JPH0465910B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for changing acid solutions and pickling when pickling steel strips, wire rods, etc. using two or more different types of acid solutions. This invention relates to an acid solution switching system for a continuous pickling line that allows easy cleaning of tanks and piping systems.

[Conventional technology]

Oxidized scale exists in the form of a thick film on the surface of steel materials such as steel strips manufactured by hot rolling. In order to process this hot-rolled steel material in subsequent steps such as cold rolling, it is necessary to remove the oxide scale on its surface.

A typical method for removing scale is pickling, in which the steel material is immersed in an acid solution such as hydrochloric acid or sulfuric acid. The type and/or concentration of the acid solution used here may be changed depending on the material of the steel material, or the type of acid solution may be changed depending on the progress of pickling.

In order to carry out various types of pickling work, one or more acid solution storage tanks are prepared for each pickling tank.
The acid solution is supplied to the pickling tank by pumping the acid solution of the type and concentration suitable for the target material from the acid solution storage tank. In addition, when pickling is performed using different acid solutions, instead of switching the acid solution in one line as described above, a dedicated line is set up according to the steel type, such as for ordinary steel or stainless steel. A pickling treatment using For example, in Japanese Patent Application Laid-open No. 59-83784,
A multipurpose continuous pickling device has been proposed that can charge any acid solution from a plurality of types of acid solution storage tanks into a pickling tank of a pickling line.

[Problem that the invention seeks to solve]

However, in conventional acid solution supply and discharge systems, the flow of acid solution from the pickling tank and from the acid solution storage tank is in opposite directions, making it impossible to perform this process using a single piping system. . Therefore, piping and acid-resistant pumps were required for supplying acid liquid and for discharging acid liquid. As a result, the equipment has become complicated, leading to a rise in equipment costs. In addition, if the acid solution storage tank is located lower than the pickling tank, there is no need for an acid-resistant pump because the drained liquid from the pickling tank to the acid solution storage tank will fall under its own weight. A dedicated pump is installed to supply liquid to the pickling tank. Even in this case, it is necessary to provide two piping systems.

In addition, in the pickling tank, the scale that was peeled off from the steel as the pickling progressed was deposited as sludge at the bottom of the tank, and the bricks that lined the pickling tank were also peeled off and turned into scraps. It may also accumulate in the tank. When such foreign matter is present, in conventional pickling equipment, acid solution switching is performed, which includes processes such as draining the pickling tank using a top drain method using a siphon, removing sludge, and cleaning the inside of the tank. . For this reason, it has been extremely difficult to completely remove the residual acid solution and sludge at the bottom of the tank and to drain the cleaning solution inside the tank.

Therefore, the present invention aims to simplify the structure of equipment for supplying and discharging acid solution to and from such a pickling tank, and to provide an acid solution switching system that can effectively clean the pickling tank and piping system. The purpose is to provide a system.

[Means for solving problems]

In order to achieve the purpose of the acid liquid switching system of the present invention, the piping connecting the pickling tank and the acid liquid storage tank is branched into two flow paths, and these branched flow paths are interconnected. A communicating channel is formed, an acid-resistant pump is provided in the communicating channel, and valves are interposed on each of the upstream and downstream sides where the communicating channel is connected to the two channels, and the valves are opened and closed. Accordingly, the acid solution from the pickling tank to the acid solution storage tank and from the acid solution storage tank to the pickling tank always flows in one direction and passes through the acid-resistant pump.

[Function] In the present invention, coils made of various materials such as ordinary steel and stainless steel are pickled by switching between two or more types of acids and supplying them to the pickling tank.

When pickling multi-steel materials by switching the acid solution, the acid solution in the pickling tank is drained to an acid solution storage tank installed offline, and the pickling is carried out from another acid solution storage tank. Supply acid solution to the tank. At this time, the switching mechanism installed in the middle of the piping connecting the pickling tank and the acid solution storage tank allows the acid solution to always pass through the acid-resistant pump in the same direction, so that Acid liquid is supplied and drained using one system of piping and an acid-resistant pump.

〔Example〕

Hereinafter, the features of the present invention will be specifically explained using examples with reference to the drawings.

FIG. 1 shows an overall view of the acid liquid switching device in the pickling line of this embodiment.

A steel material to be pickled, such as a steel strip, is immersed in a pickling tank. In the illustrated example, pickling tanks 1a, 1
It is a three-layer system of b and 1c, and the steel material is pickled in the pickling tank 1.
A, 1b, and 1c are sequentially threaded. Tanks 2a, 2b, and 2c for storing acid liquid are connected to the pickling tanks 1a, 1b, and 1c, respectively. These tanks 2a, 2b, 2c have the ability to accommodate the entire amount of acid solution in the corresponding pickling tank 1a, 1b, 1c.

In the illustrated example, the acid liquid storage tanks 2a, 2b, and 2c each have two tanks because two types of acid liquids A and B are used selectively.

Pipes 3a, 3 connecting these pickling tanks 1a, 1b, 1c and acid solution storage tanks 2a, 2b, 2c
In the middle of b, 3c, there are pickling tanks 1a, 1, respectively.
Switching mechanisms 4a, 4b, and 4c are provided for switching the types of acid solutions A and B sent to the buffers b and 1c.

FIG. 2 is a diagram showing details of this switching mechanism. When discharging the acid solution from the pickling tanks 1a, 1b, 1c to the acid solution storage tanks 2a, 2b, 2c, the valves 21, 22 are opened, the acid solution passes through the check valve 23, and the valves 24, 25 are closed. By this,
The acid solution from each pickling tank 1a, 1b, 1c flows along a path shown by a dotted line via a valve 21, an acid-proof pump 26, a check valve 23, and a valve 22, and is sent to the corresponding tank. On the other hand,
From tanks 2a, 2b, 2c to pickling tanks 1a, 1b,
When sending acid solution to 1c, valves 24 and 2
5, pass through check valve 23, and then open valve 2.
Close 1 and 22. As a result, each tank 2a,
The acid solution from 2b and 2c flows along the path shown by the dashed line via the valve 25, acid-resistant pump 26, check valve 23, and valve 24, and is sent to each pickling tank 1a, 1b, and 1c.

That is, when discharging the acid solution from the pickling tanks 1a, 1b, 1c, and when discharging the acid solution from the acid solution storage tanks 2a, 2b,
2c to the pickling tanks 1a, 1b, 1c, the valves 21, 22,
By switching 24 and 25, the flow of the acid solution in the pipe line including the acid-resistant pump 26 and the check valve 23 is always in a constant direction. Therefore, both liquid supply and liquid drainage can be performed using one acid-resistant pump 26 and piping system. This switching system allows the acid-resistant pump and piping system to be combined into one.

In addition, piping 3a, 3b, 3c connects the pickling tanks 1a, 1b, 1c to the acid solution storage tanks 2a, 2b, 2c.
Filters 14a, 14 for removing foreign matter are installed in the middle of the
b, 14c must be provided. At this time, from the pickling tanks 1a, 1b, 1c, the valves 18a, 18
b, 18c and pipes 15a, 15b, 15c to directly reach pipes 3a, 3b, 3c, and pipes 16a, 16b, 16c and filters 14a, 14b, 14c to pipes 3a, 3b, 3c. A conduit leading to the pipe is provided.
When sending acid solution from acid solution storage tanks 2a, 2b, 2c to pickling tanks 1a, 1b, 1c, switching mechanisms 4a, 4b, 4c, piping 3a, 3b, 3
c, pipe lines 15a, 15b, 15c and valve 18
Routes a, 18b, and 18c are used. On the other hand, from the pickling tanks 1a, 1b, 1c to the tanks 2a, 2b, 2
When sending acid solution to c, valves 18a, 18b,
18c, pipe lines 16a, 16b, 16c, filters 14a, 14b, 14c, valve 16-1a,
16-1b, 16-1c and piping 3a, 3b, 3
Use c.

As a result, when the acid solution is discharged from the pickling tanks 1a, 1b, 1c, foreign substances such as sludge floating in the pickling tanks 1a, 1b, 1c and brick chips peeled off from the tank inner wall are removed from the filters 14a, 14b. ,14c
The acid liquid is separated and sent to the acid liquid storage tanks 2a, 2b, and 2c via the acid-resistant pump 26. Therefore, the lining of the acid-resistant pump 26 will not be damaged by foreign objects such as brick chips, and the life of the acid-resistant pump will be extended. Furthermore, in the example, since bricks were not used in the acid solution storage tank, the liquid supply system from the tank to the pickling tank was a pipe line that did not pass through a filter. However, when using a brick-lined tank, the filters 14a, 14b, 14
It is necessary to use a conduit (not shown) via c.

In addition, when draining the liquid from the pickling tank to the tank, the liquid can also be drained from the bottom of the tank. For example, in the case of pickling tank 1a, the sludge in the pickling tank is routed from valve W-1a at the bottom of the tank, through valve 16-2a, through filter 14a, to valve 16-1a, and to pipe 3a. This route can also be used when the amount of deposition is small.

In the example shown in FIG. 1, the switching mechanisms 4a, 4b, 4c and the piping 3a,
3b and 3c are provided. However, these can also be aggregated into one system.

FIG. 3 shows an example of this aggregated system.
In FIG. 3, components corresponding to those shown in FIG. 1 are indicated by the same reference numerals, and their explanations are omitted.

In this case, the number of acid solution storage tanks 2 to be installed is determined according to the type of acid solution used (four types in the illustrated example).

〔Effect of the invention〕

As explained above, in the acid liquid switching system of the present invention, both the acid liquid supplied to the pickling tank and the acid liquid discharged from the pickling tank flow in the same direction, and the acid-resistant pump is operated. pass. Therefore, equipment costs can be reduced by consolidating the acid-resistant pump and piping system into one system for one pickling tank. Therefore, for example, when compared with a conventional system in which the supply and discharge of acid solution are performed in separate systems, equipment costs can be reduced by approximately 50% due to the reduction in pumps, piping materials, etc. In addition, it is easy to change the acid liquid, and since the liquid is drained by a pump, the acid liquid can be changed in a short time, so that productivity can be improved.

[Brief explanation of the drawing]

Fig. 1 shows the overall configuration of the acid liquid switching system according to the first embodiment of the present invention, Fig. 2 shows the switching mechanism installed in the middle of the piping connecting the pickling tank and the acid liquid storage tank, and Fig. 3 shows the second embodiment.

Claims (1)

[Claims] 1. Branch the piping connecting the pickling tank and the acid solution storage tank into two channels, form a communication channel that connects the branched channels, and install an acid-resistant pump in the communication channel. and a valve is interposed on each of the upstream and downstream sides where the communication channel is connected to the two channels, and by opening and closing these valves, the acid solution storage tank and the acid solution are removed from the pickling tank. The acid solution from the storage tank to the pickling tank is always 1
An acid liquid switching system for a continuous pickling line, characterized in that an acid liquid switching system for a continuous pickling line passes through the acid-resistant pump as a directional flow.