JPH0239322B2 - ATSUENREIKYAKUSUINOOZONNYORUMIZUSHORIHOHO - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to the treatment of roll cooling water in a cold rolling mill, and relates to the treatment of roll cooling water in a cold rolling mill. This invention relates to treatment for preventing slime formation in roll cooling water for maintaining friction at an appropriate value and cooling rolls and rolled materials below a predetermined temperature.

(Prior art) Conventionally, there are two types of roll cooling methods for cold rolling mills: recirculation method and direct method. In the former method, a large amount of emulsion liquid, which is made by adding rolling oil to cooling water, is used. It circulates and supplies the rolling rolls and the material to be rolled to simultaneously lubricate and cool them. On the other hand, in the latter direct method, as shown in FIG. At the same time, cooling water is injected onto the work roll 3 through the nozzle of the roll cooling water header 4 to cool the work roll 3. The cooling water and rolling oil after injection are collected in a drainage tank 5, and after removing impurities such as oil and iron powder by a water purification device 6, they are cooled by a cooling tower 7, and fresh water is supplied from a fresh water supply pipe 8. is supplied to the pipe 1 by the pump 9.
The cooling water is supplied to the cooling water header 4 through 0 and is used for circulation. On the other hand, the oil separated by the water purification device 6 is regenerated in the regeneration device 11 and transferred to the tank 1.
The rolling oil is temporarily stored in the rolling oil header 2, where new oil is replenished as needed, and the rolling oil is supplied to the rolling oil header 2 via the rolling oil supply pipe 14 by the pump 13 for circulation.

However, in the conventional direct roll cooling method as described above, the water supply pipe 10
Microorganisms propagate inside the pipe and form slime, and as a result, the water supply pipe 10 may be blocked, or the slime that has peeled off from the inner wall of the water supply pipe may be sprayed together with cooling water from the nozzle of the roll cooling water header, causing damage to rolls or metal strips. There was a problem of scratches occurring on the surface.

Conventionally, as a countermeasure to such problems caused by slime, the following methods have been taken to suppress the generation of slime.

(1) Keep cooling water clean and suppress the growth of microorganisms by replenishing 40 to 60% of the water supply with fresh water.

(2) Chlorine or sodium hypochlorite is added to the cooling water, and its sterilizing effect suppresses slime generation.

(Problems to be Solved by the Invention) However, method (1) has the problem of large water consumption, and method (2) has the problem that the chlorine concentration in the cooling water increases during circulation, causing the metal strip to deteriorate. There were problems such as not only having a negative effect on surface quality but also high chemical costs.

(Means for Solving the Problems) An object of the present invention is to provide a roll cooling water treatment method that solves the above problems.

The inventor of the present invention aims to reduce the ozone concentration in the cooling water at the cooling water injection section to the rolls by injecting ozone into the cooling water when cooling the rolls using the direct method.
It was confirmed that slime production could be suppressed by increasing the concentration to 0.1 ppm or more.

Ozone not only has a higher bactericidal effect than the conventionally used chlorine, but also has the advantage that it decomposes into oxygen in a relatively short time and has no effect on metal strips. Ozone has a lifespan (half-life).
This brings with it new problems.

That is, while a cold rolling mill is placed indoors, water treatment equipment such as the water purification device 6 and the cooling tower 7 are usually placed outdoors, and therefore the water supply pipe 10 is very long. This is often the case. Therefore,
When ozone is supplied upstream of the water supply pipe 10, the time required for the roll cooling water injected with ozone to reach the roll cooling water header 4 at the end from the ozone supply position, that is, the residence time becomes longer; It also depends on the flow rate of the cooling water. Generally, the flow rate of roll cooling water in a cold rolling mill is controlled according to the rolling speed, so the flow rate of cooling water flowing through the water supply pipe 10 to the header 4 fluctuates, and as a result, the residence time fluctuates greatly and As shown in Figure 2, the ozone concentration at For this reason, there is a problem in that it is difficult to efficiently maintain the ozone concentration in the roll cooling water header 4 at the end of the retention period at a predetermined value, that is, 0.1 ppm or more, with an appropriate amount of ozone injection.

The present invention provides a method for solving the above problem.According to the present invention, in order to cool the rolls of a cold rolling mill, as shown in FIG. When the cooling water supplied to the cooling water header 4 is injected from the ozone generation and supply device 15 by the ejector 16 for ozone treatment, the residence time of ozone from the ozone injection point to the roll cooling water header is stabilized. , the flow rate of the cooling water is controlled to be constant at least during the ozone residence time period so as to stabilize the ozone concentration at the end.

(Function) As described above, according to the present invention, the ozone concentration in the cooling water is stabilized by controlling the flow rate of the cooling water in the water supply piping and stabilizing the residence time of ozone. A predetermined ozone concentration value can be maintained in the end roll cooling water header.

(Embodiment) In the embodiment of the present invention shown in FIG. Therefore, it is connected to be supplied to the ozone injection pipe 17, and the ejector pump 18 is configured to pass cooling water from the water supply pipe 10 to the ejector 16 at high pressure. 19 indicates an oxygen supply device.
In order to control the flow rate, a cooling water take-out pipe 20 is connected to the water supply pipe 10 upstream from the end of the water supply pipe, preferably near the header 4, and this take-out pipe 20 is connected to the return pipe 21 of the wastewater receiving tank 5. A flow rate adjustment valve 22 is provided in the take-out pipe 20, and the take-out pipe 20
A flow meter 23 is installed in the water supply arrangement 10 upstream from the connection point of
is installed, and the opening degree of the flow rate regulating valve 22 is controlled by the flow rate signal from this flow meter 23, thereby controlling the water supply arrangement 10.
The flow rate of the cooling water is kept constant during the ozone residence time period, that is, between the ozone injection point A and the connection point B of the extraction pipe 20.

(Effects of the Invention) According to the present invention, it is possible to achieve the effect that economical and stable water treatment using ozone can be performed without being affected by the amount of water in the roll cooling water header.

[Brief explanation of drawings]

Figure 1 is a system diagram of a water treatment system that ozone-treats roll cooling water, which cools the rolls of a cold rolling mill by the direct method, according to the present invention, and Figure 2 shows the relationship between the flow rate of cooling water in the water supply pipe and the ozone concentration. A graph showing the relationship, FIG. 3, is a circulation system diagram of roll cooling water that cools the rolls of a conventional cold rolling mill by a direct method. DESCRIPTION OF SYMBOLS 1...Metal strip, 2...Rolling oil header, 3...Work roll, 4...Roll cooling water header, 5...Drainage tank, 6...Water purification device, 7...
... Cooling tower, 8 ... New water supply pipe, 9 ... Water supply pump, 10 ... Water supply pipe, 15 ... Ozone generation and supply device, 16 ... Ejector, 17 ... Ozone injection pipe, 18 ... Ejector pump, 19...Oxygen supply device, 20...Cooling water take-out pipe, 21...Return pipe, 22...Flow rate adjustment valve, 23...Flow meter.

Claims (1)

[Claims] 1. When treating water by injecting ozone into the roll cooling water that is injected from the roll cooling water header installed at the end of the water supply pipe to the rolls of a cold rolling mill at the base end of the water supply pipe, A take-out pipe for taking out the cooling water from the water supply pipe is provided at a more upstream position, a flow rate of the cooling water between the proximal end of the water supply pipe and the take-out part is detected, and based on this detected value, the flow rate of the cooling water is taken out from the take-out pipe. A method for treating rolling cooling water using ozone, characterized in that the flow rate of cooling water between the base end portion and the extraction portion during ozone injection is made constant by controlling the flow rate of cooling water.