JPH0315970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acid liquid sampling device for measuring the acid concentration of a pickling liquid in continuous pickling equipment for steel strips.

Generally, on the surface of hot rolled steel plate,
Oxidized scale films such as FeO, Fe ₃ O ₄ and Fe ₂ O ₃ are formed, and before passing through the next process such as cold rolling,
It is necessary to remove surface oxide scale. Generally, surface oxidation scale on the steel strip is continuously removed by continuous pickling equipment using hydrochloric acid, sulfuric acid, or the like. At this time, the pickling performance is greatly influenced by the concentration of the pickling solution. FIG. 1 illustrates changes in pickling time depending on the concentration of hydrochloric acid, and FIG. 2 illustrates changes in pickling time depending on the concentration of iron chloride. Therefore, it is known from past knowledge that pickling performance and operability can be improved by keeping the iron chloride concentration at an appropriate value and increasing the acid concentration.

However, if the acid concentration is increased more than necessary, problems arise in that the acid consumption rate deteriorates due to acid evaporation and the yield rate deteriorates due to erosion of the base metal. Therefore, it is necessary to constantly measure and monitor the acid concentration, and to adjust and manage it in accordance with the operating conditions.

As methods for measuring acid concentration, colorimetric and specific gravity methods, conductivity and specific gravity methods, and the like have been proposed. However, since both methods are indirect measurements, they are susceptible to various factors and have large errors, making them difficult to put into practical use.Concentration measurements are now performed by manual analysis using the titration method. This is the current situation. However, since this manual analysis method is a direct measurement (titration method), the measurement accuracy is good, but
It has the following drawbacks.

That is, (a) since it is a manual analysis, there are errors due to individual differences among the measurers. (b) 1 with batch sampling
Because the measurement time per measurement is long, it is not possible to analyze many times. (d) The work is dangerous as it involves direct handling of acids.

However, recently, automatic titration devices have been developed and are being used for experiments and the like.
However, when this type of commercially available automatic titration device is used in operational equipment such as a continuous pickling line for steel strips, the following problems arise. In other words, the pickling solution contains sludge, and even if a conventionally known type of filtration device is installed on the inlet side of an automatic titration device for the purpose of removing this sludge, the sludge will quickly become clogged. However, there was a problem that the pipes in the automatic titrator would become clogged if the overcapacity was not sufficient.

Generally, the pickling liquid in the pickling line contains:
It contains about 100 to 300 g/Nm ³ of sludge, and this sludge has the following particle size distribution. Note that the brick chips and rubber chips are due to deterioration of the pickling tank components or corrosion due to acid.

Iron compounds (such as FeCl ₂ or FeSO ₄ ) with a particle size of 1μ or less
80-90% Brick waste with a particle size of about 100 μm to 1 mm 7-15% Rubber waste with a particle size of 1 mm or more 3-5% However, the overmaterial of the commonly used overboard is made of fibrous polypropylene, glass wool, etc. Because the sludge is made of woven material or porous ceramics, the particle size of the sludge differs significantly as mentioned above, and the properties (rubber has increased viscosity, while brick and iron have smooth properties) are also different. In the conventionally known over-container having the above-mentioned configuration, clogging was severe (it clogged within about 1 to 2 days), which caused problems in practical use. In particular, sludge that contains a lot of rubber waste is sticky, so if the sludge has a pore diameter of 10μ to 100μ, it will block the pores and cause severe clogging. However, there was a problem that the removal effect was hardly improved.

The present invention has been made in view of the above-mentioned problems, and has a structure that prevents clogging with sludge of a filter installed in a pipe line that supplies pickling liquid from a continuous steel strip pickling tank to an automatic titration device. By doing so, the present invention aims to provide a pickling liquid sampling device that makes it possible to automatically measure the concentration of pickling liquid in a continuous pickling line for steel strips, which has been considered difficult in the past. .

The present invention will be described below with reference to embodiments shown in the drawings. Figure 3 shows a system in which the sludge in the pickling liquid supplied to the titration device is removed at the inlet side of the titration device to a level that does not cause clogging. 1 shows a configuration according to the present invention. In the drawing, 1 is a sampling liquid supply pipe, which is connected to a pickling tank or the like (not shown). 2 is a primary filter, and 3 is a pump. 4
a, 4b are secondary filters, and 5 is a flow meter. Further, 6 is an automatic titration device. 7 is a pickling liquid return pipe after concentration measurement, and 8 is a pipe for supplying pure water to the automatic titration device 6. Further, numerals 9 to 19 indicate respective valves.

Next, regarding the secondary filters 4a and 4b, the fourth to
The explanation will be based on Figure 6.

41 is a filter body, 42 is a filter material, 43 is a liquid inlet, and 44 is a liquid outlet. Further, 45 is a drain outlet. In addition, 46 is a guide for inserting and holding the overfill material 42, and 47 is a flange for replacing the overfill material 42 and inspecting the inside.

The overfill material is inserted into the inside of the overboard body 41 and fixed by a guide 46 as shown in Fig. 4, so it can be easily replaced, and since the work can be done from the top, when replacing the overfill material, it is necessary to It is safe as there is no need to remove hydrochloric acid, etc.

The details of the overfill material 42 are as shown in Figure 6, where the overfill material is roughly divided into three equal parts, top, middle, and bottom, and the top has a diameter of 1 mm to 5 mm.
The purpose of this hole 50 is to trap rubber debris with a light specific gravity.

A hole 51 with a diameter of 100μ to 1mm is opened in the middle part.
Mainly captures brick debris with medium specific gravity. The number of holes in each hole is increased as much as possible by machining in order to improve overefficiency.

There are no holes in the lower part 42a, and the sample liquid stagnates in this part, and iron with a heavy specific gravity precipitates and accumulates there.

Note that it is not necessary to divide the filtration material into three equal parts, and it is possible to make the upper part larger or the middle part larger depending on the ratio of the particle sizes of the sludge in the sample liquid.

In this way, several types of holes with different sizes are machined in a single sheet of overfill material, and in order to take advantage of the difference in specific gravity with the sludge liquid, we create holes with a size that corresponds to the particle diameter of each specific gravity. You can open the holes from the bottom to the top of the overfill so that it corresponds to the largest to the smallest. In order to enhance the sludge removal effect due to the difference in specific gravity, it is preferable that the inflow amount of the sample liquid per unit time be as small as possible.

On the contrary, the larger the size of the filter body, the better, but it is a practical problem if the delay time of the sample liquid is too long. It is preferable that the residence time inside the filter is approximately 1 to 3 minutes relative to the inflow amount.

The sludge accumulated inside the filter can be discharged from the drain outlet 45 by flowing the backwashing liquid through the liquid outlet 44. In this case, the liquid inlet 43 is kept closed. Generally, this valve is switched automatically or manually periodically, and the pressure of the backwash liquid is 2 to 5 kg/kg.
^cm2 is used.

Next, the operation will be described based on FIG. When the pump 3 is started, a sample liquid for analysis is sucked from a pickling tank (not shown), and large particles and the like are removed by the primary filter 2. Here, pump 3
As described above, since the secondary filters 4a and 4b remove sludge using the difference in specific gravity, accurate settings are required. Therefore, metering pumps are preferred. The sample liquid sucked by the pump 3 is sent to the secondary filter 4a or 4b, and sludge is removed according to the above-mentioned principle. That is, iron compounds with heavy specific gravity precipitate because there are no pores in the lower part of the overfill material. Brick waste with medium specific gravity is captured by the holes drilled in the middle of the overfill material.
Furthermore, rubber debris with the lowest specific gravity is captured in the upper hole. In addition, in Fig. 3, there are two overpass units 4a and 4b.
is provided, but of course only one overpass may be used. However, by providing two overflow devices as shown in the figure, the valves 9a, 9b, 10a, 10
b can be used alternately by controlling opening and closing, which is convenient for maintenance of the secondary filter.

The sample liquid thus clarified passes through a flowmeter 5 and is supplied to an automatic titration device 6. The analyzed sample liquid passes through piping 7 and is discharged to the outside of the system. Further, pure water is supplied from the pipe 8 to the automatic titration device 6 .

In the above, valves 11, 12, 13, 1
5, 19 are open, valves 14, 16, 17, 18
a, 18b are closed. Also, valves 9a and 10
One pair of a, 9b, and 10b is open, and the other is closed. Note that the valve 17 may be opened to allow a certain amount of water to flow. This protects the pump.

When the preset number of measurements are completed, the pump 3 is stopped, the valve 16 is opened, and the sample liquid in the piping is discharged to the outside of the system, and the sludge that has accumulated in the secondary filter or the piping is removed. That's what I do. Furthermore, it is effective to operate the pump 3 once the sample liquid has drained, since the discharge pressure will further remove the sample liquid. After performing the above operation for a predetermined period of time, sampling is started again.

If such sampling is repeated and the filter becomes dirty, perform backwashing using the following procedure. That is, first, valve 11 is closed, and valves 12 and 1 are closed.
3, 14, and 15 to clean the inside of the automatic titration device 6, and then open the valves 12, 13, and 19.
Close the valve, open the valves 11 and 17, and perform backwashing.

By controlling the above operations with a sequencer, it is possible to automatically sample and measure the concentration of the pickling solution.

Next, an example of pickling with hydrochloric acid will be described. The internal volume of the secondary filter was 1.6, and the inflow rate of the sample liquid was 1/min. Further, although polypropylene was used as the material for the overfill, any overfill material may be used as long as it is not corroded by the sample liquid.

FIG. 7 shows a situation in which automatic analysis is performed using the apparatus according to the present invention. As a result, conventional manual analysis
Measurement was performed at a rate of 4 to 5 hours per time, but once per hour.
Since analysis can now be performed at a rate of 15 minutes, the results can be fed back to the pickling solution concentration adjustment device, making it possible to keep concentration changes within ±0.5%. Note that conventionally it was about ±2.0%.

In order to backwash the secondary filter, a dedicated backwash liquid inlet 52 may be provided as shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between hydrochloric acid concentration and descaling time, FIG. 2 is a graph showing the relationship between iron oxide concentration and descaling time, and FIG. 3 is a schematic diagram of the sampling device according to the present invention. Figure 4 is a plan view of the filter, Figure 5 is a side view of the filter, Figure 6 is a perspective view of the filter, Figure 7 is a continuous measurement of HCl and FeCl ₂ concentrations, and Figure 8 is the other FIG. 1... Sampling liquid supply piping, 2... Primary filter, 3... Pump, 4a, 4b... Secondary filter, 5... Flow meter, 6... Automatic titration device, 7...
Pickling liquid return pipe, 41... Filter unit body, 42...
Overmaterial, 43...liquid inlet, 43...liquid outlet, 45
...Drain outlet, 46...Guide, 50, 51
...Perforation, 52...Backwash liquid inlet.

Claims (1)

[Claims] 1 A filter is installed in the pipe line that supplies pickling liquid from a continuous pickling tank for steel strips, etc. to an automatic titration device, and the main body of the filter is divided into an inlet side chamber and an outlet by a substantially upright plate-shaped filter material. A pickling solution sampling for measuring acid concentration, characterized in that the filter material is divided into a side chamber, and a filter hole is provided in the upper part of the filter material, and the diameter of the filter hole in the upper part of the upper part is larger than that of the filter hole in the lower part. Device.