JPS6077932A - Steel cooling apparatus capable of widely controlling flow rate of refrigerant - Google Patents

Abstract

PURPOSE:To control the flow rate of a refrigerant over a wide range by arranging plural groups of nozzles each having a different specified flow rate, and providing simultaneously a cooling controller used solely by each group. CONSTITUTION:The material to be cooled 20 is conveyed by a conveying roll 1 and a presser roll 6 in the direction shown by the arrow. Headers 2A and 2B and 4A and 4B respectively for the lower spray nozzle and for the upper spray nozzle are arranged to the rolls 1 and 6, and nozzle groups 3A, 3B, and 5A, 5B having different flow-rate characteristics are connected to the respective headers. A refrigerant 19 in a water storage tank 18 for the refrigerant is supplied by a pump 17 through a pipe 16 successively into a collecting header, automatic on-off valves 14A, 14B, 15A, and 15B, flow control valves 10A, 10B, 12A, and 12B, flowmeters 11A, 11B, 13A, and 13B, refrigerant supply pipes 7A, 7B, 8A, and 8B, and spouted from the nozzle groups 3A, 3B, 5A, and 5B. The control of the cooling rate is stably carried out by controlling appropriately the amt. of the refrigerant to be spouted.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a cooling device for hot steel sheets installed in a hot rolling line or heat treatment line for steel sheets, and in particular, it is necessary to control the cooling rate over a wide range. Regarding a cooling device.

(Prior art) In recent thick plate manufacturing processes, reduction of alloying elements,
With the aim of omitting heat treatment and developing new steel types, research into the so-called temper cooling process, which combines condolence rolling and immediately followed by forced rolling, has been actively conducted and is already being put into practical use.

The cooling equipment applied to this process must have characteristics that can be adapted to the multi-product production that is a feature of the plate manufacturing process, and must be able to adapt to the various types and sizes of the material to be cooled (particularly the plate thickness). ] In order to ensure the required cooling rate and prevent the occurrence of distortion during cooling, it is necessary to ensure the appropriate cooling rate required by the size of the material to be cooled (plate thickness, plate width) and the upper medium flow rate ratio. In addition, it must have a wide refrigerant flow rate control range.

In contrast, known cooling equipment includes a roller quench as shown in FIG.
There are slit laminar cooling systems as shown in Fig. It only has range. Therefore, these cooling devices are only used for limited purposes.

On the other hand, recently, in order to cover the above drawbacks, for example,
Install the roller quench shown in the figure and the slit laminar cooling device shown in FIG. 4 in series with the laminar cooling device shown in FIG.
f: Depending on each use.

Methods such as using different cooling devices have been proposed, but such methods have drawbacks such as high equipment costs and the need for a large installation space because multiple cooling devices are installed depending on the purpose of use. be.

Conventionally, as a method of controlling the flow rate Q of refrigerant injected from a nozzle, a method of controlling the nozzle back pressure P of the refrigerant has been adopted. That is, between the refrigerant discharge flow rate Q from the nozzle and the nozzle back pressure P of the refrigerant.

There is a relationship of Q=Igu·P1'', which is a value determined by the nozzle model.Now, the nozzle back pressure p f p pr
When changing from ig to P-, the flow rate Q is Q1111
When changing from 41 to Q-1, the relationship from the relationship between P and Q described above is established.

From this, it can be seen that the nozzle back pressure for controlling the cooling flow rate Q must be controlled within the range of α2. Also, in general, in a spray nozzle, the nozzle back pressure P is equal to the flow rate Q.
The impact pressure Pi of cold tofu on the material to be cooled is
and the relationship with the refrigerant spread angle β in the spray nozzle,
They have a relationship as shown in FIG. 6, for example. In addition,
FIG. 7 shows the measuring method shown in FIG. 6, and 21 is a spray nozzle, 22 is a pump, and 23 is a collision pressure detector.

That is, when the nozzle back pressure P of the refrigerant decreases, the refrigerant flow rate Q, the impact pressure P1 on the cooled material to be cooled, and the divergence angle β all decrease.

Among these, the flow rate Q and the collision pressure 1)i are factors that directly affect the cooling capacity, and the spread angle β affects the uniformity of cooling. Therefore, the minimum possible value of the header pressure PO is p m
There is a limit to this, and there are differences depending on the nozzle type, etc., but in the case of spray nozzles, t;zp==05 to 1.
OK9/c#i is the practical limit.

In addition, P (transmission) is a value that is determined by the pump's ejection pressure, piping pressure loss, etc., but there is a limit due to the pump capacity cost, piping cost, etc., and it is generally pmz-3 to 5.
KVC,1 is adopted.

Therefore, the flow rate control range for a single nozzle α = Q6/Q *i
u is P m = 0.5, P ” = 5 KVca
Even so, only α=Vl〒0=3.2 can be obtained.

(Purpose of the invention) The present invention has been made in view of the above situation.

A wide range of refrigerant flow control ranges has been achieved by arranging multiple nozzle groups with different flow characteristics in the same cooling device and providing a dedicated refrigerant control device for each nozzle group.

(Structure of the Invention) In other words, one gist of the present invention is that
n''+ image; In a steel cooling system in which a plurality of nozzles are arranged in series at a predetermined pitch in the longitudinal direction, the capacity of the nozzles arranged in series in the nozzle header is determined by at least one adjacent nozzle header in the upper and lower directions and in the direction of movement of the material to be cooled. This steel cooling device is characterized by having a dedicated refrigerant flow rate control system for each nozzle header unit.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 8 and FIG. 9 are examples of the cooling device of the present invention,
Fig. 10 shows an example of the use of a plurality of nozzles with different flow characteristics arranged in the same cooling device, and Fig. 11 shows the refrigerant flow control range and upper and lower surfaces obtained by the cooling device of the present invention. An example of the control range of the medium flow rate ratio is shown.

The ribs in FIGS. 8 and 9 represent the material to be cooled, 1 is a roll for transporting the material to be cooled, and 6 is a presser roll disposed above the transport roll 1 in the cooling device.

2 and 2B are headers for lower spray nozzles placed directly below the transport rolls or between the rolls.

Nozzle groups 3A and 3 each have different flow characteristics.
B is connected. Similarly, 4A and 4B are upper spray nozzle headers placed directly above the presser roll or between the rolls, and each has a nozzle group 5 with different flow characteristics.
A and 5B are installed consecutively.

Here, the reason why the nozzle groups 3A, 3B and 5A, 5B are arranged in multiple rows at symmetrical positions above and below the coolant path level between the transport rolls or between the presser rolls is shown in FIG. Depending on the refrigerant flow rate selected as shown, the upper nozzle group uses 5A.

For the lower nozzle group, in addition to 3A, 5A, 3B, and 5
B and 3A, 5B and 3B, 5A and 3. A+: 313°5
A +' 5 B and 3I3, 5A+5B and 3 A +
3. Since nozzles are used in various combinations with B, in any combination, the top and bottom are symmetrical and the rolls are cooled uniformly.

Next, nozzle headers 2A, 2B and 4A.

A method of supplying refrigerant (cooling water) to 4B will be explained.

The refrigerant 19 in the refrigerant storage tank 18 in FIG.

Furthermore, the nozzle headers 2A and 2B are attached to the collective header 9.
, 4A, 4B refrigerant supply pipe 7A.

7B, 8A, and 8B are connected, and each refrigerant supply pipe has an automatic on/off valve 111A, 14B, and 15A.

15B, flow rate control valves 10A, IOB, 12A, 12B, and flow rate measuring devices 11A, IIB, 13A, ]: 313 are provided so that the refrigerant can be turned on and off independently and can control the refrigerant flow rate. Therefore, the refrigerant 19 supplied by the pump] 7 is supplied through the automatic on-off valves 14A, 14B,
15A, 15B on/off operation, nozzle group 3A,
Out of 3B, 5A, and 5B, the flow rate controlled by the flow control valves 10A, IOB, 12A, and 128 is supplied only to the nozzle groups corresponding to the upper and lower refrigerant flow rates instructed in advance. .

In addition, in FIG. 9, nozzle headers 2A and 2B are shown.

Refrigerant supply piping 7A, 7B, 8A to 4A, 4B.

8B is not divided in the direction of movement of the cooled material of the cooling device, but it is further divided into upper and lower nozzle headers 2A, 2B, 4A, and 4B in the direction of movement of the cooled material, respectively. Automatic on/off valve, flow control valve,
If a refrigerant supply pipe with a flow rate measuring device installed therein is connected, the cooling device can supply an arbitrary flow rate depending on the advancing position of the material to be cooled.

Next, a method for selecting a nozzle group to be used will be explained with reference to FIG.

Generally f, the cooling flow rate range required for this type of cooling device is the refrigerant flow rate injected per unit time to the unit area of the material to be cooled, that is, the refrigerant flow rate density (%0 min) converted to Q =
0.5 to 5.01++7n,y,min.

In addition, usable nozzle back pressure depends on bong specifications, piping pressure loss,
Although it varies depending on the nozzle model etc., as mentioned above, P-0
5 to 5.0 Kg/c, 1, first of all, the small capacity nozzle group A is a point p, Q(A
m+n) = (15n7, select a nozzle with the characteristics of 10 minutes. This nozzle group A is Q(A憇)=Q(
A-f-)・CP-/P-")" Can be controlled with reeds,
■If it is 1.0, Q of point A (A m ) −1,
It will be 58' minutes.

Next, P −# = 0 at the high-capacity nozzle group I3 point
．． If we select a nozzle with a characteristic of Q (Bl-) ~ 1.58 and 0 minutes for I and Q (B mt ) = 5. Qtt
To,? It is possible to have a variable flow rate range from 0 to 1 minute. Furthermore, when Q≧Q (13fl), by using the small capacity nozzle group A and the large capacity nozzle group Bz at the same time, it is possible to achieve the zero point Q (
A 1 B) urn = 5. Qn? /rr? , the flow rate can be changed from minute to point Q (A+B) Whale ==6.5 B+Ts 0 minute reed.

In addition, here, in order to simplify the explanation, Q(A-)-
Q(B-”), but as you can see in Figure 1, Q(A-==)
and Q(B-===), there is a difference in the nozzle back pressure P, so the cooling rate of the material to be cooled is often not the same due to the nozzle characteristics explained in FIG.

Q (A feeling)> Q (B) This part is commonly wrapped as a feeling.

In the above explanation, in order to make it easier to understand how to select a nozzle group, we have only explained the cases where the nozzle groups are small volume user and large capacity B, but in reality, these nozzle groups are The nozzle groups are installed separately into upper nozzle groups 3A and 3B and upper nozzle groups 5A and 5B, and each nozzle group independently performs on-off and flow rate control. Therefore, as shown in FIG. 11, the lower small capacity nozzle group 3A and the lower large capacity nozzle group 3B (l
! : Upper small capacity nozzle group 5A, upper large capacity nozzle group 5B
The on/off and flow rate control method for the specified flow rate will be explained.

In general, this type of cooling device, especially one used for cooling wide materials such as thick steel plates, is designed to prevent cooling distortion of the material to be cooled.
Turn on the upper flow rate ratio -QL/QU and cool.

The optimal value for the lower/upper flow rate ratio R depends on the type of cooling device.

Nozzle model, plate thickness of material to be cooled, plate width 1 surface texture.

This value is determined empirically depending on the cooling temperature range, etc., but according to the experience of the present inventors, it is sufficient to have 'BJ=i, in the range of o to 25. Therefore, here ■-10~2
Assume that 5. Also, the type of material to be cooled.

The required refrigerant flow rate density Q to obtain the cooling rate predetermined by Shibaize etc. is defined as the average flow rate density Qm-4Qu+Q7n2 of the upper flow rate density Qu and the lower flow rate density Qt.
The necessary control range of Qm is set as Qm-0.5 to 5.
0 d/77+2. If it's a minute.

From the two equations 几=QL/Qt QIn-(Qu/Qt)/2, these relationships are expressed as the average refrigerant flow rate density Qm on the horizontal axis and the refrigerant lower/upper flow rate ratio on the vertical axis.
The result will be as shown in the figure.

That is, the solid line represents the lower flow rate density Qz, of which Qt (A= ) +s is the minimum flow rate of the small capacity nozzle group 3A, QIA 憇) is the maximum flow rate.

Qt(Afl)/Qt(A=”Lee(P m/I),
, , (the details are as explained in Figure 10).

Also, %Qt (BIIIW) is the minimum flow rate of the lower large capacity nozzle group 3B, and Q7CB-) is the maximum flow rate, and the relationship is the same as above, Ql (B-) /Qt (B~")
-(Paw/P-)I/2.

Further, Qt(A)+Qt(13tm) is the maximum flow rate when both the lower small capacity nozzle group 3A and the large capacity nozzle group 3B are used. The dotted line represents the upper flow rate density Qu, and Qu (, AmJ and Qu (A ma
) are the minimum flow rate and maximum flow rate of the upper small capacity nozzle group 5A,
In addition, Qu (Bm') and Qu (Bfi) are the minimum flow rate and maximum flow rate of the upper large capacity nozzle group 5B, and Qu CA
+ Qu (B tmtw ) is the maximum flow rate when both the upper small capacity nozzle group 5A and the large capacity nozzle group 5B are used. Also, Ql (A min ) and Qt(
Afi) and Ql; (f3 min) and Qt(Br
ax) is the same as the lower part.

fxo, each nozzle group 3A, 3B explained above.

Quantification of the minimum and maximum flow values of 5A, 5B is Qm
= 0.517/7rr? , R = 1.0-2.5 in minutes
To take f, Qt (A-1 is Qll, 5 m'
/rI? , min, 1% = 1.0 critical point■
From Ql (A urn) = Q, 5 +++7
mF4 and similarly Qu (, AmJ is Qm = 0.5
d/d, min.

R = 25 critical point ■ to Qu (A, +I
+) = 0.29171'/rr? , minutes.

The shaded area in Figure 11 is Qm = 0.5 to 50.
m゛/1r?・min, represents the possible range of flow control at R = 1.0 to 2.5, and as you can see, there are some restrictions on the control range of R with Qm) 4. , has a very wide control range of average flow density Qm and lower/upper flow ratio R.

Also, in the figure, for example, the range is represented by B/A + B.

In order to control the average flow density Qm and lower/upper flow rate ratio in this range, the automatic on/off valve 15A at the upper part is closed.
By opening B i, only the upper large capacity nozzle group 5B is used, and the lower part is the automatic on/off valve 14A, 1.4I3.
Both are open, lower small capacity nozzle group 3A and large capacity nozzle group 3
Indicates that the flow rate control region should use both B and T.

As can be seen from the above explanation, for example, Qm = 3, which is point ■ in the diagram. On? /, 1 m min, R=2.
00) When cooling the material to be cooled with the refrigerant Rit (
Well, first, the refrigerant supply pipes 8A and 8B for the upper cooling nozzle group.
Of the automatic on/off valves 15A and 15B, 15A is closed and 15B is opened, making only the large capacity nozzle group 5B usable. Similarly, for the lower cooling nozzle group, the automatic on/off valve 14A is closed and 15Bi is opened, so that only the large capacity nozzle group 3B can be used. Next, the pump 17 is started, and while injecting refrigerant from the upper and lower four-action nozzle groups, the upper and lower flow measuring devices 13B and IIB and the flow control valves 12B and IOB are operated to adjust the upper refrigerant flow rate to Qu. ==2.0tl/, 2. minute,
Also, lower refrigerant flow rate QL-40m3/Tr?・Control in minutes. After Qu and QL are stabilized, if the material 20 is sent into the cooling device 3 by the transport roll 1, the predetermined Qm is achieved.
== 3.0 'T? /, 1, minute, R-2,0
(7) A rejection is carried out.

(Effects of the Invention) As explained above, the steel cooling device of the present invention enables wide range control of refrigerant flow rate.

Furthermore, since the range of nozzle back pressure can be reduced, the cooling rate can also be controlled stably.

Although the present invention has been described with reference to the case where a steel plate is cooled while being conveyed by a roller table, there is no problem with the conveying method using a chain, a conveyor, etc., and the material to be cooled is not limited to steel plates. , it can also be applied to general steel materials such as long steel. Furthermore, although water is generally used as a refrigerant, other refrigerants can also be used.

[Brief explanation of the drawing]

1, 2, 3, and 4 are explanatory diagrams showing various aspects of conventional cooling devices, and FIG. 5 shows refrigerant flow rate ranges in the conventional devices shown in FIGS. 1 to 4. FIG. 6 is a diagram showing the relationship among jet impingement pressure, nozzle back pressure, and jet angle in the cooling device. FIG. 7 is a diagram showing the measuring method of FIG. 6. 8 and 9 are explanatory diagrams and a refrigerant supply system diagram of the apparatus according to the embodiment of the present invention, and FIG. 10 is a diagram showing the relationship between refrigerant flow rate density and nozzle back pressure in the apparatus according to the embodiment of the present invention. FIG. 11 is a diagram showing the relationship between the refrigerant amount lower/upper hole and the average refrigerant flow rate density in the apparatus according to the embodiment of the present invention. Patent Applicant Representative Patent Attorney Tomoyuki Yafuki (and 1 other person) Figure 1 Figure 3 Figure 4 Figure 5, 1;7 Figure 101!1 1 → Nozuru 5^B tP)

Claims (1)

[Claims] It is installed in the conveyance line of the material to be cooled, has a plurality of nozzle headers above and below the material to be cooled, perpendicular to the traveling direction of the material to be cooled, and further has a plurality of nozzles in the longitudinal direction of the nozzle. In a steel material cooling device in which the nozzles are connected in series at a predetermined pitch, the capacity of the nozzles connected to the nozzle header is changed in units of at least one adjacent nozzle header in the upper and lower directions and in the direction of movement of the material to be cooled. A steel cooling device capable of controlling a refrigerant flow rate over a wide range, characterized in that each unit has a dedicated refrigerant flow rate control system.