JPH05228455A - Method for preventing fouling of organism in water pipe - Google Patents

Abstract

(57) [Summary] [Structure] In a water pipe, etc., a dye laser capable of wavelength conversion is irradiated to microorganisms such as slime origin that are floating in water and microalgae. This is an adhesion prevention method. [Effect] Laser irradiation is performed on water containing aquatic organisms that flows through water pipes such as cooling water systems in nuclear power plants, thermal power plants, and various factories, so microorganisms and microalgae floating in the water can be used in equipment and pipes. And it is possible to reliably prevent it from adhering to and propagating on the cooling water pipe, and as a result, slime (microorganism film, biofilm) formed by such microorganisms and microalgae reduces the amount of water intake, heat exchangers and pumps. It is possible to prevent the occurrence of various problems such as reduced efficiency and damage. Further, since a dye laser capable of wavelength conversion is used as the laser, by setting the wavelength of the laser to a specific value, it is possible to give a damaging effect such as killing that can be said to be specific to microorganisms, microalgae and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to equipment such as cooling water systems, pipes, and water pipes in nuclear power plants, thermal power plants, and various factories that use a large amount of fresh water or seawater (these are collectively referred to as "water pipes"). A), a method for preventing the attachment of aquatic organisms that prevents the slime (microorganism film, biofilm) mainly composed of microorganisms and microalgae floating in water from adhering to the inner surface of the water pipe and propagating. Is.

[0002]

2. Description of the Related Art In a power plant or factory that uses a large amount of fresh water or seawater, the above-mentioned microorganisms, microalgae, etc. adhere to the water pipes and other water pipes to reproduce and form slime to flow. Narrow the road area. For example, in a nuclear power plant or a thermal power plant that uses a large amount of seawater as cooling water, microorganisms, microalgae, etc. are attached to equipment, pipes and cooling water pipes, and by a slime formed and propagated,
It causes various obstacles such as reduction of water intake, deterioration of efficiency of heat exchangers and pumps, and damage. Therefore, it is necessary to prevent the adhesion and reproduction of such slime.

[0003] Conventional slime adhesion preventing methods include a chemical treating method, a physical treating method and a mechanical treating method. These are summarized below.

First, as a chemical treatment method, a chemical solution injection method using hydrogen peroxide, hypochlorous acid, etc., antifouling coating,
There are an electrolytic method and a copper ion method. However, as a problem common to these methods, toxicity of chemical substances used or produced is pointed out, and environmental pollution due to this toxicity is regarded as a problem.

Next, as the physical treatment method, there are a hot water treatment method, a fresh water treatment method, a hot air drying treatment method, an electric shock method, an ultrasonic method, an ultraviolet ray irradiation method and the like. However, when carrying out the hot water treatment method, the fresh water treatment method and the hot air discharge treatment method, the cooling water system must be temporarily stopped, but temporarily suspending the cooling water system is a major problem in power plants and the like. .. In the electric shock method, about 800 V / c is applied to the entire water pipe.
Electric field strength of about m is required, and power consumption by continuous processing is large. The ultrasonic method may damage the water tube wall.

The mechanical treatment method includes a method of removing adhered slime by an underwater robot, a method of removing adhered slime by a sponge ball or a water jet, and a method of manually working by using a tool. However, in these methods, there is a problem in that the size of the apparatus is large, complicated maintenance is required, inadequacy as a processing method in a narrow pipe, and a large amount of labor and time are required. We also have a hard time treating waste.

As described above, since there are various problems in the conventional technology, the development of new technology has been earnestly desired.

[0008] Laser irradiation is used for surgery and the like in the field of clinical medicine because of its characteristic that the light energy of the living body or living body can be focused and radiated at one point on the object. There is no usage example.

An object of the present invention is to provide a method for preventing the attachment of aquatic organisms, which can overcome all the above problems of the prior art.

[0010]

Means for Solving the Problems The present invention has been devised in order to achieve the above-mentioned object, and in water pipes and the like, the origin of slime and its main constituents include microorganisms in a suspended state in water, microalgae, etc. The present invention has been completed with the finding that it is possible to effectively prevent the attachment and growth of the above-mentioned microorganisms, microalgae and the like by using a specific laser upon irradiating the laser.

That is, the method for preventing adhesion of aquatic organisms according to the present invention is characterized in that, in a water pipe or the like, a wavelength-convertible dye laser is irradiated to microorganisms such as slime origin that are floating in water and microalgae. It is a thing.

[0012] More specifically, the present invention relates to a single or a combination of equipment such as a cooling system, pipes and water pipes in a nuclear power plant, a thermal power plant or various factories that use a large amount of fresh water or seawater. Irradiating a laser beam parallel to the water flow direction or perpendicular to the water flow direction, in killing microorganisms in the floating state of water, which is the main constituent component of slime and its main component, or weakening its vitality, In this method, a wavelength-convertible dye laser is used as the laser.

A laser that can be used is a YAG laser,
It is a dye laser that uses a nitrogen gas laser as a light source (excitation source). Dye lasers are used in single wavelength, single use, or multiple wavelength, combined use.

The main factors that cause laser irradiation to kill aquatic organisms include the wavelength of laser and the light energy per unit area of irradiation. A usable laser wavelength is about 350 to 1000 nm.

[0015]

[Function] The mechanism of laser beam killing of aquatic organisms and reduction of their vitality will be described. Parallel to the water flow direction or perpendicular to the water flow direction (for example, a screen shape)
When irradiated with a laser, the laser directly hits aquatic organisms such as microbes and microalgae that float or live in water. As a result, the laser energy is absorbed by the living body, the living body is coagulated and carbonized, and the necrosis or damage of the living body occurs, which causes the death of the aquatic organism and the deterioration of the vitality, and the adhesion to the inner surface of the water pipe. Noh,
Proliferative capacity is destroyed.

Further, in the present invention, since a wavelength-convertible dye laser is used as the laser, by setting the wavelength of the laser in accordance with the type of the target organism, a damaging effect such as killing, which can be said to be specific to the organism, is obtained. Can be given.

As described above, the mechanism of action capable of giving a specific damaging effect to the target organism depending on the type of the target organism is not clear, but it is between the body color of the target organism and the wavelength of the laser. It is considered that there is a specific relationship between laser absorption and transmission.

[0018]

Embodiments of the present invention will be described.

Example 1 The structure of the experimental apparatus used in this example will be described with reference to the drawings.

In FIG. 1, seawater is the coastal seawater intake (6).
Is pumped up by the pumping pump (10) and stored in the seawater head tank (11). The seawater in the seawater head tank (11) is supplied to the laser irradiation device (1
It is sent to the seawater tank (1) in (6), then injected into one end of the irradiation water pipe (3) via the injection pipe (2), flows through the irradiation water pipe (3) to the other end, and meanders from the other end. It is discharged through the shaped discharge pipe (4). As shown in FIG. 2, monitor pipes (12) for quantitatively observing the amount of slime adhering to the wall of the discharge pipe (4) are incorporated in the three straight pipe portions, respectively. A part of seawater is discharged from the seawater head tank (11) through the laser non-irradiation section pipe (14) and the meandering discharge pipe (15). A monitor pipe is also incorporated in each of the three straight pipes of the discharge pipe (15).

In the laser irradiation device (16), as shown in FIG. 2, the injection amount of seawater into the irradiation water pipe (3) was kept constant during the experiment, and microorganisms and microalgae floating in the water Seawater containing aquatic organisms flows in the same direction in the same direction at a constant flow rate, and accordingly, aquatic organisms also flow in the water flow direction. A laser beam entrance window (5) is provided on one end wall of the irradiation water pipe (3). Irradiation water pipe (3) entrance window (5)
A nitrogen gas laser oscillator (7) for a laser light source and a dye laser oscillator (8) for wavelength conversion in front of the nitrogen gas laser oscillator (7) are installed on the extended side of the axis.

In the experimental apparatus having the above-mentioned structure, the laser beam (9) from the dye laser oscillator (8) enters the irradiation water pipe (3) through the laser beam entrance window (5), and the aquatic organism-containing seawater in the pipe is introduced. It is irradiated parallel to the water flow direction.
The aquatic organisms in the seawater that have been laser-irradiated inside the irradiation water pipe (3) are discharged from the discharge pipe (4) together with the seawater.

Seawater was passed through the irradiation water pipe (3) for 24 hours / day for 36 days, and the laser irradiation time was 8 hours / day for 36 days.

In a dye laser oscillator (8) using a nitrogen gas laser oscillator (7) as a laser source, an experiment was conducted with the laser wavelength set to 360 nm.
The amount of slime adhered to the three monitor tubes (12) in (4) was measured.

Examples 2 to 3 The same operation as in Example 1 was carried out except that the laser wavelengths were set to 480 and 590 nm, respectively, and the amount of slime deposited was measured.

Comparative Example 1 Targeting seawater flowing through the laser non-irradiated area pipe (14),
The same operation as in Example 1 was performed except that laser irradiation was not performed, and the amount of slime adhered was measured.

Table 1 shows the observation results of the examples and comparative examples.

[0028]

[Table 1] As can be seen from Table 1, the amount of slime adhered in the example is smaller than that in the comparative example. Further, among the examples, the short wavelength side is effective.

[0029]

According to the method for preventing aquatic organisms from adhering to the present invention, aquatic organism-containing water flowing through a water pipe such as a cooling water system in a nuclear power plant, a thermal power plant or various plants is irradiated with a laser. It is possible to reliably prevent microorganisms, microalgae, etc. in a floating state from adhering to and propagating on equipment, pipes and cooling water pipes, and as a result, slime formed by such microbes, microalgae (microorganism film, It is possible to prevent the biofilm from causing a variety of obstacles such as reduction of water intake, reduction of efficiency of heat exchangers and pumps, and damage.

Further, in the present invention, since a wavelength-convertible dye laser is used as the laser, by setting the wavelength of the laser to a specific value, a damaging effect such as killing, which can be said to be specific to microorganisms and microalgae, is given. be able to. Furthermore, the following effects are exhibited by the present invention.

Since the mechanism of action for preventing adhesion and growth of slime is not by chemical treatment but by physical treatment, that is, by laser irradiation, chemical substances do not affect the environment.

By continuing the laser irradiation, the slime adhesion preventing effect can be stably generated, and the effect does not decrease with time.

The apparatus used for the slime adhesion prevention method is compact in its entirety and requires a small installation space.
Also, no complicated maintenance of the device is required.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an experimental apparatus used in Examples.

FIG. 2 is a schematic view showing a laser irradiation device.

[Explanation of symbols]

 (1)… Seawater tank (2)… Injection pipe (3)… Irradiation water pipe (4)… Exhaust pipe (5)… Injection window (7)… Nitrogen gas laser oscillator (8)… Dye laser oscillator (9)… Laser Beam (12)… Monitor tube (16)… Laser irradiation device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigenori Onizuka 5-3-28 Nishikujo, Konohana-ku, Osaka City Hitachi Shipbuilding Co., Ltd. (72) Kingo Hayashi 5-28-3, Nishijojo, Konohana-ku, Osaka Within Hitachi Shipbuilding Co., Ltd.

Claims (1)

[Claims] 1. A method for preventing adherence of organisms in a water pipe or the like, which comprises irradiating a dye laser capable of wavelength conversion to microorganisms such as microalgae floating in water, which is the origin of slime, in the water pipe.