JPS59197577A - Apparatus for preparing pickling liquid - Google Patents

Abstract

PURPOSE:To make it possible to automatically prepare a pickling liquid with a predetermined concn. always with high accuracy, by controlling a feed apparatus by an operation apparatus for inputting signals from a densitometer for measuring the concn. of a charged acid, the level meter of a premixing tank and a prepared acid concn. setting device. CONSTITUTION:In a pickling liquid preparing apparatus, the concn. of a charged acid measured by a densitometer 10 is inputted to an operation apparatus 13 and a water charging amount and a charged acid charging amount are calculated from the predetermined acid concn. inputted from a concn. measuring instrument 12 and the above mentioned charged acid concn. by the apparatus 13. In the next step, a water charging control valve 8 is opened by the output signal of the apparatus 13 and water begins to be charged into a premixing tank 1. At this time, the signal of a level meter 11 is hourly inputted to the apparatus 13 and, when water reaches an objective level, the valve 8 is closed. Subsequently, a charged acid charging control valve 9 is opened by the signal of the apparatus 13 and the charged acid is charged into the tank 1 in a controlled amount. The acid adjusted to a predetermined concn. by this mechanism is sent to the premixing tank 2 through a feed-out control valve 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pickling liquid preparation device for a steel strip pickling line.

In the pickling line for copper strips, the acid concentration of the pickling solution used is a very important control item along with the temperature.

Generally, a pickling solution (hereinafter referred to as acid) is prepared by mixing water and fresh acid or recovered acid (hereinafter referred to as input acid) in a premixing tank. The prepared acid is temporarily stored in a mixing tank and then supplied to the pickling tank as make-up acid.

Conventionally, in order to make 8M of acid at a pre-mixing tank in a pre-mixing tank, the amount of water to be added to the pre-mixing tank and the amount of acid to be added are calculated from the target acid concentration, and these are calculated in the pre-mixing tank. After converting to the level, set the water level setting device and input acid level setting device to each calculated level,
Water and acid were added to each calculated level to prepare acid at a predetermined concentration.

However, the above calculations are performed by hand each time depending on the concentration of the acid to be prepared.

In addition, the concentration of the input acid, such as fresh acid or recovered acid, is usually 2
There were problems such as the accuracy of the acid concentration prepared was poor due to the bastiness of about 8 w/v %, and the surface quality of the product after pickling was adversely affected.

The present invention was developed in view of the above-mentioned conventional problems in order to control the surface quality of pickled products to a predetermined excellent surface quality. The object of the present invention is to provide a device that can automatically prepare acids with high precision at all times.

Therefore, according to the present invention, there is provided a pre-mixing tank capable of mixing water and input acid, a charging device for respectively charging water and input acid into the pre-mixing tank, and a unit capable of measuring the concentration of input acid. A concentration meter provided in the charging device, a level meter provided in the premixing tank to detect the liquid level, a concentration setting device for setting a predetermined prepared acid concentration, and the concentration meter and the level. and an arithmetic and control device connected to receive input signals from a meter and a concentration setting device, and connected to calculate amounts of water and acid to be added and control the dosing device.

A predetermined i1! is obtained by adding acid and water with a concentration of “M (”/y %)”. ] For example, 1 m of acid with an acid production concentration of C8 (ヅ■%)
3, the required amounts of water and input acid (1)H2o and (2)A are given by the following formulas.

■HO=l-C8/CM... (1)■
A-1-■H2o... (2) Therefore, once the predetermined concentration C8 is determined, by measuring the concentration of the added acid in advance, the water and the added acid can be calculated from equations (1) and (2). The amount of is required. Therefore, the levels of water and input acid in the premixing tank are calculated from this amount, and acid with a predetermined concentration can be prepared by inputting equivalent amounts of water and input acid.

In the following, the invention will be explained in more detail with reference to the drawings.

FIG. 1 shows a preferred embodiment of the pickling liquid preparation apparatus according to the present invention. In the figure, 1 is a premixing tank that can mix water and input acid, 2 is a mixing tank that receives and stores prepared acid from the premixing tank 1 via a delivery pipe 3 and a delivery control valve 4, and a supply pipe. 5 and is connected to supply acid to the pickling tank by a control valve (not shown).

A water input pipe 6 and an input acid film input pipe 7 are provided as input devices for respectively inputting water and input acid into the premixing tank 1, and input control valves 8 and 9 are provided on these input pipes 6゜7, respectively. It is configured to control the introduction of water and input acid into the premixing tank 1 by electrically controlling the opening and closing of the valves 8 and 9, respectively.

An acid concentration needle 1" O is attached to the input acid film inlet pipe 7 on the inlet side of the input acid input control valve 90, and
A level meter 11 is attached to detect the liquid level in the tank.

12 is a concentration setting device, 13 is a calculation device, and this calculation device 1
8, the predetermined acid concentration C8 set in the concentration setting device 12 and the concentration CM of input acid measured by the concentration meter 10 are input, and the input predetermined acid concentration C and input acid concentration CM are inputted. Based on equations (1) and (2), the amount of water input (
2° and the input amount V of input acid, and output control signals to the water input control valve 8 and the input acid input control valve 9, respectively.

When the illustrated apparatus configured as described above is operated, first, the concentration CM of the input acid is measured by the concentration meter 10, and this result is input to the calculation device 18. As a result, the amount of water input is determined based on formulas (1) and (2) from the predetermined acid concentration C8 inputted by the concentration measuring device 12 and the above-mentioned input acid concentration CM. . The arithmetic unit 18 calculates the input amount of acid film and the input amount of acid film.

Next, the output signal from the arithmetic unit 18 opens the water injection control valve 8, and water starts to be introduced into the premixing tank 1. At this time, the signal from the level meter 11 is inputted to the arithmetic unit 18' from time to time, and the valve 8 is closed when the target level is reached. Next, based on a command signal from the arithmetic unit 13, the valve 9 for acid injection control is opened, and the acid flows into the premixing tank 1. Thereafter, the amount of acid to be added is controlled in the same manner as in the case of water. After 1m8 of acid with a predetermined concentration has been prepared as described above, the delivery control valve 4 is opened by a command signal from the arithmetic unit 18, and the acid prepared in the premixing tank 1 is transferred to the mixing tank 2.
After being sent out through the delivery pipe 8 and temporarily stored in the mixing tank 2, it is supplied to the pickling tank.

The problem here is that the ble mixing tank 1
As more acid is added to the water, that is, as the acid concentration increases, the specific gravity also increases. Therefore, when using a differential pressure type level meter 11, it is necessary to perform correction based on this specific gravity. For this, for example, in the case of hydrochloric acid,
The relationship between hydrochloric acid concentration and specific gravity as shown in FIG. 2 may be stored in the calculation device 13 in advance.

Figure 3 shows the acid preparation accuracy according to the present invention in comparison with the acid preparation accuracy according to the conventional method.
7.% accuracy, according to the present invention, it is ±1”
The accuracy can be improved to /y%, which can greatly contribute to improving the surface quality after pickling, and furthermore, it is possible to prepare acid at a predetermined concentration with a simple operation of setting the concentration.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the apparatus according to the present invention, FIG. 2 is a graph showing the relationship between acid concentration and specific gravity, and FIG. 8 is a graph showing the acid preparation accuracy according to the present invention and the acid preparation accuracy according to the conventional method. This is a graph showing comparison. 1... Pre-mixing tank 2... Mixing tank 8... Delivery pipe 4... Delivery control valve 5... Supply pipe 6... Water input pipe
7... Acid injection pipe 8... Water injection control valve
9... Acid input control valve 10... Concentration meter
11... Level meter 12... Concentration setting device 1
3... Arithmetic device. Figure 2 Hydrochloric acid concentration C%% di

Claims (1)

[Claims] L: a premixing tank that can mix water and input acid, a charging device that inputs water and input acid into this premixing tank, a concentration meter that measures the concentration of input acid, and a liquid level in the premixing tank. a level meter that detects the level; a concentration setter that sets the desired concentration of prepared acid; and a concentration setter that controls the amount of acid and water fed by the feeding device based on signals from the concentration meter, level meter, and concentration setter. A pickling liquid preparation device characterized by comprising a controlling arithmetic device.