JPH03195895A - Method for preventing fouling of marine organisms and apparatus for washing ball - Google Patents

Abstract

PURPOSE:To prevent the fouling of marine organisms by periodically injecting fresh water set to specific temp. or higher in a seawater system and preventing the fouling of marine organisms in the larval stage. CONSTITUTION:Raw water is supplied to a water heater 12 from a raw water replenishing system through a raw water supply valve 22 during the stop period of ball circulation (during the OFF-period of a circulation pump 6) and heated to predetermined temp. by a heater 23. The killing temp. of marine organisms in the larval stage is 30 deg.C but the predetermined temp. is set to (30 deg.C+alpha) with due regard to the radiation from hot water injection piping. The hot water heated to the predetermined temp. is injected in a ball circulating system at the necessary time of injection by operating a hot water pump 13 but, by closing the valve 8 of the ball circulation system at this time, hot water is guided to two systems, that is, in one system, hot water is guided to a matrix pipe inlet system 2 through a ball circulating pump 6 and a ball recovery device 7 and, in the other one system, it is guided to a matrix outlet system 4 through a ball collector 5 and the hot water is injected in the whole of the circulation system. In the larval stage of marine organisms, the effective fouling preventing effect of marine organisms can be obtained without generating environment pollution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and a ball cleaning device for preventing the attachment and growth of marine organisms at the larval stage in a seawater system of a plant using seawater.

[Prior Art] Condensers installed in plants such as thermal and nuclear power plants require large amounts of cooling water, and seawater is mainly used. However, when using seawater in this way, obstacles caused by various marine organisms that live in seawater, especially shellfish such as mussels and Fujitbo, cannot be ignored.

For example, as these marine organisms attach to waterways and grow, their flow resistance increases. In particular, if it adheres to the inner surface of the tubes of a heat exchanger such as a condenser, it will block the tubes, impair heat exchange performance, and reduce the thermal efficiency of power generation equipment. In addition, localized vortices caused by adhesion can cause impact corrosion, and after the adhering organisms have died, corrosion may occur due to decomposition products of the meat.

In recent years, for mechanical cleaning of condenser tubes, a ball cleaning device has been adopted that inserts sponge balls into the condenser inlet, collects them at the condenser outlet, and circulates them back to the condenser. There are an increasing number of power generation facilities.

FIG. 4 shows a general conventional sponge ball cleaning system, in which a main pump 1 and a main pump pump 2. A ball collector 5. A ball circulation system consisting of a ball circulation pump 6, a ball recovery device 7, and ascending numbers 8 to 11 is installed. Pump 1 operates as a heat exchange system, and during this operation, cooling water flows through pump 1 → system 2 → heat exchanger 3 → collector 5 → system 4
flowing through the threads of Cooling water also flows during cleaning with the ball and when hot and cold water is injected.

During cleaning, the ball circulation pump 6 sends the sponge balls 2A in the ball collector 7 to the main tube inlet system 2, and the diameter of the sponge balls 2A is set larger than the diameter of the thin tube 2B. Move while rubbing inside 2B. The inner wall of the thin tube is rubbed by the sponge ball 2A, thereby cleaning the inner wall. In this way, the thin tubes 2B in the heat exchanger 3 are cleaned, and the cleaned balls are guided into the ball circulation system again by the ball collector 5 installed in the main tube outlet system 4, and the ball circulation pump 6 is passed through the ball circulation system. The ball passes through and returns to the ball collector 7.

However, the growth of marine organisms in the ball circulation system of this ball cleaning device becomes an obstruction in the piping, causing stagnation and clogging of the cleaning balls, and hindering the circulation of the balls. The function of tubular washing may also be impaired. Moreover, even when marine organisms initially attach, it is impossible to remove the marine organisms because the sponge balls themselves are soft.

Conventional methods for preventing the growth of marine organisms include the following.

(1) Method using chlorine injection: This is a method in which chlorine is injected into the cooling water main pipe.As is well known, chlorine has a high sterilizing power against marine organisms, and it is used to electrolyze seawater and convert chlorine ions in the seawater into hypozinc acid. A method for preventing the adhesion of marine organisms by causing them to develop (Japanese Patent Application Laid-Open No. 62-2884'18).

(2) Method using antifouling paint: A method of applying antifouling paint to areas where marine organisms are attached.

(3) Method using freshwater injection: A method in which freshwater is injected into the target strain by utilizing the effect of suppressing the survival of marine organisms in freshwater (Japanese Patent Application Laid-Open No. 58-30480, JP-A No. 63-243698, JP-A No. 63-243698, (Sho 57-101299).

(4) Method of hot water injection: A method of supplying warm water to the target system by utilizing the effect of suppressing the survival of marine organisms in warm water (Japanese Patent Application Laid-Open No. 58-30480).

[Problem to be solved by the invention]

The above-mentioned conventional technology is characterized by the following points. That is, in the method using chlorine injection, the flow rate of cooling water used in the power plant is extremely large.

If an effective amount of chlorine is injected into this system, the wastewater seawater may have a negative impact on the marine ecosystem, so its use is decreasing from the standpoint of environmental conservation.

Furthermore, even when using antifouling paints, most of the antifouling paints with high antifouling effects and long lifespans contain heavy metals.
Improvements are required from an environmental perspective.

In addition, the method of injecting fresh water has the advantage of being effective in controlling marine organisms by exposing them to fresh water for a long period of time, and has the advantage of being ineffective. 1 time/1-3 like a device
It is hard to say that the applicability of this method during stoppage is sufficient for something that operates at a frequency of about a day or so.

Furthermore, the method of hot water injection is aimed at removing members of marine organisms, and does not have the perspective of removing young shellfish, nor does it have the perspective of removing marine organisms that adhere to the ball cleaning device. .

Therefore, if special measures such as those mentioned above are not taken, the ball circulation system may be regularly cleaned and removed using jet water or removal tools, resulting in significant losses in terms of personnel costs and plant stoppages. In some cases, it costs more than 100 yen.

The purpose of the present invention is to improve the resistance of marine organisms, especially mussels and snails, which are found in large quantities at many power plants, without using drugs or heavy metals that affect the marine ecology. It is an object of the present invention to provide a non-polluting and highly effective method for preventing the adhesion of marine organisms and a ball cleaning device during the vulnerable larval stage.

[Means to solve the problem]

In the present invention, warm water is periodically injected into marine organisms when they are larvae.

Furthermore, the present invention provides for periodic injection of cold water during the larval stages of marine life.

Furthermore, the present invention injects seawater with high or low salinity when marine organisms are larvae.

Additionally, the present invention allows for periodic injection of hot or cold water into the ball circulation system.

[For production]

According to the present invention, by regularly injecting hot or cold water (or lowering or increasing the concentration of salt water), adherent larval plankton such as mussels and Fujibbo are killed, so marine life is always kept alive. No adhesion will occur.

Furthermore, according to the present invention, when hot water is injected into the outlet side of the ball circulation system, the hot water is introduced into a heat exchanger such as a condenser, but the amount of hot water injected is very small compared to the amount of cooling water of the heat exchanger. Since hot water is injected intermittently, the effect on the efficiency of the heat exchanger is negligible, and there is no impact on the environment.

〔Example〕

As an example of the present invention, a description will be given below regarding the mussel, which has the most adverse effect on the effectiveness of hot water or cold water on marine organisms as an adherent marine organism.゛In particular, sponge ball cleaning equipment circulates sponges inside the piping, so the occurrence of mussels can reduce the cleaning ability, and in the worst case, the sponge balls may remain stuck inside the piping. Therefore, it is necessary to remove mussels when they are still young.

The maximum shell length of members of the mussel can reach approximately 90 mm, and it is one of the largest obstacles to the seawater system.Mature mussels lay eggs in seawater, disseminate eggs, and fertilize in the seawater. Spawning is at its peak from winter to spring, and the seawater temperature inhabits a wide range of about 1θ to 20℃. Approximately 10 hours after fertilization, they become floating larvae called trokotsuoa larvae, which swim around in the water. 40 to 70 hours after fertilization, a transparent, round-shaped shell is secreted from the shell gland and becomes a D-type larva.

After this, a second shell is secreted from the mantle, becomes an apical larva, then a metamorphic larva, attaches to the substrate, and metamorphoses to become a larva. This is the primary attachment stage.

This is approximately 16 to 20 days after fertilization. Once the shell is formed, the shell becomes more resistant to sudden changes in the habitat as it closes and prevents changes.

Therefore, it is easier to carry out adhesion suppression treatment during the period of floating larvae than the fertilized eggs before attachment.

And it is highly effective.

Regarding the ecology of the blue mussel, fertilized eggs and floating larvae of the blue mussel were reared for a certain period of time (72 hours) under different conditions of water temperature and salinity (seawater concentration), and the survival rate under each condition was determined in Table 1. FIG. 3 shows a correlation diagram of temperature and salinity tolerance drawn by computer based on Table 1.

For the purpose of suppressing adhesion, a survival rate of about 10% or less can be achieved by setting the temperature and salinity outside the outermost curve in FIG.

Table 1 (Note)...The numbers in parentheses indicate the salt concentration (%I: Vermil).

A noteworthy fact in Table 1 is that if the salt concentration is changed beyond a certain level, a suppressive effect can be obtained by changing the temperature slightly from room temperature.

In other words, in 100% seawater (salinity: about 35 per mil), the survival rate is 60% at a water temperature of 12 degrees Celsius, but at a salinity of about 20‰ (per mil) and about 40‰
(Permil), it decreases to about 4%.

Also, the effect on the temperature increase side is large, at 30°C.

All of them die regardless of the salinity concentration. Previously about 4
While the method of heating to a high temperature of 0℃ or higher is adopted,
Effective at much lower temperatures.

In this way, even when using a pest control method that raises the temperature, the temperature is lower than conventional methods, so the heated waste water from the in-house cooling water system can be used as a heat source, and by injecting it into the ball cleaning device, it is possible to reduce the salinity of seawater. Since it can be reduced, it is possible to achieve effects from both the temperature and salinity aspects.

In addition, one possible way to lower the temperature is to use a water cooler, but in winter the air temperature is on average lower than the seawater temperature, and the temperature of the freshwater in the facility is close to the air temperature, so it is recommended to use it as is. It is also quite possible.

In this way, when injecting hot or cold water, if you try to change the temperature of seawater while it is flowing, you will need to inject a fairly large proportion of the seawater flow rate, and various chemical reactions will occur. It is not a good idea to consume a large amount of treated in-house water because it increases economic loss.

On the other hand, when operating a ball cleaning device, we focused on the fact that the time when the balls are not circulating is overwhelmingly longer than the ball circulation time, and the timing of injection of hot or cold water is determined so that the ball circulates with good replacement efficiency by the injected water. This shall be carried out during suspension. According to such an injection method, the stagnant portion within the system is also replaced with the injected water, so that the adhesion suppressing effect is exerted on all parts within the system.

Next, embodiments of the present invention will be described with reference to FIGS. 1, 2, and 5 to 9.

FIG. 1 shows an example in which a hot water injection system according to the present invention is added to the conventional system shown in FIG. 4 (although FIG. 1 is a simplified diagram, it is the same as FIG. 4). In the added hot water injection system, water is introduced from a raw water supply system 21 to a water heater 12 having a heater 23 that heats the raw water, passes through a hot water pump 13 that supplies hot water to the ball circulation system, and then is connected to the ball circulation pump inlet valve 8. There is an orifice 1 in the system that is connected to the upstream and downstream sides and ensures a constant flow rate of hot water.
It consists of 4°15 and ascending order of 16 to 19.22.

Next, the operating method in this embodiment will be explained using FIG. 2.

In the ball cleaning device, the ball circulation stop time is overwhelmingly longer than the ball circulation time, so hot water injection is carried out during the ball circulation stop, when the injection water has a good replacement efficiency.

While the ball circulation is stopped (during the OFF period of the circulation pump 6), the raw water is supplied from the raw water supply system 21 to the water heater 12 via the raw water supply valve 22, and is raised to a predetermined temperature by the heater 23. As mentioned above, the predetermined temperature is 30° C., which is the temperature at which marine organisms die when they are larvae.

The temperature is set at 30℃+α) in consideration of heat radiation from hot water injection piping. The hot water raised to a predetermined temperature is injected into the ball circulation system by operating the hot water pump 13 when injection is necessary.
At this time, by closing the valve 8 of the ball circulation system, hot water is introduced into two systems, that is, one system is led to the main pipe inlet system 2 via the ball circulation pump 6 and the ball recovery device 7, and the other system
The system is led to the main pipe outlet system 4 via the ball collector 5, and hot water is injected into the entire ball circulation system. Furthermore, the second
In the diagram, ball circulation operation → stop ball circulation operation → hot water injection →
Although the procedure is described as supplying raw water and heating, the procedure may be as follows: ball circulation operation → stop ball circulation operation → raw water supply and heating → hot water injection. Further, the hot water injection point is not limited to the above, but wet water is always introduced to the main pipe population system 2 and the main pipe outlet system 4. The orifices 14 and 15 are installed to ensure a constant flow rate of hot water, and the check valve 18 is installed to prevent seawater from flowing back toward the water heater 12 side.

This hot water injection does not require constant water injection, and based on the experimental results, it is considered that injection frequency is once every 7 days while the ball circulation is stopped, and injection time of 1 hour/about the same is sufficient.

FIG. 5 shows an embodiment in which cold water is used instead of hot water.

As mentioned earlier, experiments have shown that cold water has the effect of preventing the adhesion of marine organisms, and marine bacteria generally do not survive at low temperatures (44°C).
℃), life activity is said to cease.

Therefore, by using the water cooler 24 instead of the water heater shown in FIG. 1 and injecting cold water into the ball circulation system, the effect of preventing shellfish adhesion can be achieved.

FIG. 6 shows an embodiment in which the hot water injection method shown in FIG. 1 and the cold water injection method shown in FIG. 5 are combined to achieve the effect of preventing the attachment of marine organisms. The operating procedure in this case is to utilize the temperature difference between seasons, i.e., when the raw water is relatively high temperature (summer, etc.), a water heater is used, and when the raw water is relatively low temperature, a water heater is used. (During winter, etc.), using a water cooler is economically advantageous in terms of operating costs.

FIG. 7 is a modification of the embodiment shown in FIG. 1, in which heated waste water from the in-house cooling water system 25 is used as a heat source for hot water, and the temperature of the heated waste water from the in-house cooling water system reaches a predetermined level. If the temperature has not been reached and heating is required, a water heater will be used, but if heating is not necessary, equipment such as a water heater is not required.

FIG. 8 shows a modification of the embodiment shown in FIG.
A bypass system 26 is installed, so that when the raw water is below a predetermined temperature depending on the season, the water cooler 24 is bypassed and cold water is injected, and when the raw water is above a predetermined temperature, the water cooler 24 can be used. It is something.

Figure 9 is a modification of the embodiment shown in Figure 6, and is an implementation in which the most economical operation can be selected between seasons by applying the embodiments shown in Figures 7 and 8. This is an example.

Furthermore, in addition to hot water and cold water, the salt water concentration according to Table 1,
It is possible to remove young molluscs even if the amount is 20 bamil or less or 40 bamil or more.

C Effects of the Invention] According to the present invention, marine organisms, especially mussels, Fujibo, etc., which are found to be attached in large quantities at many power plants, etc., can be treated without using drugs or heavy metals that may affect the ecology of the coast. It is possible to obtain a non-polluting and highly effective effect of preventing the adhesion of marine organisms in the larval stage when the resistance is weak. Further, according to the present invention, there is an effect that functional failure of the hole cleaning device can be prevented. Therefore, there is an effect that contributes to improving the performance and reliability of the heat exchanger and the entire plant.

Further, according to the present invention, especially when hot water is injected into the outlet side of the ball circulation system, the hot water is introduced into a heat exchanger such as a condenser, but the amount of hot water injected is equal to the amount of cooling water of the heat exchanger. Since the amount of hot water is small and intermittently injected, the effect on heat exchange efficiency is negligible, and there is no effect on the environment.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the hot water injection method of the present invention, and FIG. 2 is a diagram showing an embodiment of the operating procedure according to FIG.
Figure 3 is a diagram showing the experimental results of temperature and salinity tolerance of mussel larvae, Figure 4 is a diagram showing a general conventional ball cleaning system, and Figure 5 is an example of the cold water injection method of the present invention. FIGS. 6 to 9 are diagrams showing other embodiments of the present invention. 1... Main tube pump, 2... Main tube inlet system, 3...
Heat exchanger, 4... Main tube outlet system, 5... Ball collector, 6... Ball circulation pump, 7... Ball collector, 8-11... Valve, 12... Water heater, 13... Hot water pump, 14-15... Orifice, 16-17.
... Valve, 18... Check valve, 19-20... Valve. 21...Raw water supply system, 22...Valve, 23...Heater, 24...Water cooler, 25...In-house cooling water system. Figure 3

Claims (1)

[Claims] 1. In a seawater system of a plant that uses seawater,
A method for preventing marine organisms from adhering to a seawater system, which comprises periodically injecting freshwater whose temperature is set to a temperature higher than °C into the seawater system to prevent marine organisms from adhering to the seawater system at the larval stage. 2. In the seawater system of a plant that uses seawater, 5℃
A method for preventing the adhesion of marine organisms in a seawater system, which comprises periodically injecting freshwater at the following temperature into the seawater system to prevent the adhesion of marine organisms at the larval stage. 3. In the seawater system of a plant that uses seawater, the salinity of the seawater is set to 40‰ (per mil) or more to prevent attachment of marine organisms at the larval stage. Method for preventing biofouling. 4. In the seawater system of a plant that uses seawater, the salt concentration of seawater is kept below 20‰ (per mil) to prevent attachment of marine organisms at the larval stage. Method for preventing biofouling. 5. In ball cleaning equipment installed to remove dirt on the inner surfaces of the thin tubes of tubular heat exchangers such as condensers and seawater coolers that use seawater as cooling water, hot water is periodically supplied to the ball circulation system. A ball cleaning device characterized by having a hot water system for injecting water into the bowl. 6. In ball cleaning equipment installed to remove dirt on the inside of the thin tubes of tubular heat exchangers such as condensers and seawater coolers that use seawater as cooling water, cold water is periodically supplied to the ball circulation system. A ball cleaning device characterized by having a cold water injection system. 7. A heat exchanger, a first system that sends cleaning balls together with cooling water made of seawater to the heat exchanger during cleaning, and a system that cools the cleaning balls discharged through piping in the heat exchanger. a second system that sends out the water together with the water; a collector that collects the cleaning balls from the second system; a pump that takes in and discharges the collection balls from the collector through a valve; a collector for collecting cleaning balls discharged from the pump; and a collector for collecting the cleaning balls discharged from the pump;
A water passage means provided either in the first system or the second system or before or after the pump, and hot water (
or cooling water); and a ball cleaning device. 8. A heat exchanger, a first system that sends cleaning balls together with cooling water made of seawater to the heat exchanger during cleaning, and a system that cools the cleaning balls discharged through piping in the heat exchanger. A second system that sends water out together with water, a ball collector that collects cleaning balls from the second system, and a pump that takes in and discharges the collected balls from the ball collector through a valve. , a collector for collecting the cleaning balls discharged from the pump, a water passage means provided before and after the valve, and a water passage means for the water passage when the pump is stopped and the valve is closed. A ball cleaning device comprising means for introducing hot water (or cooling water). 9. The ball cleaning device according to claim 8, wherein the water passage means provided before and after the valve each include an orifice.