JPH0368957B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for preventing corrosion of a heat exchanger, and in particular to a method for preventing corrosion of a heat exchanger, and in particular, a heat exchanger using steel alloy pipes as cooling pipes and seawater as cooling water. The present invention relates to a suitable method for preventing corrosion of vessels.

[Prior art]

Regarding the technology to prevent cooling pipes by implanting iron ions, see "Thermal Nuclear Power Generation" Vol. 26-No. 10,
Oct. 1975 "Study on the formation of anticorrosion film on condenser tubes" pages 1113-1116 for details.

From many of the above-mentioned documents, the ferrous sulfate injection method, the natural iron dissolution method, and the iron electrolysis method are known.

The ferrous sulfate injection method is a method in which ferrous sulfate is injected into cooling seawater to supply iron ions to copper cooling pipes and form an iron-based protective film. Injecting chemical liquids into things is problematic from the standpoint of environmental conservation, and its use is gradually becoming obsolete. In addition, as shown in Figure 2, the natural iron elution method involves immersing an iron piece 16 into a cooling water system or into a system that flows into the cooling water system to elute iron ions, which are then introduced into a heat exchanger to prevent corrosion. However, since the elution rate of iron ions is very slow, the iron ion supply device must be very large in order to elute a sufficient amount of iron ions, making it impractical and not generally employed.

From the above, the iron electrolysis method can be considered as the most common method. In this method, as shown in Figure 3, iron pieces in the iron ion supply device or in the cooling water system are used as cathodes and anodes to electrolyze iron to generate iron ions, which are then guided to a heat exchanger for copper-based cooling. Although this method forms a protective coating on the tube, it has economic drawbacks such as requiring an expensive external power supply to electrolyze the iron and constantly consuming a large amount of power.

Therefore, the present inventor first proposed a more economical and superior method of eluting enough iron ions to protect the cooling tube, by introducing iron and a natural potential nobler than iron into the iron ion supply device. By mixing metals such as titanium, copper, and stainless steel, and using iron as a sacrificial electrode, a large amount of iron ions are generated.
We created a method for preventing corrosion of heat exchangers, which is characterized by supplying this to the copper-based cooling pipes of heat exchangers (hereinafter referred to as a "proposal").

[Problem that the invention seeks to solve]

After completing the invention related to the above-mentioned draft, the present inventor further carried out practical tests and improvement research, and pursued the development of a technology that promotes the elution of iron ions.

[Means for solving problems]

The above research can be summarized as follows.
In the corrosion prevention method according to the earlier application, iron pieces and
Metal materials nobler than iron are mixed in the ion supply device, but in practical use, at least one point of these dissimilar materials with different potentials should be electrically connected to each other, and the other end should be connected to each other through cooling water. It was confirmed through experiments that forming a closed circuit between iron and a dissimilar material having a higher potential than iron by facing each other is effective in accelerating the dissolution rate of iron. In addition, materials having a natural potential nobler than iron include not only dissimilar metals such as copper, stainless steel, and titanium specified in the prior invention, but also nonmetallic materials such as carbon having a natural potential nobler than iron. It has also been confirmed that it can be used satisfactorily for this purpose.

Furthermore, it was confirmed that the dissolution rate of iron ions was greatly accelerated by placing a magnet at the entrance of the iron ion supply device and magnetizing the cooling water at the entrance of the device. Established dissolution technology.

In order to improve the proposed corrosion prevention method based on the above research results and further promote the elution of iron ions, the corrosion prevention method of the present invention includes an iron ion supply device using a natural solution method in the cooling water flow path. At the same time, an iron member and a member made of a material more noble than iron are charged into the iron ion supply device, and the elution of iron ions from the iron member is promoted by the material nobler than iron, and The iron member and the member made of a material nobler than iron are electrically connected to each other at one or more points, and at least one portion of the part other than the conduction point is opposed to each other in the cooling water flow, Furthermore, a magnetic field is formed near a point where the cooling water flows into the iron ion supply device, and the cooling water flowing into the iron ion supply device is magnetized to promote elution of iron ions.

[Effect]

With the above configuration, iron and a material more noble than iron form a battery to ensure the elution of iron ions, and furthermore, the cooling water is distributed in a magnetized state as an electrolyte in the battery. Therefore, the elution of iron ions is further promoted.

〔Example〕

Next, one embodiment of the method of the present invention will be described with reference to FIG.

The heat exchanger 3 is equipped with a cooling pipe 6 made of a copper-based alloy, and seawater (arrow 7) is supplied as cooling water.

The above seawater 7 (cooling water) flows from the heat exchanger inlet side cooling water pipe 1 into the inlet side water chamber 2 of the heat exchanger 3 and flows through the copper-based cooling pipe 6, during which the heat exchanger is operated. In the system where the water reaches the outlet side water chamber 4 and is then drained out of the system through the piping 5, a part of the seawater is sucked up by the seawater intake pump 8 from the middle of the inlet side cooling seawater inlet piping 1 and Ion implanter 1
I am guided by 1. At the entrance of this iron ion implantation device 11, a magnetization device 1 consisting of a permanent magnet or an electric magnet is provided.
The seawater is magnetized while passing through this interior, and flows into the iron ion implantation device 11 as magnetized water. Inside the iron ion supply device 11, plates 16 made of iron and plates 15 made of a material having a nobler natural potential than iron, such as steel plates 15, are arranged alternately.
One of these abnormal materials is electrically conductive, so when seawater cooling water with electrical conductivity passes through the gap between these plates, the opposing plates form an electrically closed circuit with the cooling water. However, since both of these materials have a potential, the iron plate 16, which has a low natural potential, serves as a sacrificial electrode and is rapidly eluted to become iron ions. Incidentally, a distribution plate 17 made of a perforated plate is installed at the entrance of a plurality of passages constituted by these plates.
are provided to ensure that seawater flows evenly into each passage.

Further, if a magnetization device 10 is arranged at the entrance of the iron ion implantation device 11 to magnetize the cooling seawater and then guide it into the iron ion implantation device, the dissolution rate of iron is significantly accelerated. As a result of the inventor's experiments regarding this example, by forming a magnetic field at the cooling water inlet,
Compared to the case where you do not feel the magnetic field (only geomagnetism),
It was confirmed that the dissolution rate of iron ions was increased several tens of times. Therefore, by providing the magnetization device 10, it is possible to downsize the iron ion implantation device 11.

When iron ions are eluted into the seawater used as cooling water as described above, an iron-based protective film having corrosion resistance against seawater is formed inside the cooling pipe 6, and exhibits a remarkable anticorrosion effect.

Furthermore, this method does not require an external power source for electrolyzing iron, so it is economically inexpensive, easy to maintain, and safe (there is no risk of electric shock).

〔Effect of the invention〕

As detailed above, according to the method of the present invention,
In order to generate iron ions, there is no need for an expensive external power source, and the potential difference between different materials with different natural potentials,
By using cooling water magnetized by a magnetic field, iron ions can be supplied with high efficiency and at low cost, and it has the excellent practical effect of forming an iron-based protective film on the copper-based cooling pipes of heat exchangers. play.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of one embodiment of the method of the present invention. FIGS. 2 and 3 are explanatory diagrams of a corrosion prevention method according to the prior art. 1... Cooling seawater inlet pipe, 2... Cooling water inlet side water chamber, 3... Heat exchanger, 4... Cooling water outlet side water chamber,
5... Cooling seawater outlet piping, 6... Copper cooling pipe, 7
...Seawater as cooling water, 8...Pump, 10...
... Magnetizer, 11... Iron ion implanter, 13...
...Filter, 15...Copper plate, 16...Iron plate, 17...Distribution plate.

Claims (1)

[Claims] 1 In order to prevent corrosion of the steel alloy cooling pipes installed in the heat exchanger, in a method of supplying iron ions into the cooling water, an iron ion supply device using the natural solution method is installed in the cooling water flow path. At the same time, a member made of iron and a member made of a material more noble than iron are charged into the iron ion supply device, and the elution of iron ions from the iron member is promoted by the material nobler than iron. , and the iron member and the member made of a material nobler than iron are electrically connected to each other at one or more points, and at least one part of the part other than the point of conduction is in the cooling water flow. A magnetic field is formed near a location where the cooling water flows into the iron ion supply device, and magnetizes the cooling water flowing into the ion supply device to promote elution of iron ions. Corrosion prevention method for heat exchangers.