JP2003183866A - Method for preventing organism fouling and corrosion in water conveyance line, and device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing organism fouling and corrosion which can simply, economically and reliably prevent both of fouling caused by adhesion and growth of organisms and corrosion of metal parts, in a water conveyance line such as a seawater cooling line on a power plant or ironworks, and a device therefor. <P>SOLUTION: This method is characterized by simultaneously or alternately supplying ferrous ions from an iron electrode 1 into water and supplying copper ions from a copper electrode 2 into the water, at a part of the water conveyance line, by electrolysis by using of the iron electrode 1, the copper electrode 2, and a cathode material 3, to prevent fouling due to adhesion of organisms and corrosion of the metal parts, on the downstream side of the water conveyance line. An electrolysis between the iron electrode 1 and the copper electrode 2 by alternately changing the polarity, eliminates the need for the cathode material 3, which enables an easier and more economical implementation. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents corrosion of metal parts such as heat exchangers and condensers in water transmission lines such as seawater cooling lines in power plants and steelworks, and at the same time prevents stains due to adhesion of living organisms. A method and an apparatus thereof.

[0002]

2. Description of the Related Art In seawater cooling lines of thermal power plants, hydroelectric power plants, steel mills, etc., along with corrosion of metal parts such as heat exchangers and condensers, marine organisms adhere to and grow on the inner surfaces of pipes, etc. Is likely to occur. This problem is the same when taking freshwater from lakes and rivers. If this corrosion or biofouling is left untreated, it will cause serious damage to the operation management of the plant.

Conventionally, an electrocorrosion method has been generally used as a method for preventing corrosion of heat transfer tubes and tube plates of heat exchangers and condensers. That is, electricity is applied to the cathode from the iron electrode that is the anode,
By supplying iron ions into water by electrolysis of an iron electrode, a corrosion-resistant iron-based protective coating is formed on the surface of a heat exchanger, a compound water container, or the like made of a copper alloy or the like to improve the corrosion resistance.

The cathodic protection method for preventing the corrosion of the metal part by supplying the iron ions has already been used in many cases and is one of the effective anticorrosion methods. However, this cathodic protection method has no biological antifouling effect, that is, an effect of preventing organisms contained in water taken in from the sea or lake from adhering to and growing on the inner surfaces of equipment and piping.

On the other hand, as a method for preventing biofouling due to the adherence and growth of organisms on the inner surfaces of heat exchangers, condensers, pipes, etc., (1) workers regularly clean marine organisms attached to them. A method of removing, (2) a method of applying an antifouling paint to the inner surface of a pipe or the like to prevent the adhesion of marine organisms, (3) a method of removing marine organisms adhered by passing a sphere inside the pipe, (4) There are known methods for preventing the adhesion of marine organisms by generating sodium chlorite by electrolysis of water.

However, the method (1) requires a lot of human power,
The cost of disposing of the collected organisms is large, and there is also a loss due to suspension of operation, resulting in poor economic efficiency.
Since the method (2) has a short duration of the biological antifouling effect of 3 to 4 years, it requires regular repainting of the paint, which is disadvantageous in economic efficiency and antifouling performance. The method (3) has a problem that the removed marine organisms and the introduced balls block the heat transfer tubes and pipes of the heat exchanger. In addition, it is difficult to obtain a sufficient antifouling effect with sodium hypochlorite by the method of (4), and it is necessary to increase the chlorine concentration in order to reliably prevent adherent growth of organisms, which is desirable from an environmental point of view. It cannot be called a method.

[0007]

As described above, although an effective anticorrosion method has been known in a water guiding line such as a seawater cooling line, it is difficult to prevent biofouling due to adherent growth of organisms. Therefore, the adhered growth of organisms is likely to progress, and the efficiency of heat exchangers, condensers, etc., and obstacles such as clogging of pipes are likely to occur.

The present invention has been made in view of such conventional facts.
Biological antifouling that can easily and economically and reliably prevent both fouling due to adherent growth of organisms and corrosion of metal parts in water transmission lines such as seawater cooling lines in power plants and steelworks over a long period of time. It is an object to provide an anticorrosion method and an apparatus therefor.

[0009]

In order to achieve the above object, the first biofouling prevention / corrosion prevention method provided by the present invention is an iron electrode, copper in water in a part of a water conveyance line for taking in seawater or freshwater. An electrode, and a step of immersing the cathode material, supplying a DC current from the iron electrode to the cathode material to supply iron ions into the water, and a step of supplying a DC current from the copper electrode to the cathode material to supply the copper ions into the water, By performing both steps simultaneously or alternately, it is possible to prevent fouling due to biofouling and corrosion of metal parts in the water guiding line on the downstream side.

A second biological antifouling provided by the present invention
The anticorrosion method is a step of immersing the iron electrode and the copper electrode in water in a part of the water conveyance line that takes in seawater or fresh water, supplying a direct current from the iron electrode to the copper electrode to supply iron ions into the water, and Having a step of supplying a direct current to the iron electrode to supply copper ions into the water, by performing both steps alternately,
A feature of the present invention is that it prevents fouling due to biofouling and corrosion of metal parts in the water guide line on the downstream side.

In the above-mentioned first and second biological antifouling and anticorrosion methods according to the present invention, the concentration of iron ions supplied to water is 5 to 40 ppb, and the concentration of copper ions is 10 to 10.
It is characterized by maintaining at 40 ppb.

The first biological antifouling / corrosion preventive apparatus provided by the present invention is a DC power supply, which includes an iron electrode, a copper electrode, and a cathode material, which are mutually insulated by an insulating material, in a water conduit for taking in seawater or fresh water. And a device for supplying electric current from the DC power supply device to the cathode material via the iron electrode and / or the copper electrode, thereby preventing the contamination and the corrosion of the metal part due to the biological adhesion in the water guiding line on the downstream side. And

The second biological antifouling provided by the present invention
The anticorrosion device is installed in the water conveyance line that takes in seawater and fresh water.
An iron electrode and a copper electrode mutually insulated by an insulating material, a DC power supply device, and a power supply switching means for switching the connection of the DC power supply device between the iron electrode and the copper electrode are provided, and the iron electrode is removed from the DC power supply device. By flowing an electric current to the copper electrode via the copper electrode or to the iron electrode via the copper electrode, it is possible to prevent fouling due to biological attachment and corrosion of the metal part in the water guiding line on the downstream side.

In the above-mentioned first and second biological antifouling / corrosion preventing devices according to the present invention, the iron electrode and the copper electrode are
It is characterized in that it is replaceably installed in an openable / closable electrode box or tank installed in a water conveyance line, or installed in an intake channel of a water intake facility in contact with seawater or fresh water.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention simultaneously prevents both corrosion of metal parts in a water conduit and fouling due to biofouling by the same electrochemical method. That is, by combining the cathodic protection method of supplying iron ions into water from the iron electrode by electrolysis and the method of preventing biological fouling by supplying copper ions into water from the copper electrode by electrolysis, the same operation is simple. In addition, a reliable effect can be obtained economically and over a long period of time.

The method and apparatus according to the present invention will be described in detail with reference to the drawings. 1 and 2 show a first biofouling / corrosion preventive device of an electrode box type (pipe type) installed in a seawater cooling line. In this device, an electrode box 5 having an openable / closable lid 6 is provided in the middle of a water conduit (not shown) of a seawater cooling line, and an iron electrode 1 and a copper electrode 6 fixed to the lid 6 via an insulating material 4 are provided. The electrode 2 and the cathode material 3 are arranged in the electrode box 5. Each connection terminal of the iron electrode 1, the copper electrode 2 and the cathode material 3 is connected to the secondary side terminal of an external DC power supply device (not shown) in each connection box 7.

The purity and shape of the iron electrode 1 and the copper electrode 2 are not particularly limited, and commercially available iron plate or iron rod, copper plate or copper rod or the like can be used. The material of the cathode material 3 is also not particularly limited as long as it is conductive, but it is desirable to use stainless steel so as not to corrode when power is not supplied. Further, the electrode box 5 can also serve as the cathode material, in which case it is not necessary to install a separate cathode material. Iron electrode 1
And the copper electrode 2 is gradually consumed by using,
The electrode 6 can be easily replaced by opening the lid 6 of the electrode box 5 after use for a certain period of time.

Although the positions of the iron electrode 1 and the copper electrode 2 are the iron electrode on the seawater inlet side and the copper electrode on the outlet side in FIG. 1, they are not particularly limited, and the copper electrode and the outlet are located on the inlet side. The side may be an iron electrode, or the copper electrode and the iron electrode may be arranged in parallel.

In the first biological antifouling / corrosion prevention method using the above apparatus, a direct current is passed from the DC power supply through the iron electrode 1 and / or the copper electrode 2 to the cathode material 3 to electrolyze the seawater. Supply iron ions and / or copper ions.
By supplying iron ions, a corrosion-resistant iron-based protective coating is formed on the surface of the metal parts made of copper alloy or other heat exchangers, condensers, etc. located downstream of the iron ions, which can improve the corrosion resistance of the metal parts. it can. At the same time, since copper ions supplied to seawater are toxic to living organisms, it is possible to prevent the growth and reproduction of living organisms in the seawater cooling line. The concentrations of iron ions and copper ions can be controlled by the amount of current passed.

The concentration of iron ions supplied to seawater is 5 to 5.
Keep at 40 ppb. However, when the heat exchanger is washed, the protective film is lost, so iron ions are supplied at a concentration of 25 to 35 ppb for the reformation of the iron-based protective film for about one month after cleaning. Preferably. After that, it is preferable to set the iron ion concentration to about 5 to 10 ppb in order to suppress the consumption of the iron electrode and prevent the cost from increasing.

The concentration of copper ions supplied to seawater is maintained at 10 to 40 ppb. However, especially in the summer (April-September) when the marine life grows, it is supplied at a high concentration of about 25-30 ppb, and in winter (October-March) when there is almost no growth, the consumption of the copper electrode is reduced. Therefore, in order to suppress the load on the environment, it is preferable to set the concentration as low as about 10 to 15 ppb.

In the first biofouling / corrosion prevention method, the supply of iron ions for corrosion protection and the supply of copper ions for biofouling can be carried out simultaneously or alternately. Further, while the iron ion supply and the copper ion supply are performed simultaneously or alternately, the operation is usually performed continuously, but may be performed intermittently. Intermittently means, for example, a case where iron ions and copper ions are simultaneously supplied, but the supply of both ions is temporarily stopped at a predetermined time interval.

Next, as a second biological antifouling / corrosion prevention device,
FIG. 3 and FIG. 4 show an electrode switching type device by an electrode box type (pipe type) installed in a seawater cooling line. In this electrode switching type device, a water pipe (not shown) of the seawater cooling line
An electrode box 5 having a lid 6 that can be opened and closed is provided in the middle of the box, and an iron electrode 1 and a copper electrode 2 fixed to the lid 6 via an insulating material 4 are arranged in the electrode box 5. Further, in order to switch the polarities of the electrodes, a power supply switching means (not shown) for switching the connection of the DC power supply device (not shown) between the iron electrode 1 and the copper electrode 2 is provided.

The connection terminals of the iron electrode 1 and the copper electrode 2 are
Each is connected to the secondary side terminal of the external DC power supply device in each connection box 7. The material and arrangement of the iron electrode 1 and the copper electrode 2 and the replacement of the electrodes are the same as in the case of the first device.

In the biological antifouling / corrosion prevention method using the second device, the polarities of the iron electrode 1 and the copper electrode 2 are switched by the power source switching means, that is, when iron ions are supplied, the iron electrode 1
As the anode and the copper electrode 2 as the cathode, and when supplying copper ions, the copper electrode 2 as the anode and the iron electrode 1 as the cathode,
Energize each. Therefore, the supply of iron ions for anticorrosion and the supply of copper ions for biofouling must always be performed alternately and cannot be performed simultaneously. Further, the operation can be performed continuously or intermittently while alternately supplying the iron ions and the copper ions.

Also in the second method, the corrosion resistance of the metal portion arranged downstream can be improved by supplying iron ions, and the growth and reproduction of organisms can be prevented by supplying copper ions. The concentrations of iron ions and copper ions are the same as in the case of the first method, and can be controlled by the amount of current to be applied. In addition, the period of polarity switching is not particularly limited, and iron ions and copper ions are supplied at an appropriate concentration in view of their respective effectiveness, so that the anticorrosion and biological antifouling effects are economically and effectively exhibited. It becomes possible.

According to the electrode switching type second device and the second method, the non-switching type first device and the first method are used.
Compared with the method described above, the device is simpler because no cathode material is required, and since the polarities of the iron electrode 1 and the copper electrode 2 are alternately switched and used, the consumption of the electrode is small and the power consumption can be saved. There are advantages.

FIG. 5 shows another specific example of the biological antifouling / corrosion preventive apparatus of the present invention, which is an apparatus of a tank type electrode box type. In this device, an iron electrode box 5a and a copper electrode box 5b are installed in parallel in the middle of the water conduit 8 in the water guiding line, and the iron electrode box 5a includes the iron electrode 1 and the copper electrode box 5b. Is provided with a copper electrode 2 and a cathode material 3. When the electrodes are consumed, the iron electrodes 1 and the copper electrodes 2 can be easily replaced by opening the lids 6a and 6b installed on the respective electrode boxes 5a and 5b.

In the apparatus shown in FIG. 5, the iron electrode box 5a is arranged upstream of the copper electrode box 5b, but the arrangement of both is not particularly limited, and either of them is the upstream side. Is also good. Also in the case of this tank type electrode box, the copper electrode box 5b can also serve as the cathode material. Furthermore,
By arranging the iron electrode and the copper electrode in one electrode box and providing the power source switching means, the electrode switching type device can be used in which the polarities of both electrodes are switched and used.

FIGS. 6 and 7 show another specific example of the biological antifouling / corrosion preventive apparatus of the present invention, which is an intake channel type apparatus. In the intake channel type device, as can be seen from FIG. 6 showing the entire intake channel, an electrode plate assembly 10 composed of iron electrodes, copper electrodes, etc.
Since it is installed in the intake channel 11 of the intake facility, it is possible to exert a wide range of effects on the downstream side. A bar screen 13 and a traveling screen 14 for removing dust, driftwood, etc. in seawater are arranged near the water intake 12 of the water intake passage 11, and an intake pump 15 for sending seawater to the water conduit 8 is provided downstream thereof. Is attached. The electrode plate assembly 10 is preferably a bar screen 13 and a traveling screen 1.
Place between 4.

In the electrode plate assembly 10, for example, as shown in FIG. 7, a plurality of iron electrodes 1 and copper electrodes 2 are alternately arranged, and a cathode plate 3 is provided between each iron electrode 1 and copper electrode 2. They are arranged and held by the fixing plate 9 via the insulating material 4 respectively. The upper fixing plate 9 is provided with connection boxes 7 for connecting the respective connection terminals of the iron electrode 1, the copper electrode 2 and the cathode material 3 to the secondary side terminals of an external DC power supply device (not shown). is there. It is necessary to leave a space between each iron electrode 1, the copper electrode 2, and the cathode material 3 to such an extent that water intake is not hindered.
Further, the electrode plate assembly 10 is installed in the intake channel 11 in a direction substantially perpendicular to the flow of seawater.

[0032]

[Embodiment] A first apparatus (non-switching type) shown in FIGS. 1 and 2 as a biological antifouling / corrosion preventing apparatus using an electrode box type (pipe type)
And a second device (electrode switching type) shown in FIGS. 3 and 4, seawater sucked up by a circulation pump from a plastic hose is monitored by a copper alloy through the above-mentioned biological antifouling / corrosion preventive devices. After introducing water into the tank, a test was conducted to discharge it into the sea.

That is, the first device of FIGS. 1 and 2 (non-switching type)
Then, a direct current was made to flow from the DC power supply device to the cathode material 3 via the iron electrode 1 and the copper electrode 2, and iron ions and copper ions were simultaneously supplied into seawater. On the other hand, in the second device (switchable type) of FIGS. 3 to 4, the power source switching means switches the polarities of the iron electrode 1 and the copper electrode 2 every week, and the iron electrode 1 is used as the anode and the copper electrode 2 is used as the cathode. The operation of supplying iron ions and the operation of supplying copper ions using the copper electrode 2 as an anode and the iron electrode 1 as a cathode were alternately performed.

These tests were continuously carried out for one year from February, and the iron ion concentration and the copper ion concentration supplied to seawater were controlled as shown in Table 1 below by changing the energization amount. After the completion of the test, the corrosion state in the monitoring tank and the adhesion state of marine organisms were observed, and the results are also shown in Table 1 below. In Table 1, those in which no corrosion was observed in the tank were indicated by ◯, and those in which corrosion was observed were indicated by x. In addition, those with no organisms attached were ○,
A sample showing a very small amount of biofouling was shown by Δ, and a sample showing a large amount of biofouling was shown by x.

[0035]

[Table 1]

Test N using the first device (non-switching type)
In o.1, as a result of operating by increasing the iron ion concentration for one month only in February immediately after the start of the test and increasing the copper ion concentration in the summer of April to September, the inside of the monitoring tank was corroded. And no biofouling was observed. Also, the test No. 2 using the same first device (non-switching type)
Although the fluctuations in the iron ion concentration and the copper ion concentration were made smaller than those in Test No. 1, corrosion and biofouling were not observed on the inner surface of the tank due to sufficient supply.

Test No. using the second device (switchable type)
In No. 3, in February immediately after the start of the test, only iron electrolysis was performed for one month to supply only iron ions, and thereafter, copper ions and iron ions were alternately supplied every week. The iron and copper ion concentrations to be supplied were slightly lower than those of Test No. 1, but the copper ion concentration was increased during the summer months of April to September. As a result, no corrosion or biofouling was observed on the inner surface of the monitoring tank.

On the other hand, using the first device (non-switching type), the test N of the comparative example in which copper ions were not supplied at all for one year
In o.4, a large amount of biofouling was observed. Also, using the same device, iron and copper ions were supplied simultaneously,
In Test No. 5 of the comparative example in which the concentrations were set low, corrosion was confirmed on the inner surface of the monitoring tank, and a small amount of biofouling was also confirmed.

[0039]

EFFECTS OF THE INVENTION According to the present invention, both the fouling due to the adherent growth of organisms and the corrosion of metal parts in a water-conducting line such as a seawater cooling line of a power plant or an iron mill are performed by using the same electrolysis electrochemical method. With a simple device, iron ions from the iron electrode and copper ions from the copper electrode can be supplied simultaneously or alternately and can be easily and economically and reliably prevented for a long period of time.

Further, it is almost unnecessary to stop the operation for removing the attached organisms, and the iron electrode, the copper electrode, etc. can be replaced, and the apparatus can be automated to operate without requiring human labor. is there. Furthermore, by switching the polarities of the iron electrode and the copper electrode, the consumption of the electrode can be reduced, the power consumption can be saved, and the device can be made compact, which is more economical.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view showing a specific example of a non-switching type electrode box type (piping type) biological antifouling / corrosion preventive apparatus according to the present invention.

2 is a cross-sectional view of the device of FIG. 1, (a) is a cross-sectional view taken along the line AA, and (b) is a cross-sectional view taken along the line BB.

FIG. 3 is a side view showing a cutaway example of a specific example of the switchable electrode box type (pipe type) biological antifouling / corrosion preventive apparatus according to the present invention.

4 is a cross-sectional view of the device of FIG. 3 along the line AA.

FIG. 5 is a non-switching type electrode box type (tank type) according to the present invention.
It is the side view which notched and shown one specific example of the biological antifouling / corrosion prevention apparatus of this.

FIG. 6 is a non-switching type intake channel type biological antifouling system according to the present invention.
It is the side view which notched and showed one specific example of the anticorrosion apparatus.

7 is a cross-sectional view showing an electrode assembly of the device of FIG.

[Explanation of symbols]

1 Iron electrode 2 Copper electrode 3 Cathode material 4 insulation 5 electrode box 7 connection box 8 water conduit 10 electrode assembly 11 Intake channel 13 bar screen 14 Traveling screen 15 Water intake pump

Claims (7)

[Claims] 1. A step of immersing an iron electrode, a copper electrode, and a cathode material in water at a part of a water-conducting line for taking in seawater or fresh water, and applying a direct current from the iron electrode to the cathode material to supply iron ions into the water. And a step of supplying a copper current into the water by flowing a direct current from the copper electrode to the cathode material, and by performing both steps simultaneously or alternately, contamination and metal due to biofouling in the water conveyance line on the downstream side thereof. A biofouling / corrosion prevention method for a water conveyance line, which is characterized by preventing corrosion of a part. 2. A step of immersing an iron electrode and a copper electrode in water at a part of a water-conducting line for taking in seawater or fresh water, supplying a direct current from the iron electrode to the copper electrode to supply iron ions into the water,
There is a step of supplying a direct current from the copper electrode to the iron electrode to supply copper ions into the water, and by alternately performing both steps, contamination due to biofouling and corrosion of metal parts in the water conveyance line on the downstream side can be performed. A biofouling / corrosion prevention method for water conduits that is characterized by prevention. 3. The concentration of iron ions supplied to water is 5 to 4
The method for biofouling / corrosion prevention of a water conveyance line according to claim 1 or 2, characterized in that the concentration of copper ion is maintained at 0 ppb and the concentration of copper ion is maintained at 10-40 ppb. 4. An iron electrode, a copper electrode, and a cathode material, which are insulated from each other by an insulating material, and a direct current power supply device are provided in a water conduit for taking in seawater or fresh water, and the direct current power supply device supplies the iron electrode and / or A biological antifouling / corrosion preventive device for a water guiding line, characterized in that by applying an electric current to a cathode material through a copper electrode, the water guiding line on the downstream side thereof is prevented from being contaminated by living organisms and from corroding metal parts. 5. An iron electrode and a copper electrode, which are mutually insulated by an insulating material, a direct current power supply device, and a direct current power supply device connected between the iron electrode and the copper electrode in a water conduit for taking in seawater or fresh water. And a power source switching means for switching, and by supplying a current from the DC power supply device to the copper electrode via the iron electrode or to the iron electrode via the copper electrode, contamination and metal parts due to biological attachment in the water guiding line on the downstream side thereof. A biofouling / corrosion preventive device for water transmission lines, which is characterized by preventing corrosion of water. 6. The water guiding line according to claim 4, wherein the iron electrode and the copper electrode are replaceably mounted in an openable / closable electrode box or tank installed in the water guiding line. Biological antifouling / corrosion prevention equipment. 7. The biological protection system for a water conveyance line according to claim 4, wherein the iron electrode and the copper electrode are installed in a water intake channel of a water intake facility so as to be in contact with seawater or fresh water. Antifouling / corrosion protection device.