JP2775444B2 - Pickling equipment for strip steel - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a strip pickling apparatus, and more particularly to a strip pickling apparatus in which a thin steel sheet is continuously passed from a front tank to a rear tank while being immersed in a plurality of pickling tanks. The present invention relates to the structure of a pickling tank of a continuous pickling apparatus.

(Prior art) In recent pickling apparatuses for hot-rolled steel sheets, a plurality of pickling tanks are arranged side by side in the line direction, and the strips are continuously passed through each tank without stopping in each pickling apparatus. The method of going is taken. As a tank type of such a continuous pickling apparatus, a deep immersion type, a turbulent cell type, a shallow type and the like are known. In both cases, a large amount of liquid is taken out from the outlet side of the tank along with the running of the steel strip.As a countermeasure, an acid circulation pump is installed to maintain the liquid level, or seals are placed on the inlet and outlet sides of the tank. Rolls have been developed in which a steel strip is passed between the upper end of the front and rear walls of the tank and the seal roll, and the liquid level is kept higher than the seal roll (for example, Japanese Patent Application No. 62-142801). .

(Problems to be Solved by the Invention) The conventional continuous pickling equipment of the deep immersion type requires a large amount of treatment liquid because the steel strip hangs deeply in the liquid in each tank, and requires a large amount of treatment liquid. There is a problem that the catenary fluctuates up and down in the tank due to the speed fluctuation, causing uneven pickling. In the case of the shallow type, a tank with a shallow bottom and a long length is used, so there is an advantage that the amount of liquid may be small. As a result, there is a problem that the liquid level on the tank entrance side drops and stable pickling operation cannot be performed. In particular, when the speed of the steel strip increases with the recent high-speed processing, if the liquid level 20 drops to 20 'on the entry side of the pickling tank 7 as shown in FIG. As a result, the steel strip 1 dries up, and a predetermined immersion length cannot be obtained. Even if an acid circulation pump is used as in the prior art, the amount of acid solution taken out is large, the power consumption for driving a large-capacity pump is large, and the pickling cost is high. When a seal roll is provided to maintain the liquid level high, the strip steel plate is prevented from drying up at that part, but the liquid volume is required to be large and the liquid outflow is also large, and the same large capacity There was a problem that a pump was required.

The present invention provides a strip plate pickling apparatus capable of constantly obtaining a predetermined liquid depth over the entire length of the tank with a small amount of outflow of the acid solution, thereby reducing the capacity of the acid solution circulation pump and improving the energy saving effect. Is to do.

(Means for Solving the Problems) The pickling apparatus for a strip steel sheet according to the present invention comprises a plurality of pickling tanks arranged along the running line of the strip, and a plurality of pickling tanks on the outlet upper edge of the pickling tank. A seal roll for pressing the plate against the upper edge of the tank is provided, and the acid solution is injected into the tank near the upper edge of the tank on the inlet side and in a direction opposite to the overflow of the acid solution from the upper edge of the tank on the inlet side. And a return flow path connecting the inlet side and the outlet side of each pickling tank, and moved to the tank outlet side along with the running of the strip, and In this case, the acid solution having a higher flow rate flows through the return flow channel to the tank inlet side having a lower liquid level.

(Examples) Next, the present invention will be described with reference to the drawings with respect to examples.

FIG. 1 is a side sectional view of a shallow pickling apparatus according to a first embodiment of the present invention. In the pickling apparatus of this embodiment, the pickling tank is formed by connecting two to five tanks along the traveling line direction of the strip 1, and FIG. 1 shows only one of them. The pickling tank 7 is provided with a brick lining 8 on the inner surface.
A protective skid 9 is attached to prevent the device from being damaged. As described above, the skid 10 is provided at the upper edge of the front end and the rear end of each of the plurality of pickling tanks 7, and the skid 10 is slightly above the rear end (tank outlet) side skid 10 in the illustrated embodiment. A large-diameter seal roll 5 is supported by a large gap. A pair of ringer rolls 2 and 5 are provided between the adjacent pickling tanks 7 so that the acid solution adhering to the surface of the steel strip 1 is squeezed by the ringer rolls 2 and 5. Liquid return ports 11 are provided on the inlet side and outlet side of each pickling tank 7 and outside the tank upper edge skid 10, respectively, and these liquid return ports 11 communicate with an acid liquid recovery tank 13 via a pipe 12. Have been. Further, an acid solution supply header 14 for injecting and supplying an acid solution from near the upper end of the tank upper edge skid 10 on the inlet side and the outlet side of each pickling tank 7 toward the inside of the tank is provided. From 13, the acid solution 4 is supplied into the tank via the heat exchanger 16 by the acid solution circulation pump 15. An acid solution overflow port 17 is provided at an appropriate position on the side of the tank.

In the embodiment shown in FIG. 1, a return pipe 3 is provided which connects the bottom of the pickling tank 7 near the inlet side and the outlet side outside the tank body. The return pipe 3 serves to return the acid solution 4 from the outlet side to the inlet side so that the liquid level on the tank inlet side and the liquid level on the outlet side are always equal. That is, when the strip steel sheet 1 moves in the tank while being immersed in the acid solution, the liquid flows along the flow of the strip steel sheet to the tank outlet side, and as a result, the liquid surface has a gradient. However, as described above, in the present invention, since the front and rear portions of the tank are connected by the return pipe 3 in a form separated from the passage of the steel strip 1 in the tank, the acid solution which flows to the outlet side and has a higher liquid level is returned. It flows through the flow pipe 3 to the lower inlet side of the liquid surface, whereby the gradient of the liquid surface is corrected, and a predetermined immersion depth can be obtained even if there is a speed fluctuation in the steel strip, as described in FIG. Drying does not occur at the tank entrance side. In FIG. 1, A shows the liquid level at the time of operation without the return pipe, and B shows the liquid level at the time of stop.

In the embodiment shown in FIG. 1, the return pipe 3 is arranged below the pickling tank 7, but as shown in FIGS. 2 (a) and 2 (b), both sides outside the pickling tank 7 are provided. Alternatively, the return pipe 23 may be provided so as to be connected from the vicinity of the insertion port to the vicinity of the outlet. In each of these embodiments, the return pipes 3 and 23 are arranged outside the tank 7 and are fixed to the connection port formed in the tank with bolts or the like, but FIGS. 3 (a) and 3 (b). As in the example shown in
A pair of partition plates 33 may be formed on the tank bottom wall from near the tank inlet to near the outlet to partition between the steel strip 1 in the tank 7 and the inner wall of the tank along the flow direction of the steel strip. . The upper edge of the partition plate 33 is made slightly higher than the liquid level 20, and the front and rear ends of each partition plate 33 are opened to the tank inner wall, whereby the partition plate 33 is pulled by the strip 1 and moves to the tank outlet side. The separated acid solution 4 flows from the downstream end of the partition plate 33 to the partition plate 33 and the inner wall of the tank.
It may return to the tank inlet side through the space between 7a. The hollow portions of the return pipes 3 and 23 and the space between the partition plate 33 and the inner wall of the tank serve as a return path 43 for the acid solution. In the case of FIGS. 3 (a) and 3 (b), the liquid in the return channel 43 is not attracted to the steel strip due to the viscosity accompanying the running of the steel strip 1, but is brought about by the running of the steel strip 1. The liquid flows backward from the tank outlet side to the inlet side so as to eliminate the liquid level difference between the tank inlet side and the outlet side. In the embodiment of FIGS. 2 (a) and 2 (b), the connection port on the side of the pickling tank connecting the return pipe 23 may also be used as the overflow port of the tank. In this case, the height of the overflow port may be the same on the inlet side and the outlet side, but the outlet side is formed at a position higher than the inlet side, and the return pipe 23 is provided with a gradient corresponding to this. The liquid flow becomes smoother.

The acid solution supply header 14 described with reference to the embodiment of FIG. 1 is located above the inlet side pass line for one tank as shown in FIG.
It is provided at four places below the pass line, above the exit-side pass line, and below the same pass line so as to oppose the overflowing flows. As a result, the amount of liquid that tends to flow out to the acid solution recovery tank 13 as the strip 1 travels can be reduced. In this embodiment, since the seal roll 5 is provided above the exit-side pass line, the overflow amount is relatively small. In some cases, the acid solution supply header at this position can be omitted. The relationship between the seal roll 5 and the ringer roll 6 on the downstream side is shown in FIG.
A difference in height H is provided between the lower surface and the pressing surface of the ringer roll 6, so that the strip 1 runs in contact with the lower surface of the seal roll 6, and the amount of overflow from the upper surface of the strip 1 is minimized. It is better to reduce it.

Next, in the embodiment of FIG. 1, in addition to the outer cover 21 on the entire upper surface of the tank usually provided in this kind of pickling tank 7, the inner cover extending from a position near the inlet side skid to a position immediately before the outlet side seal roll 5 is provided. A cover 22 is provided. As shown in FIG. 5, the inner cover 22 has a hanging member 25 having an elongated hole 24 protruding upward.
Is fixed, and a shaft 26 provided on the back surface of the outer cover 21 is inserted into the elongated hole 24, whereby the inner cover 22 is
It is hung up and down on 21. Pickling tank 7
A fume duct 28 communicating with a space 27 between the inner cover 22 and the outer cover 21 is formed on the side of the so as to extend along the longitudinal direction of the tank, and is generated in each of the tanks 7 during the pickling operation. The fumes from the space 27 between the inner and outer covers
And is discharged from the tank longitudinal end. By providing such an inner cover 22 in contact with the upper end of the tank, the generation amount of hydrochloric acid fume in the tank is reduced,
Due to this decrease in the amount of hydrochloric acid fume, about
Fume heat loss, which accounts for 15%, can be suppressed to around 5%.

(Effect of the Invention) As described above, according to the present invention, an acid solution return flow path is formed from the outlet side of the pickling tank to the inlet side separately from the flow path of the strip steel sheet, and the strip steel sheet travels. By flattening the accompanying liquid level difference in the return flow path, a predetermined liquid depth can be ensured over the entire length of the pickling tank, and particularly stable drying is performed without drying up at the tank inlet side. Can be implemented. By performing the combined use of an acid solution supply header and a seal roll as in the example, the height difference of the liquid level is further reduced,
At a speed of 200 m / min. Of strip steel, the outflow of acid solution can be reduced to about 1/2 of the conventional level.According to the decrease in outflow, the capacity of the acid solution circulation pump and the amount of acid solution itself can be reduced. Energy conversion is achieved. With the reduction of the fumes of hydrochloric acid by the inner cover, a continuous pickling apparatus with high efficiency and energy saving effect can be obtained as a whole.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a pickling apparatus according to a first embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are schematic top views and cross sectional views of a second embodiment of the present invention. , FIG. 3 (a), (b)
FIG. 4 is a schematic top view and a cross-sectional view of a third embodiment of the present invention. FIG. 4 is a schematic enlarged side view of a seal roll and a ringer roll at a tank outlet in the present invention. FIG. 6 is a side sectional view showing a dry state of a steel strip at the entrance of a conventional pickling tank, in which the inner cover is provided with an embodiment of the present invention. 1 ... steel strip, 2,6 ... ringer roll, 3,23 ... return pipe, 5 ... seal roll, 7 ... pickling tank, 14 ... header for acid solution supply, 21 ... outer cover , 22 ... Inner cover, 33 ... Partition plate, 43 ... Return channel.

Claims (1)

(57) [Claims] 1. A plurality of pickling tanks arranged along a running line of a strip are provided with a seal roll for pressing the strip against the upper edge of the tank at an outlet side of the pickling tank at an outlet side thereof. In the vicinity of the upper edge of the tank, and an acid solution supply header for injecting the acid solution into the tank from a direction opposite to the overflow of the acid solution from the upper edge of the inlet side tank, and further, each pickling tank A strip return line connecting the inlet side and the outlet side.