JPS6210715B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a device for suppressing biofouling in water pipes through which seawater or the like flows. A large amount of seawater is used as cooling water in power plants, chemical factories, etc., but due to microorganisms and algae in the water, slime and other substances adhere to water pipes and heat exchangers, causing blockage of pipes and heat exchangers. This causes a decrease in exchange efficiency. As a measure to prevent this type of biological damage, there is a device in the prior art that intermittently injects relatively high concentration ozone into water pipes. A small, small-capacity ozone generator is used as a device for intermittently injecting high-concentration ozone.The ozone generated by this is adsorbed and accumulated on an adsorbent, and the ozone is desorbed from the adsorbent during ozone injection. It is advantageous in terms of equipment costs and operating costs. As an example of such a device for intermittent ozone injection, its structure and operation will be explained below with reference to FIG. FIG. 1 is a system diagram showing a conventional biofouling control device. In the figure, 1 is an ozone generator, 2 is an oxygen supply source that supplies oxygen to the ozone generator 1, and 3 is the ozone generator 1. Adsorption/desorption tower 4
5 is a cooling source for cooling the adsorption/desorption tower 4, 6 is a heating source for heating the adsorption/desorption tower 4, and 7 is for injecting ozone from the adsorption/desorption tower 4. A water ejector, 8a to 8g are respective switching valves, 9 is a water pipe for driving the ejector connected to the water ejector 7, and 10 is a water pipe 9 for driving the ejector.
A cooling water pipe 11 connected to the ejector driving water pipe 11 is an ejector driving pump provided in the ejector driving water pipe 9. The adsorption/desorption tower 4 has a double cylinder structure, of which the inner cylinder 4a is filled with an ozone adsorbent, and the outer cylinder 4b is filled with a heat medium. Furthermore, silica gel is generally used as the adsorbent, and ethylene glycol or alcohol is used as the heat medium. The circulation blower 3, ozone generator 1, and adsorption/desorption tower 4 constitute one circulation system in this order, and the oxygen supply source 2 is connected to this circulation system.
is in contact. Next, the operation will be explained. This operation includes two operations: an ozone adsorption operation and an ozone desorption operation. First, the suction operation will be explained. Oxygen is supplied from the oxygen supply source 2 into the circulation system so that a constant pressure is maintained at all times. The pressure at this time is normally maintained at 1.5 kg/cm ² and the switching valves 8c and 8d are open. When oxygen is passed through the circulation system by the circulation blower 3, part of the oxygen is converted into ozone by silent discharge while passing through the discharge gap of the ozone generator 1, and becomes ozonized oxygen. This ozonized oxygen is transported to the adsorption/desorption tower 4. The adsorbent in the ozone adsorption/desorption tower 4 selectively adsorbs ozone, and the remaining oxygen is returned to the circulation blower 3 via the switching valve 8c.
Oxygen consumed as ozone is replenished from the oxygen supply source 2. At this time, the temperature of the ozone adsorbent is cooled to −30° C. or lower by the cooling source 5. This is because the amount of ozone adsorbed by the adsorbent varies greatly depending on the temperature. That is, when the temperature is lowered, the amount of ozone adsorbed increases, and conversely, when the temperature is raised, the amount of ozone adsorbed is decreased. Therefore, when desorbing ozone, the temperature of the adsorbent is increased. When the adsorbent in the ozone adsorption/desorption tower 4 adsorbs ozone to a level close to the saturated adsorption amount, a transition is made to the desorption operation. During desorption operation, ozone generator 1, circulation blower 3, and cooling source 5 are used.
stops operating, and the switching valves 8a, 8b, 8c, 8d
closes. Thereafter, the heat source 6 and water ejector 7 start operating, and the switching valves 8e, 8f, and 8g open. At this time, heat is applied from the heating source 6 to increase the temperature of the adsorbent so that the ozone adsorbed on the adsorbent is easily desorbed. Then, the ozone in the ozone adsorption/desorption tower 4 is sucked under reduced pressure by the water jet ejector 7, and is dispersed and dissolved in water in the water jet ejector 7. The ozone water thus generated is sent to the point of use, that is, the cooling water pipe 10, and is Used to suppress adhesion. At this time, the ultimate pressure within the adsorption/desorption tower 4 due to vacuum suction is approximately -70 cmHg. When the desorption period ends in this manner, the initial adsorption operation is resumed and the operation is continuously repeated. Since the conventional biofouling control device is configured as described above, the cooling water pipe 10 is
Ozone can be intermittently injected into water pipes such as water pipes, etc. However, when seawater near coastal industrial areas is used as seawater for cooling, it is often the case that the seawater is contaminated. Because the degree of ozone varies greatly from day to day or hour to hour, the amount of ozone required increases compared to when using clean seawater, and it becomes difficult to leave a certain amount of residual ozone. If the same amount of ozone is injected as when using seawater, it will not be possible to suppress biofouling. Table 1 shows examples of the water quality of seawater and clean seawater near the coastal industrial area.

[Table] Figure 2 is a diagram showing changes over time in ozone concentration in contaminated seawater and clean freshwater. In order to suppress biofouling, it is necessary to apply
It is thought that ozone at a predetermined concentration needs to be in contact for a predetermined time, but as is clear from FIG. 2, it is difficult to maintain ozone at a predetermined concentration for a long time in contaminated seawater. In order to maintain ozone at a predetermined concentration or higher in water pipes through which contaminated seawater is flowing, it is necessary to inject a large amount of ozone into the water pipes compared to the amount of ozone injected into water pipes through which clean seawater is flowing. However, it is necessary to install several ozone injection points or to install an ozone injection amount control device that controls the amount of ozone injection depending on the concentration of contaminants, which poses a major practical problem. This invention was made to eliminate the drawbacks of the conventional ones as described above, and when injecting ozone into water pipes from an intermittent ozone injection device, the water to be injected and dissolved is separated from contaminated water such as seawater. The purpose of the present invention is to provide a biofouling control device that extends the life of ozone in water by providing clean fresh water. An embodiment of the present invention will be described below with reference to FIG. FIG. 3 is a system diagram showing a biofouling suppression device according to an embodiment of the present invention, and the same parts as in FIG. In the figure, 12 is a solenoid valve, 13 is a pump that supplies clean fresh water from a fresh water supply source 14 to the cooling water pipe 10 via the solenoid valve 12, and 15 is another solenoid valve provided in the cooling water pipe 10. Next, the operation of this device will be explained. When the adsorbent in the adsorption/desorption tower 4 adsorbs ozone close to the saturated adsorption amount, it switches to desorption operation, and the switching valves 8a,
8b, 8c, and 8d are closed, switching valves 8e, 8f are opened, and the heat source 6 starts operating. After that, the ejector drive pump 11 and the electromagnetic valve 12 are opened in conjunction with the ejector drive pump 11, the electromagnetic valve 15 is closed, and the pump 13 is activated to start fresh water injection, and then the switching valve 8g is opened, Ozone injection into the cooling water pipe 10 is started. Ozone desorption operation is once a day.
Once this ozone desorption period is over, the solenoid valve 12 is closed again, the solenoid valve 15 is opened, the fresh water injection is stopped, and the ejector drive pump 11 is stopped. The process of flowing seawater into the cooling water pipe 10 again and shifting to the ozone adsorption operation is repeated. As shown in Figure 2, 10ppm in contaminated seawater.
When injecting ozone, 30 seconds after injection,
In contrast, in clean fresh water, the residual ozone concentration remains as high as 5.5ppm even after 60 seconds of 7.4ppm after the same amount of time. A high residual ozone concentration inevitably results in a high bactericidal effect on surfaces that come into contact with it, thereby increasing the biofouling inhibiting effect. The fresh water supply device is not limited to the configuration shown in FIG. 3, but may have other configurations, and the solenoid valve 12
The types and structures of 15 and pump 13 are not limited either. Furthermore, the type of ozone generator 1 and adsorption/desorption tower 4,
The structure etc. are not limited either. Further, the water pipe for injecting ozone is not limited to the cooling water pipe, but may be any other water pipe, and the same effects as in the above embodiment can be achieved.
Further, the present invention is applicable not only to seawater but also to water pipes through which contaminated water flows. As described above, according to the present invention, by replacing the water that dissolves ozone with clean fresh water from seawater etc. during intermittent ozone injection, a constant amount of water is always maintained regardless of the level of contamination of seawater and temporal fluctuations. ,
Biofouling can be suppressed by injecting a relatively small amount of ozone.
Since the amount of fresh water supplied is only once a day for about 5 to 10 minutes, less amount is required, and a more economical biofouling control device can be obtained as a whole.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a conventional biofouling control device, Fig. 2 is a diagram showing changes in ozone concentration over time in contaminated seawater and clean fresh water, and Fig. 3 is a biofouling control device according to an embodiment of the present invention. FIG. In the figure, 1 is an ozone generator, 2 is an oxygen supply source, 3 is a circulation blower, 4 is an adsorption/desorption tower, 5 is a cooling source, 6 is a heating source, 7 is a water ejector, 8a to 8g
1 is a switching valve, 9 is a water pipe for driving the ejector, 10 is a water pipe for cooling, 11 is a pump for driving the ejector, 12,1
5 is a solenoid valve, 13 is a pump, and 14 is a fresh water supply source. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. In a biofouling control device that prevents biofouling in water pipes by intermittently injecting ozone into water pipes through which contaminated water is flowing, when ozone is injected, clean water is added to the water pipes into which ozone is injected. A biofouling suppression device characterized by comprising a freshwater supply device that supplies freshwater. 2. Claim 1, characterized in that the fresh water supply device includes a pump that injects fresh water from a fresh water supply source into a water pipe via a solenoid valve, and another solenoid valve provided in the water pipe. biofouling control device.