JPH069022Y2 - Sludge remover in pickling tank for hot rolled steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial application field> The present invention is a pickling tank for pickling and removing oxide scale on the surface of a hot rolled steel strip with hydrochloric acid, sulfuric acid, hydrofluoric acid or a mixed acid of these acids. The present invention relates to a device for removing sludge accumulated inside.

<Prior Art> Conventionally, in the pickling apparatus, the acid solution is circulated between the pickling tank and the external tank to adjust the temperature and concentration of the pickling solution. The return pipe is generally taken out from the liquid level of the pickling tank, and a so-called overflow method is generally used to keep the liquid level constant. Further, as a method for taking out the sludge accumulated in the pickling tank from the outside of the tank and separating it, for example, an acid solution or air is jetted from a pipe arranged in the pickling tank, the sludge is stirred in the solution, and returned. A method is adopted in which the acid solution is taken out of the tank together with the acid solution through a pipe, and the acid solution is filtered outside the tank to separate the sludge.

In addition, in order to take out more sludge with the returned acid solution out of the tank, a method is adopted in which the return pipe is taken out below the level of the pickling tank, and the level inside the tank is controlled by the so-called siphon method. .

FIG. 2 shows an example of a conventional pickling device of this siphon system, 1 is a pickling tank, 3 is an acid solution, 4 is an acid solution return port, 5 is a return pipe, 6 is a valve, Reference numeral 7 is a sludge, 8 is an acid liquid supply port, 10 is a pump, 11 is a filter, 12 is a siphon pipe, and 13 and 14 are tanks.

<Problems to be solved by the invention> However, in the conventional device, when the return pipe is taken out from the liquid level of the pickling tank, the specific gravity of the sludge is heavier than the specific gravity of the acid solution, so a large amount of sludge is returned. At the same time, it is difficult to discharge from the pickling tank, and when this problem is solved by the siphon method as shown in FIG. 2, the piping becomes complicated and sludge may cause clogging of the piping.

Further, in order to separate the sludge from the acid solution taken out of the tank, it is necessary to install a filter and a pump for sending the acid solution to the filter in the return pipe, which requires a large amount of equipment cost. In addition, there is a problem that the production cost increases with the operation. In addition, when the filter is washed, the line operation may be hindered, and there is a problem that the equipment cost is further increased when the spare filter is provided.

An object of the present invention is to provide a sludge removing device for pickling and feeding hot-rolled steel strips, which solves the problems of the conventional device.

<Means for Solving the Problem> The present invention installs the return pipe port for the acid solution at a position lower than the liquid level of the pickling tank, and lowers the pickling tank in the middle of the return pipe from the return pipe port. A sludge separation tank, which is a sealed container, is installed at the level, and the return pipe from the sludge separation tank is arranged so as to be raised to the same level as the liquid level of the pickling tank, and the circulation tank is lowered from the same level as the liquid level of the pickling tank. The sludge removing device in the pickling tank of the hot-rolled steel strip, characterized in that the acid solution is circulated between the pickling tank and the circulation tank.

<Operation> In FIG. 1, as the acid solution is supplied from the acid solution supply port 8, a considerable amount of the acid solution is discharged together with the sludge 7 from the acid solution return port 4 a. The discharged acid solution reaches the sludge separation tank 2 which is a hermetically sealed container through the valve 6a. In the sludge separation tank 2, sludge 7 is precipitated due to the difference in specific gravity between the sludge and the acid solution, and the acid solution 3 and the sludge are separated. 7 separates. The acid solution from which the sludge 7 has been removed reaches the liquid level of the pickling tank 1 through the valve 6b, whereby the level of the pickling tank 1 can be kept constant.

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

FIG. 1 is an overall configuration diagram showing an embodiment of the streak removing device of the present invention.

In FIG. 1, reference numeral 1 denotes a pickling tank. The pickling tank 1 is supplied with an acid solution from a circulation tank 9 by a pump 10 through a heat exchanger (not shown) or the like through an acid solution supply port 8. Is
Along with this, a considerable amount of the acid liquid is discharged together with the sludge 7 from the lower acid liquid return port 4a. The discharged acid solution reaches the sludge separation tank 2 which is a sealed container through the valve 6a of the return pipe 5a, and the sludge 7 is precipitated in the sludge separation tank 2 due to the difference in specific gravity between the sludge and the acid solution. 3 and sludge 7 are separated. The acid solution 3 from which the sludge 7 has been removed reaches the liquid level of the pickling tank 1 through the valve 6b of the return pipe 5b, whereby the level of the pickling tank 1 can be kept constant. Then, the acid solution 3 returns to the circulation tank 9 through the return pipe 5c. The valves 6c and 6d are closed during operation.

This makes it possible to discharge a large amount of sludge from the pickling tank 1, and by using the sludge separation tank 2 without using a filter or a pump in front of the filter,
The sludge can be separated, and the level control of the pickling tank 1 can be easily achieved.

When the sludge separation tank 2 is filled with the sludge 7, the valves 6a and 6b are closed and the valve 6c is opened to discharge the sludge 7 from the sludge separation tank 2.
It can be performed without stopping the line operation.
In addition, it is possible to take out the sludge from the sludge separation tank 2 with sufficient time by having a spare of the sludge separation tank and using them alternately.

Next, a specific embodiment of the present invention will be described.

In the pickling tank in which the oxide scale generated on the stainless steel surface after hot rolling was pickled with sulfuric acid, the sludge was removed using the sludge separation device according to the present invention. It is very small, and in the past, the clogging of the pipes once a month occurred, but the device according to the present invention can eliminate the clogging.

Further, by providing compressed air or an acid liquid pipe in the pickling tank and agitating the sludge accumulated at the bottom of the pickling tank by injecting the compressed air or the acid liquid, it is possible to further increase the discharge amount of sludge. there were.

The sludge removed in the sludge separation tank could be treated while the line was operating.

<Effect of the Invention> As described above, the apparatus of the present invention can discharge a large amount of sludge accumulated in the lower part of the pickling tank together with the acid solution, and utilize the difference in specific gravity between the sludge and the acid solution. Since the separation is performed by separating the sludge, the operating cost required for removing the sludge can be reduced without using a filter or the like, and the separated sludge can be treated during the line operation. Also, the liquid level of the pickling tank can be controlled.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a sludge removing device of the present invention, and FIG. 2 is an explanatory diagram of a conventional sludge removing device. DESCRIPTION OF SYMBOLS 1 ... Pickling tank, 2 ... Sludge separation tank 3 ... Acid solution, 4a ... Lower acid solution return port 4b ... Upper acid solution return port 5a, 5b, 5c ... Return piping 6a, 6b, 6c, 6d ... Valve 7 ... Sludge , 8 ... Acid solution supply port 9 ... Circulation tank, 10 ... Pump 11 ... Filter, 11 ... Siphon piping.

Front page continuation (72) Creator Teruo Oda 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works

Claims (1)

[Scope of utility model registration request] 1. A return pipe for pickling liquid is installed at a position lower than the liquid level of the pickling tank, and a sludge separation, which is a hermetically sealed container, is placed at a level lower than that of the pickling tank in the middle of the return pipe from the return pipe port. A tank is provided, and the return pipe from the sludge separation tank is arranged so as to be raised to the same level as the liquid level of the pickling tank, and is lowered from the same level as the liquid level of the pickling tank to be connected to the circulation tank. A sludge removing device in a pickling tank for hot-rolled steel strip, wherein an acid solution is circulated between the circulation tanks.