JPH037394Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is used for heat exchangers made of copper alloy used in structures that use seawater as cooling water, such as thermal power plants, ships, oil plants, etc. The present invention relates to an anticorrosion and antifouling device for preventing corrosion of members and preventing marine organisms from adhering to the structure.

[Prior Art] Structures that use seawater as cooling water have the problem of corrosion of copper alloy members (e.g. cooling pipes, tube sheets) due to seawater and staining due to adhesion of marine organisms.
To solve these problems, iron ion implantation using iron electrode electrolysis and sodium hypochlorite injection using seawater direct electrolysis have been commonly used.

However, since performing corrosion prevention and antifouling separately requires a huge amount of equipment cost, the applicant of the present application believes that it is most economical to satisfy both anticorrosion and antifouling using one electrolytic device. Focusing on this advantage, he filed an application for an invention as disclosed in Japanese Patent Publication No. 52-33582.

In other words, the gist is ``In the electrolytic current circuit between the insoluble anode and cathode for seawater electrolysis, an iron sacrificial body is provided in a state that is electrically insulated from the anode and cathode, This is an anti-corrosion and anti-fouling device characterized by simultaneously supplying chlorate and iron ions that are dissolved and produced by electrolytic corrosion caused by electrolytic current.

In addition, as another conventional technology based on the same technical idea, as shown in Japanese Patent Publication No. 19336/1983, "One or several iron plates are placed between the anode and cathode of one electrolytic cell. and a variable resistor is connected between the anode and the iron plate of the intermediate electrode and between the cathode and the iron plate of the intermediate electrode to adjust the electrolytic potential difference between them. and antifouling methods."

[Problems to be solved by the invention] The device disclosed in the above-mentioned Japanese Patent Publication No. 52-33582 cannot control the anti-corrosion and anti-fouling functions separately. If the supply of iron becomes too small, sufficient antifouling effects cannot be obtained, and conversely, if antifouling is the main focus, the supply of iron ions becomes too large, shortening the replacement cycle of the iron sacrificial body and reducing heat exchange. The drawback was that the heat transfer efficiency of the vessel was reduced, and it was not put into practical use.

On the other hand, the method disclosed in Japanese Patent Publication No. 52-19336 is
Although it is possible to control the anti-corrosion and anti-fouling functions separately, it has the drawbacks of large current loss and poor control efficiency because they are adjusted using variable resistors, and also because of the scale that forms and adheres to the cathode during electrolysis. However, due to the common electrolytic current circuit,
It is not put into practical use because it has the problem that all anti-corrosion and anti-fouling functions stop at once if a failure occurs in a part of the circuit, such as a short circuit, worn out electrodes, or an abnormality.

The purpose of this invention is to provide an anti-corrosion and anti-fouling device for heat exchangers that eliminates the above-mentioned problems of conventional devices and enables efficient control of anti-corrosion and anti-fouling functions. do.

[Means for solving the problem] In order to achieve this purpose, this invention has the following configuration.

That is, in the anti-corrosion and anti-fouling device according to this invention, half of the even number of iron electrodes are each connected to the positive electrode and the negative electrode of the anti-corrosion DC power supply via a polarity converter.

Of these, half of the iron electrodes connected to the negative electrode are commonly connected to the negative electrode of the antifouling DC power supply device.

On the other hand, an insoluble anode is connected to the positive electrode of the antifouling power supply device.

[Example] An example of this invention will be described with reference to the drawings.

FIG. 1 is a wiring diagram showing one embodiment of this invention, and FIG. 2 is a schematic plan view showing another arrangement of electrodes.

An anticorrosion/antifouling unit is inserted and installed through an opening provided at the upper part of the water intake pipe 10 of the heat exchanger.

This unit consists of a pair of rod-shaped iron electrodes 1 and 2.
Insoluble anodes 3 made of titanium or tantalum plated with platinum are insulated and fixed at regular intervals.

The iron electrode 1 is connected to the positive electrode of the anti-corrosion DC power supply 5 through the switching contact 7 of the polarity converter 4, and similarly, the iron electrode 2 is connected to the negative electrode of the anti-corrosion DC power supply 5 through the switching contact 8. Connected.

Further, the iron electrode 2 is also connected to the negative electrode of the antifouling DC power supply device 6 via a branch point 9, and the insoluble anode 3 is connected to this positive electrode.

In this example, one pair of iron electrodes was used, but the second
As shown in the figure, two or more pairs may be used as long as the number is even so that polarity can be changed, and two or more insoluble anodes may be used.

The anticorrosion and antifouling device described above is operated as follows.

Turn on the switch of the corrosion protection DC power supply 5 to form an iron electrolytic circuit in which the iron electrode 1 becomes the anode and the iron electrode 2 becomes the cathode, and about 0.03 PPM of iron ions are eluted from the iron electrode 1 to form a copper alloy member. Measure corrosion protection.

Similarly, the antifouling DC power supply device 6 is turned on to form a seawater electrolytic circuit with the insoluble anode 3 and the iron electrode 2 as counter electrodes, and about 0.2 PPM of sodium hypochlorite is generated at the anode, and the seawater system is Prevents marine organisms from adhering to the inner surface.

After 6 to 12 hours have elapsed, the polarity of the iron electrodes is changed by the polarity converter 4, so that iron ions are eluted from the iron electrode 2.

At this time, the iron electrode 1 becomes the opposite electrode of the insoluble anode 3.

Thereafter, similar polarity conversion is repeated.

Adjustment of the output current amount in the device of this invention is as follows:
This is done using a thyristor built into each power supply.

In this way, in this design, the cathode always serves as a common counter electrode for anticorrosion and antifouling, so a larger amount of scale is deposited on the cathode than in the past, but due to polarity conversion, the iron electrode is being converted to an anode. Moreover, scale attached to the cathode can be removed extremely easily at the same time as the iron ions are eluted.

[Effects of the invention] This invention has the following excellent effects.

A: The anti-corrosion and anti-fouling electrolytic circuits are constructed as separate circuits, so even if a malfunction occurs in one part of the circuit, such as a short circuit, worn out electrodes, or an abnormality, the anti-corrosion and anti-fouling functions will be maintained at once. Never stop.

B. Previously, variable resistors were used to control the anti-corrosion and anti-fouling functions, resulting in extremely poor control efficiency, but with this invention, direct control is possible without loss of current. Control efficiency is extremely high.

C By polarity conversion, the scale attached to the cathode during electrolysis is removed, so the electrolytic efficiency in anticorrosion and antifouling is improved and made uniform, and the ratio of iron electrodes becoming anodes is reduced to half. , the lifespan of iron electrodes is doubled compared to conventional ones.

[Brief explanation of the drawing]

FIG. 1: A wiring diagram showing one embodiment of this invention. FIG. 2: A schematic plan view showing the electrode arrangement of this invention. DESCRIPTION OF SYMBOLS 1... Iron electrode, 2... Iron electrode, 3... Insoluble anode, 4... Polarity converter, 5... Corrosion protection DC power supply device, 6... Antifouling DC power supply device.

Claims (1)

[Scope of utility model registration request] Half of the even number of iron electrodes 1 and 2 are connected to the positive and negative electrodes of the anticorrosion DC power supply 5 via a polarity converter 4, and the insoluble anode 3 is connected to the positive electrode of the antifouling DC power supply 6. An anticorrosive and antifouling device for heat exchangers, characterized in that half of the iron electrodes 1 and 2 are alternately connected to the negative electrode of the power supply device 6 via the polarity converter 4.