JPS6320194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for treating water using ozone in a circulating roll cooling water system in a direct method of cold rolling.

[Prior art]

A conventional water treatment method of this type is shown in FIG. In the figure, 1 is a strip, 2 is a work roll for rolling this strip, 3 is a header for injecting rolling oil onto the strip 1, and 4 is a header for injecting rolling oil onto the strip 1.
5 is a cooling water header for injecting cooling water to the work roll 2; 5 is a drainage tank that collects the cooling water and rolling oil used in rolling; and 6 is a drainage tank that introduces wastewater from this drainage tank, separates oil, etc., and purifies it. water purification device, 7
8 is a water supply pump that supplies the cooled water to the cooling water header 4 through the water supply pipe 9; 10 is a new water supply pipe that supplies fresh water to the water supply pipe 9; 11 is a cooling tower that cools the purified water; A rolling oil tank 12 is a rolling oil pump for injecting the rolling oil stored in this rolling oil tank from the header 3; 13 is a rolling oil pump that regenerates the oil separated by the water purification device 6 and sends it to the rolling oil tank 11; A rolling oil regeneration device 14 is an intermittent ozone generation and supply device for intermittently injecting ozone into the roll cooling water to prevent microbial slime from adhering to the inner wall of the water supply pipe 9, and 15 is an intermittent ozone generation and supply device. An oxygen supply device that supplies raw oxygen to the generation and supply device; 16 is an ejector provided in the bypass pipe 9a of the water supply pipe 9 to suck ozone from the intermittent ozone generation and supply device 14 and dissolve it in the cooling water; 17 is an ejector provided in the bypass pipe 9a of the water supply pipe 9 This is an ejector pump for driving the ejector.

Next, the operation will be explained. Rolling oil is injected onto the strip 1 from a header 3 to lubricate between the work roll 2 and the strip 1, and cooling water is injected from a cooling water header 4 to cool the work roll 2. Cooling water and rolling oil used in rolling are collected in a drainage tank 5, and after removing impurities such as oil and iron powder in a water purification device 6, the water temperature is lowered in a cooling tower 7, and the water is sent to a water supply pump 8. Water is supplied to the cooling water header 4 at. When the roll cooling water is circulated and reused in this manner, microorganisms propagate in the water supply pipe 9 and generate slime. In order to prevent slime from adhering to the inner wall of the water supply pipe 9, a portion of the circulating roll cooling water is pumped into the ejector pump 17 to desorb and dissolve the ozone adsorbed in the intermittent ozone generation and supply device 14 under reduced pressure. 16 and used as an ejector driving fluid and water for dissolving ozone, high-concentration ozone water is made here and injected into the water supply pipe 9.
Ozone water is mixed with roll cooling water in the water supply pipe 9, and is sprayed from the cooling water header 4 while cleaning the inner wall of the water supply pipe 9. During this time, ozone decreases due to autolysis, reaction with organic matter in the water, and disinfection. In this way, use ozonated water once to several times a day.
Cleaning for one to several minutes each time will prevent slime from adhering to the inner wall of the water supply pipe 9. FIG. 2 is a diagram showing the relationship between ozone half-life and ozone injection amount.

The conventional water treatment method for cold strip cooling water systems is configured as described above, and since circulating roll cooling water is used as the ozone dissolving water for injecting ozone, the ozone reduction rate is fast. , the half-life of ozone is short, so in order to keep the ozone concentration in the cooling water header at the end above a certain level required to prevent slime adhesion, it is necessary to
As shown in the figure, there was a drawback that a large amount of ozone had to be injected.

[Summary of the invention]

This invention was made for the purpose of eliminating the above-mentioned drawbacks of the conventional technology, and by using water of higher quality than circulating roll cooling water as ozone dissolving water for injecting ozone, the half-life of ozone can be reduced. To provide a water treatment method for a cooling water system for a cold strip that is highly reliable and economically efficient, by increasing the length of time, thereby preventing slime adhesion with a small amount of ozone injection.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a system diagram showing an embodiment of the present invention, and in the figure, numerals 1 to 17 indicate the same or equivalent parts as in FIG. 1. 18 and 19 are valves for switching water channels, the valve 18 is provided between the confluence of the new water supply pipe 10 of the water supply pipe 9 and the cooling tower 7, and the valve 19 is provided in the new water supply pipe 10. ing. The other configurations are the same as in FIG. 1.

Next, the operation will be explained. The operation for rolling is the same as the conventional one; at this time, the valve 18 is opened,
Valve 19 is closed to circulate the roll cooling water.
Next, when cleaning the water supply pipe 9 with ozonated water,
First, open the normally closed valve 19, then close the open valve 18,
Only fresh water is sent from the fresh water supply pipe 10 to the water supply pipe 9 by the water supply pump 8. When the water in the water supply pipe 9 has been replaced with fresh water, the ejector pump 17 is started, the ejector 16 sucks ozone, the intermittent ozone generation and supply device 14 desorbs ozone and dissolves it in the new water, and the ozone is removed from the water supply pipe 9. Wash 9. When the ozone cleaning is finished, the valves are switched again to open the valve 18 and close the valve 19 to circulate the roll cooling water.

In the above embodiments, fresh water for replenishment was used as the water for dissolving ozone, but other water can be used as long as it has a longer half-life of ozone than roll cooling water and is stable in quality.

〔Effect of the invention〕

As described above, according to the present invention, since water of higher quality than circulating roll cooling water is used as the ozone dissolving water for cleaning the roll cooling water system, it is possible to maintain the ozone concentration at the end of the water supply pipe above a certain level. Even if the required initial ozone injection amount is small, slime adhesion can be prevented, the reliability is high, the device is compact, and it is economical.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional water treatment method for a cold strip cooling water system, Fig. 2 is a diagram showing the relationship between ozone half-life and ozone injection amount, and Fig. 3 is a cold strip cooling water treatment method according to an embodiment of the present invention. FIG. 2 is a system diagram showing a water treatment method for a lip cooling water system. In each figure, the same reference numerals indicate the same or equivalent parts, 1 is a strip, 2 is a work roll, 5 is a waste water tank, 6 is a water purification device, 7 is a cooling tower, 8 is a water supply pump, 9 is a water supply pipe, 10 1 is a new water supply pipe, 11 is a rolling oil tank, 13 is a rolling oil regeneration device, 14 is an intermittent ozone generation and supply device, 15 is an oxygen supply device, 1
6 is an ejector, 17 is an ejector pump, 18,1
9 is a valve.

Claims (1)

[Scope of Claims] 1. In a water treatment method for a cold strip cooling water system in which ozone is intermittently injected into the roll cooling water system in the direct method of cold rolling to prevent microbial damage. A water treatment method for a cold strip cooling water system, characterized in that water of higher quality than circulating roll cooling water is used as ozone-dissolved water. 2. A water treatment method for a cold strip cooling water system according to claim 1, characterized in that fresh water for replenishing the roll cooling water system is used as the ozone dissolving water. 3. The cold strip cooling water system according to claim 2, characterized in that during ozone injection, circulation of roll cooling water is stopped by switching a valve, and fresh water is supplied to perform ozone injection. Processing method.