JP2001133195A - Method for preventing electrolytic corrosion of heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing the electrolytic corrosion of a heat exchanger capable of prolonging the durability of the exchanger and repairing the exchanger which cannot be used due to corrosion of its end plate. SOLUTION: In the heat exchanger P in which ends of a metal cooling tubes 1 of an aligned state are coupled by an end plate 2 made of a metal different from the material of the tube 1, the contact surface of the tube 1 with the plate 2 is coated with aliphatic polyamic anticorrosives 3. As the exchanger P, a shell and tube type heat exchanger P using sea water as a cooling water is used. The surface of the plate 2 coupled with the tube 1 is coated with the anticorrosives 3 by blowing or coating. As the exchanger P, a heat exchanger P in which an electrolytic corrosion has proceeded is used. The surface and the electrolytic corrosion part of the plate 2 are coated with the anticorrosives 3 by blowing or coating to impregnate the corrosion part with the anticorrosives 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing electrolytic corrosion of a shell and tube type heat exchanger using, for example, seawater, which prevents the electrolytic corrosion of a contact portion between different kinds of metal materials.

[0002]

2. Description of the Related Art Conventionally, a shell and tube type heat exchanger in which a plurality of cooling tubes are fixed by baffle plates has been used (see Japanese Patent Application Laid-Open No. 8-35790). In this heat exchanger, a cooling chamber is provided by surrounding a plurality of cooling pipes in a parallel state with a body plate, and cooling water is passed through the cooling pipe to cool oil, Freon, etc. sent to the refrigerant quality. Used as a heat exchanger.

[0003]

However, when seawater is used as the cooling water, it is known that the electric corrosion of the end plate connecting the ends of the cooling pipe becomes severe. That is, copper or a copper alloy is generally used for the cooling pipe, and a steel plate is used for a head plate for connecting the copper and the copper alloy. Therefore, an electrolytic corrosion action occurs due to a potential difference at a joint surface between the cooling pipe and the head plate. Further, when seawater is used as the cooling water, corrosion due to the electrolytic corrosion action is further intensified, and thus the corrosion of the joint between the end plate that separates the refrigerant chamber and the cooling pipe progresses fastest. For this reason, in the shell-and-tube heat exchanger, the life of the head plate is the life of the heat exchanger. In other words, extending the durability of the head plate leads to extending the durability of the shell and tube heat exchanger. Moreover, if it is possible to prevent corrosion in progress and to fill gaps and cracks caused by the corrosion with a filler, it becomes possible to repair a heat exchanger whose end plate has been damaged and cannot be used.

Accordingly, the present invention has been made to solve the above-mentioned problems, and it is possible to extend the durability of a heat exchanger, and to repair a heat exchanger whose head plate has become unusable due to corrosion. Another object of the present invention is to provide a method for preventing electric corrosion of a heat exchanger.

[0005]

In order to solve the above-mentioned problems, a first means of the present invention is to provide a metal cooling pipe 1 in a parallel state.
Of the cooling pipe 1 and a metal end plate 2 different from the material of the cooling pipe 1
In the heat exchanger P connected by the above method, an aliphatic polyamine-based anticorrosive agent 3 is coated on the contact surface between the cooling pipe 1 and the end plate 2.

The heat exchanger P of the second means is a shell and tube type heat exchanger using seawater as cooling water, and sprays the anticorrosive agent 3 on the surface of the end plate 2 to which the cooling pipe 1 is connected. Alternatively, there is a method of coating and coating the anticorrosive agent 3.

Further, the heat exchanger P of the third means is a heat exchanger P in which electric corrosion has progressed, and the anticorrosive agent 3 is sprayed or applied to the surface and the corroded portion of the end plate 2 to thereby form the corroded portion. Impregnating the anticorrosive agent 3 with the anticorrosive agent is a means for solving the problem.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as an embodiment of the present invention, a shell and tube type heat exchanger P for cooling condensed Freon of a refrigerator will be described as an example.

Reference numeral 1 shown in the figure denotes a plurality of cooling pipes arranged in parallel, and both ends of the cooling pipe 1 are connected to end plates 2, and the end plates 2 are connected to the open end of the cooling pipe 1 and the cooling pipe. The side surface 1 is separated from the refrigerant chamber P1 provided on the alligator (see FIG. 1). A shell 4 surrounds a side surface of the cooling pipe 1, and a refrigerant supply port 5 and a refrigerant discharge port 6 are provided on the side surface of the shell 4. Further, inside the shell 4, a baffle plate 7 is arranged to fix each cooling pipe 1 (see FIG. 2). Reference numeral 8 denotes a water inlet for supplying seawater, and reference numeral 9 denotes a drain outlet. Generally, copper or a copper alloy is used as a material of the cooling pipe 1. On the other hand, a steel material is used as the material of the end plate 2. Although the illustrated example shows the shell-and-tube type heat exchanger P, it goes without saying that the present invention can be applied to other types of heat exchangers P.

[0010] The electrolytic corrosion effect generated in the cooling pipe 1 is mainly the largest from the end plate 2 connecting the ends of the cooling pipe 1 to the contact portion with the cooling pipe 1 and the contact portion to the surface of the end plate 2. Become. Then, the cooling pipe 1 is connected to the contact surface between the cooling pipe 1 and the end plate 2 and the surface of the end plate 2 after coating an aliphatic polyamine-based anticorrosive agent 3 in advance. in this case,
In the heat exchanger assembling process, the electrolytic corrosion prevention method is performed. As a method of coating the anticorrosive agent 3, an arbitrary means is selected from a means for dipping the end plate 2 in a solution of the anticorrosive agent 3, a spraying means, a brush applying means, and the like.

The heat exchanger P after assembly is coated with the anticorrosion agent 3 by spraying or applying the anticorrosion agent 3 onto the surface of the end plate 2.

The corrosion inhibitor 3 is sprayed or applied to the surface and the corroded portion of the end plate 2 to impregnate the corroded portion with the corrosive agent 3 on the heat exchanger P which has already been corroded by the electrolytic corrosion. Things.

The aliphatic polyamine used for the corrosion inhibitor 3 is
A two-part epoxy resin that uses an aliphatic polyamine as a curing agent. The thermal expansion coefficient of this resin is
It is 5.0 × 10-5 / ° C and has excellent corrosion resistance and penetrability, so it can penetrate even small cracks. The aliphatic polyamine is also effective as a filler because it hardens in the gap due to cracks and corrosion after infiltration.

The heat exchanger P may be a heat exchanger P used for an oil cooler or an air cooler other than the illustrated example. In particular, in this air cooler, when atmospheric moisture liquefies as condensed water, if oxides such as sulfurous acid gas in the atmosphere are dissolved in the condensed water, the drain is acidified and electric corrosion occurs.
The electrolytic corrosion prevention method of the present invention can also prevent this kind of electrolytic corrosion.

[0015]

According to the present invention, the method for preventing electrolytic corrosion described above
The original objective has been achieved. That is, by the method of coating the contact surface between the cooling pipe 1 and the end plate 2 with the aliphatic polyamine-based anticorrosive agent 3, it is possible to prevent the electrolytic corrosion action between dissimilar metals. Therefore, in all the heat exchangers P, corrosion due to the electrolytic corrosion action of the junction between dissimilar metals is prevented.

Moreover, in a shell and tube heat exchanger using seawater as cooling water, the surface of the end plate 2 to which the cooling pipe 1 is connected is sprayed or applied with the anticorrosion agent 3 to coat the anticorrosion agent 3. It is possible to prevent the electrolytic corrosion of a portion where corrosion is severe due to dissimilar metals and seawater. As a result, the durability of the head plate 2 can be increased, and the useful life of the shell-and-tube heat exchanger P can be extended over a long period of time.

Further, in the heat exchanger P in which the electrolytic corrosion has progressed, the surface of the head plate 2 and the corroded portion are sprayed or applied with the anticorrosive agent 3 to impregnate the corroded portion with the anticorrosive agent 3, whereby the corrosive plate is corroded. It is now possible to repair heat exchangers that can no longer be used. As a result, the end plate 2 is damaged and cannot be used, and the heat exchanger P
Can be repaired and reused.

Since the aliphatic polyamine is used as the anticorrosive agent 3, it has permeability, so that it can penetrate even a slight crack. Further, the aliphatic polyamine hardens in gaps due to cracks and corrosion after infiltration, and thus effectively functions as a filler. In addition, as a means for applying the aliphatic polyamine-based anticorrosive agent 3, a spraying means by a spray, a coating means by brushing, and the like can be selected, so that the coating operation can be performed very easily.

As described above, according to the present invention, it is possible to extend the durability of the heat exchanger, and it is possible to repair the heat exchanger which has become unusable due to corrosion of the head plate. It produces various effects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an embodiment of a heat exchanger that performs an electrolytic corrosion prevention method of the present invention.

FIG. 2 is a sectional view of the heat exchanger shown in FIG.

[Explanation of symbols]

 P Heat exchanger P1 Refrigerant chamber 1 Cooling pipe 2 End plate 3 Corrosion inhibitor 4 Shell 5 Refrigerant supply port 6 Refrigerant discharge port 7 Baffle plate 8 Water supply port 9 Drain port

Claims (3)

[Claims] 1. A heat exchanger in which ends of metal cooling pipes in a parallel state are connected to each other by a metal end plate different from the material of the cooling pipes. A method for preventing electrical corrosion of a heat exchanger, comprising coating a corrosion inhibitor of the type described above. 2. The heat exchanger is a shell-and-tube type heat exchanger using seawater as cooling water, and the anticorrosive is sprayed or applied to a surface of a head plate connected to a cooling pipe to coat the anticorrosive. The method for preventing electrolytic corrosion of a heat exchanger according to claim 1. 3. The heat exchanger according to claim 1, wherein the corrosive agent is sprayed or applied to a surface and a corroded portion of the head plate to impregnate the corroded portion with the corrosive agent. 3. The method for preventing electrolytic corrosion of a heat exchanger according to 1 or 2.