JP6052208B2 - Steel strip continuous pickling apparatus and steel strip manufacturing method - Google Patents

Description

  The present invention relates to a continuous pickling apparatus for continuously pickling steel strips.

  In order to remove the surface scale of a steel strip such as a cold rolled steel plate or a silicon steel plate, a continuous pickling apparatus for continuously pickling the steel strip is used.

  FIG. 6 shows the basic structure of the continuous pickling apparatus. As shown in FIG. 6, the continuous pickling apparatus 10 includes a pickling tank 6 filled with a pickling solution (acid solution) 2, and the pickling tank 6 is formed of a steel strip 3 by a plurality of dams 1. It is divided in the traveling direction d1 (here, divided into four pickling tanks 6a, 6b, 6c, 6d). Then, in order to replenish the acid solution 2 consumed by pickling, the height of the dam 1 is increased in order toward the steel strip traveling direction d1, and the acid solution is opposite to the steel strip traveling direction d1, and the steel strip 3 Each dam 1 is sequentially overflowed from the outlet side of the steel plate and supplied to the pickling tank upstream of the steel strip traveling direction d1 (here, pickling tank 6d → 6c → 6b → 6a).

  In such a continuous pickling apparatus 10, a dilute solution such as sulfuric acid or hydrochloric acid is usually used as the acid solution 2, and the temperature is maintained at about 80 to 90 ° C. in order to increase the pickling efficiency. .

  In order to maintain the temperature of the acid solution 2 at a high temperature, as shown in FIG. 3, the steam is directly injected into the acid solution 2 through the steam pipe 7, or the steam is used as shown in FIGS. A side-mounted heat exchanger 8 or a bottom-mounted heat exchanger 5 is installed (for example, Patent Document 1 and Patent Document 2).

  In the bottom surface installation type heat exchanger 5 shown in FIG. 5, the upper end is higher than the upper end of the bottom surface installation type heat exchanger 5 in order to prevent contact between the steel strip 3 and the side surface installation type heat exchanger 5. A protective dam 9 lower than the level of the acid solution 2 is installed.

  However, in the method using the steam pipe 7 shown in FIG. 3, since the steam is directly put into the acid solution 2, the side-mounted heat exchanger 8 and the bottom-mounted heat exchanger 5 shown in FIGS. 4 and 5 are used. There is a drawback that the amount of waste liquid increases.

  The side-mounted heat exchanger 8 shown in FIG. 4 performs heat exchange using an acid-resistant resin tube or the like, so that there is no increase in waste liquid, but the overhang dimension from the side surface of the pickling tank 6 is a steam pipe. In this case, about 250 mm is required compared to about 80 mm, and many accidents that damage the heat exchanger 8 due to the meandering of the steel strip 3 occur, which requires a large expense for maintenance and adversely affects the operation. Yes.

  On the other hand, in the bottom surface installation type heat exchanger 5 shown in FIG. 5, a tube for introducing steam to the bottom surface installation type heat exchanger 5 located on the bottom surface of the pickling tank 6 is arranged on the side surface of the pickling tank 6. Therefore, since the overhang dimension from the side surface of the pickling tank 6 can be about 80 mm, which is the same as that of the steam pipe 7, the heat exchanger 5 is hardly damaged due to the meandering of the steel strip 3.

  As described above, the method of installing the bottom surface installation type heat exchanger 5 shown in FIG. 5 includes the method of directly injecting steam through the steam pipe 7 shown in FIG. 3 and the side installation type heat exchanger 8 shown in FIG. It is superior to the method of installing.

  However, the method of installing the bottom surface installation type heat exchanger 5 is likely to come into contact with the bottom surface installation type heat exchanger 5 by lowering the height position of the steel strip 3 when the tension of the steel strip 3 is lowered when the operation is abnormal. There is. Therefore, as described above, the upper end of the protective dam 9 that is higher than the upper end of the bottom surface installed heat exchanger 5 and lower than the liquid level of the acid solution 2 is installed to prevent the steel strip 3 from contacting. The downward flow of the acid solution 2 generated when the accompanying flow collides with the dam 1 is stagnated around the bottom-mounted heat exchanger 5 by the protective dam 9, and the scale removed by pickling is the bottom-mounted heat exchange. There is a problem that it accumulates in the vessel 5 and the performance of the bottom-mounted heat exchanger 5 deteriorates.

  On the other hand, as a countermeasure against the stay of the acid liquid flow and damage to the heat exchanger, in Patent Document 3, a baffle wall having an upper end higher than the liquid surface of the acid liquid and having an opening is provided in front of the dam. By installing a heat exchanger between the baffle wall and the dam, the baffle wall prevents contact with the heat exchanger and the steel strip while avoiding stagnation of the flow of the acid solution by the opening of the baffle wall. I have to.

  In addition, as a countermeasure against the deterioration of the performance of the heat exchanger due to the accumulated scale, in Patent Document 4, the scale accumulated in the heat exchanger is washed away by spraying compressed air or acid solution on the heat exchanger.

Japanese Utility Model Publication No. 61-102308 Japanese Utility Model Publication No. 62-106965 Japanese Utility Model Publication No. 64-37469 JP 2003-213466 A

  As mentioned above, in a continuous pickling device for steel strip, when a heat exchanger is installed on the bottom of the pickling tank, and a protective dam is installed to prevent the heat exchanger from contacting the steel strip The protective dam causes a problem that the flow of the acid solution around the heat exchanger stagnates and the scale removed by pickling accumulates.

  As a countermeasure, as in Patent Document 3, a baffle wall whose upper end is higher than the level of the acid solution and has an opening is provided in front of the dam, and a heat exchanger is installed between the baffle wall and the dam. By preventing the stagnation of the flow of the acid solution while preventing contact between the heat exchanger and the steel strip by the baffle wall, or by blowing compressed air or acid solution on the heat exchanger as in Patent Document 4 It is conceivable to wash away the scale attached to the heat exchanger.

  However, as in Patent Document 3, when a baffle wall whose upper end is higher than the liquid surface of the acid solution is provided in front of the dam, the steel strip is exposed from the acid solution in front of the dam, so the baffle wall is Compared with the case where it is not installed, there is a problem that the acid solution passage length of the steel strip is reduced and the pickling efficiency is deteriorated.

  In addition, as in Patent Document 4, when compressed air or acid solution is sprayed on the heat exchanger, problems such as deterioration of the basic unit of compressed air or occurrence of pickling unevenness due to adhesion of bubbles to the steel strip, or spraying For example, there is a problem that a large amount of labor and cost are required for maintenance and management of equipment.

  The present invention has been made in view of the above circumstances, and in a steel strip continuous pickling apparatus, when a heat exchanger is installed on the bottom surface of the pickling tank, deterioration of pickling efficiency and equipment To provide a steel strip continuous pickling apparatus that can efficiently prevent contact between the heat exchanger and the steel strip and suppress the accumulation of scale on the heat exchanger without complicating maintenance. It is intended.

  In order to solve the above problems, the present invention has the following features.

[1] A continuous pickling apparatus for continuously pickling steel strip, a pickling tank divided by a dam in the steel strip traveling direction, and a heat exchanger installed on the bottom surface of the pickling tank, A protective dam installed to sandwich the heat exchanger with the dam,
The protective dam is a protective dam with a slit structure having a slit whose upper end is higher than the upper end of the heat exchanger and lower than the level of the acid solution in the pickling tub and through which the acid solution can pass. A continuous pickling apparatus for steel strips.

  [2] A method for producing a steel strip, comprising producing a steel strip by continuously pickling the steel strip using the continuous pickling apparatus for steel strip according to [1].

  In the present invention, in the continuous pickling apparatus for steel strip, when a heat exchanger is installed on the bottom surface of the pickling tank, the upper end is higher than the upper end of the heat exchanger as a protective dam for protecting the heat exchanger. And since it is lower than the level of the acid solution in the pickling tank and a protective dam with a slit structure having a slit through which the acid solution can pass, the steel strip is exposed from the acid solution. Therefore, even if the height of the steel strip drops when the steel strip tension drops due to abnormal operation, contact between the heat exchanger and the steel strip can be prevented without deteriorating the pickling efficiency. At the same time, the downward flow of the acid solution generated when the accompanying flow of the steel strip collides with the dam passes through the slit, so the flow of the acid solution around the heat exchanger sandwiched between the protective dam and the dam is accelerated. As a result, heat is maintained without complicating equipment maintenance. Scale of the deposition of the exchanger can be suppressed.

  That is, according to the present invention, it is possible to efficiently prevent contact between the heat exchanger and the steel strip and suppress accumulation of scale on the heat exchanger without causing deterioration of pickling efficiency and complication of equipment maintenance management. .

It is a side view which shows one Embodiment of this invention. It is AA arrow sectional drawing in FIG. It is a figure which shows a prior art. It is a figure which shows a prior art. It is a figure which shows a prior art. It is a figure which shows the basic composition of the continuous pickling apparatus of a steel strip.

  An embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing a steel strip continuous pickling apparatus 10A according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA in FIG.

  First, the basic configuration of a steel strip continuous pickling apparatus 10A according to an embodiment of the present invention is the same as that of the continuous pickling apparatus 10 shown in FIG.

  That is, the continuous pickling apparatus 10 </ b> A in this embodiment includes a pickling tank 6 filled with a pickling solution (acid solution) 2, and the pickling tank 6 is advancing the steel strip 3 by a plurality of dams 1. It is divided in the direction d1. Then, in order to replenish the acid solution 2 consumed by pickling, the height of the dam 1 is increased in order toward the steel strip traveling direction d1, and the acid solution is opposite to the steel strip traveling direction d1, and the steel strip 3 Each dam 1 is sequentially overflowed from the outlet side of the steel sheet and supplied to the pickling tank upstream of the steel strip traveling direction d1.

  And FIG. 1 is the figure which extracted and showed a part of the pickling tank 6 divided | segmented into the steel strip advancing direction d1.

  As shown in FIGS. 1 and 2, the continuous pickling apparatus 10 </ b> A is provided with a bottom-installed heat exchanger 5 on the bottom surface of the pickling tank 6 near the upstream side d <b> 1 in the steel strip traveling direction of the dam 1. Furthermore, a protective dam 4 for protecting the bottom surface installation type heat exchanger 5 is installed so as to sandwich the bottom surface installation type heat exchanger 5 with the dam 1.

  The protective dam 4 has a slit 4a through which the acid solution 2 can pass while the upper end is higher than the upper end of the bottom surface installation type heat exchanger 5 and lower than the level of the acid solution 2 in the pickling tank 6. It becomes the protection dam 4 with a slit structure which has.

  Thereby, in this continuous pickling apparatus 10A, the upper end of the protective dam 4 with the slit structure is higher than the upper end of the bottom surface installation type heat exchanger 5 and lower than the liquid level of the acid solution 2 in the pickling tank 6. Therefore, since the steel strip 3 is hardly exposed from the acid solution 2, the pickling efficiency is deteriorated even when the height of the steel strip 3 is lowered when the tension of the steel strip 3 is lowered due to abnormal operation. Without incurring contact with the bottom surface heat exchanger 5 and the steel strip 3.

  Further, when an accompanying flow f1 is generated around the steel strip 3, and when the accompanying flow f1 collides with the dam 1, a downward flow f2 is generated, the downward flow f2 is converted into a protective dam 4 with a slit structure. , The flow of the acid solution 2 around the bottom-mounted heat exchanger 5 sandwiched between the dam 1 and the protective dam 4 with the slit structure is accelerated, resulting in a complicated facility maintenance management. In addition, it is possible to suppress the accumulation of scale on the bottom-mounted heat exchanger 5.

  In other words, in this embodiment, the contact between the bottom-mounted heat exchanger 5 and the steel strip 3 is prevented and the scale to the bottom-mounted heat exchanger 5 is obtained without causing deterioration of pickling efficiency and complication of equipment maintenance management. It is possible to efficiently prevent the accumulation of sediment.

  When the continuous pickling apparatus according to the prior art shown in FIG. 5 is used, the heat build-up efficiency is reduced due to the accumulation of the scale on the bottom-mounted heat exchanger 5 after about 3 months of use. Deformation and damage of the bottom-mounted heat exchanger 5 due to the occurrence occurred. For this reason, it is often necessary to replace the bottom-mounted heat exchanger 5 or the like.

  On the other hand, when the continuous pickling apparatus according to one embodiment of the present invention is used, scale build-up on the bottom-mounted heat exchanger 5 is suppressed even after 6 months of use, and heat exchange is performed. Deformation / damage of the bottom-mounted heat exchanger 5 due to the decrease in efficiency and the occurrence of uneven heat did not occur.

  Thus, by using the continuous pickling apparatus of the present invention, the contact between the heat exchanger and the steel strip can be prevented and the scale to the heat exchanger can be achieved without deteriorating the pickling efficiency and complication of equipment maintenance management. It is possible to efficiently prevent the accumulation of sediment.

DESCRIPTION OF SYMBOLS 1 Dam 2 Acid liquid 3 Steel strip 4 Protection dam with slit structure 4a Slit 5 Bottom installation type heat exchanger 6 Pickling tank 6a, 6b, 6c, 6d Pickling tank 7 Steam pipe 8 Side installation heat exchanger 9 Protection dam DESCRIPTION OF SYMBOLS 10 Continuous pickling apparatus 10A Continuous pickling apparatus d1 Steel strip traveling direction f1 The accompanying flow of the steel strip f2 The downward flow generated by the accompanying flow colliding with the dam

Claims (2)

A continuous pickling apparatus for continuously pickling a steel strip, a pickling tank divided by a dam in the direction of travel of the steel strip, a heat exchanger installed on the bottom surface of the pickling tank, and the dam And a protective dam installed so as to sandwich the heat exchanger,
The heat exchanger is installed only on the upstream side in the steel strip traveling direction in the vicinity of the dam, and the protective dam has an upper end higher than the upper end of the heat exchanger and the acid solution in the pickling tank. By being a protective dam with a slit structure having a slit through which the acid solution can pass while being lower than the liquid level , contact prevention between the heat exchanger and the steel strip and deposition of scale on the heat exchanger A continuous steel pickling device for steel strips characterized by deterrence .   A steel strip is produced by continuously pickling steel strip using the continuous pickling apparatus for steel strip according to claim 1.

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