling nozzles 20 attached to the upper nozzle header A and the lower nozzle header B, respectively, to the slab C passing between them, and an appropriate descaling work is performed. become.

Then, when the supply of high-pressure water is stopped and the operation is switched to unloading, the water fed to the upper nozzle header A side can be backflowed by the action of the check valve 23 provided in the rising pipe 22a. It is not discharged to the outside from the descaling nozzles 20 ... Attached to the nozzle header A.

That is, the header pipe 2 that constitutes the upper nozzle header A
The water in 4 is reserved. Check valve 23
Since the valve body 23b is pressed by the return spring composed of the spring 23a, the electromagnetic on-off control valve provided in the high-pressure water supply line 21 as shown in FIG. Even if the high-pressure water leaks to some extent in the closed state due to aging, the water does not drip from the upper nozzle header A.

Moreover, the descaling nozzles 20 ... Attached to the header pipe 24 are attached via the inner pipe 25, and the descaling nozzles 20 and 20 are further attached.
Between the header pipe 24 and the inner peripheral wall ceiling portion of the header pipe 24, a spacer 26 having a crescent shape is attached so as not to form an air space in the header pipe 24. Even if the operation, that is, the on-road state is switched to and the high-pressure water is momentarily fed into the header pipe 24, so-called water hammer does not occur.

[Effect of device]

As described above, when the load is switched from the on-load to the unload as described above, the water is retained inside the upper nozzle header through the check valve and is retained inside the header. Since the device is devised so that it does not accumulate, the following effects can be achieved as compared with conventional descaling devices that incorporate the high-pressure water bypass method, low-pressure water injection method, and the like.

(1) There is no need to run water during unloading to prevent water hammer. Therefore, it is not necessary to install a special bypass line in the device itself, a low-pressure water supply line, or other auxiliary parts for safety maintenance. As a result, the cost of the device is reduced,
And the energy saving effect is produced.

(2) Because water is not released when unloading,
It can also be installed in rolling equipment that uses a reversal system. That is, water does not fall on the material during the pullback process of the rolled material. As a result, it is possible to manufacture a thin plate material made of a material such as stainless steel whose temperature is strictly controlled during rolling.

[Brief description of drawings]

The drawings show an embodiment of a descaling device with water hammer prevention according to the present invention. FIG. 1 is a partially cutaway front view showing a mounting portion of an upper nozzle header and a lower nozzle header, and FIG. It is a piping system diagram. FIG. 3 is a partially cutaway front view of the upper nozzle header, and FIG. 4 is an enlarged vertical side view showing a mounting portion of a descaling nozzle to a header pipe forming the upper nozzle header.
The drawing is a perspective view of a main portion showing a procedure for attaching the spacer to the header pipe. Note that FIG. 6 is a piping system diagram of a conventional descaling device for preventing water hammer by the high pressure water bypass method, and FIG. 7 is a piping system diagram of the same low pressure water injection method. A ... Upper nozzle header B ... Lower nozzle header 20 ... Descaling nozzle 21 ... High-pressure water supply line 22 ... Branch pipe 22a ... Rise pipe 23 ... Check valve, 23a ... Spring 23b ... Valve body 23c ... Spring retainer 24 ... Header pipe 24a ... Inner peripheral wall of header pipe 25 ... Inner pipe 25a ... Upper end opening of inner pipe 26 ... March shaped spacer

Claims (3)

[Scope of utility model registration request] 1. An upper nozzle header and a lower nozzle header having descaling nozzles attached at a fixed pitch are connected to a high-pressure water supply line, and a slab is inserted between the upper nozzle header and the lower nozzle header, and the slab is inserted. In the descaling device configured to spray high-pressure water from the descaling nozzle to descale both sides of the slab when passing, the descaling nozzle attached to the upper nozzle header constitutes an upper nozzle header. A water hammer which is attached to a header pipe via an inner pipe inserted into the header pipe, and a check valve is provided on a rising pipe connecting the upper nozzle header and a high-pressure water feed line. Descaling device with prevention. _2. A gap ₂ between an upper end opening of an inner pipe inserted into the header pipe and an inner peripheral wall of the header pipe.
The water hammer prevention descaling device according to claim 1, characterized in that the pressure is set as narrow as possible in consideration of the pressure loss. 3. A header having a crescent spacer is lined on the wall surface corresponding to the ceiling of the inner peripheral wall of the header pipe between the nozzle and the descaling nozzle attached to the header pipe via the inner pipe. The air space in the pipe is set to a minimum value.
Descaling device with water hammer prevention according to (1) and (2).