JPS636395A - Repair method for multitube type fluororesin-made heat exchanger - Google Patents

Abstract

PURPOSE:To be able to repair a damaged heat exchanger simply without a bad influence on adjoining tubes by a method wherein in the openings of tubes, adjoining to a fluororesin-made tube, where a damage takes place, heat-resisting pins which even on heated are not welded to fluororesin constituting the tubes are inserted, under which condition the opening of the damaged tube is clogged by hot-meltable fluororesin. CONSTITUTION:In the openings of fluororesin-made tubes 2a, 2b, 2c,... adjoining to a damaged fluororesin-made tube 1, heat-resisting pins 3a, 3b, 3c,... which are not welded to the fluororesin constituting tubes at the heating time are inserted. A welding rod 6 made of hot-meltable fluororesin is inserted into the damaged tube 1 and the hot air from a hot air gun is sprayed to the opening of the damaged tube 1 and the welding rod 6 is melted to unify the peripheral surface of the rod 6 and the inner circumferential surface of the damaged tube 1. After the damaged tube 1 is clogged, the pins 3a, 3b, 3c,... are removed from the adjoining tubes 2a, 2b....

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for repairing a multi-tubular fluorine resin heat exchanger, and more specifically to a method for repairing a multi-tubular fluorine resin heat exchanger. Concerning how to repair the dexterity tube if it is partially damaged.

2. Technical Background and Problems Conventionally, shell-and-tube heat exchangers made of metals such as stainless steel, nickel, and copper have been widely used as heat exchangers. Although such metal heat exchangers have high thermal conductivity and overall heat transfer coefficient, they have problems such as insufficient corrosion resistance against acid solutions and the tendency for scale to adhere to the surface. Ta.

For this reason, multi-tubular heat exchangers made of fluororesin have been developed. This fluororesin heat exchanger has a structure in which 40 to 2,500 fluororesin tubes are bundled and integrated into a honeycomb shape by heat fusion at both ends, and has excellent heat resistance and chemical resistance. It also has the advantage of having a smooth surface that prevents scale from adhering to it.

However, fluororesin has a lower thermal conductivity than various metals, so in order to improve its performance as a heat exchanger, the wall thickness of the fluororesin duplex is made as thin as possible without causing any practical problems. In this way, fluororesin tubes are thin, and superheated steam is often supplied into the fluororesin tubes during heat exchange, so the superheated steam causes the fluororesin tubes to move and become adjacent to each other. The tubes may rub against each other, which may cause the walls of the fluororesin tubes to wear out, or static electricity may be generated where the rubbing stakes meet, resulting in pinholes in the fluororesin tubes. Ta.

If a pinhole occurs in the fluororesin tube,
Not only did this impair its performance as a heat exchanger, but it also frequently caused major failures such as corrosive fluid flowing back into the equipment.

Therefore, if damage such as a pinhole occurs in the fluororesin tube constituting the fluororesin heat exchanger, it is necessary to repair the damage.

Conventionally, nerve repair of damaged fluororesin tubes has been carried out as follows. That is, if a fluororesin tube is damaged, the entire tube is closed by closing the open end of the damaged tube at the tube convergence end. To close the open end of a damaged tube with the tube converging end, generally, a welding rod made of heat-melting fluororesin is inserted into the open end to block hot air generated from a hot air gun into the open end. This is done by melting the hot-fusible fluororesin by spraying it on the end and heating it, and fusing the open end wall of the damaged tube and the hot-fusible fluororesin welding rod together to integrate them. It's been coming.

However, when attempting to close the open end of the damaged fluororesin tube as described above, the open end of the damaged fluororesin tube may be closed, but at the time of this closure, the converging end of the tube is considerably damaged. As a result, the fluororesin tubes adjacent to the damaged fluororesin tube are also exposed to considerable high temperatures and are thermally deformed, causing damage between the damaged fluororesin tube and the adjacent tube. A serious problem occurred in that peeling occurred. These problems were particularly serious when the tube was made of polytetrafluoroethylene. - On the other hand, if the fluororesin tube is made of a heat-melting fluororesin such as a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (hereinafter sometimes abbreviated as PFA), the above problems may occur. In addition, there has been a problem in that adjacent fluororesin tubes are fused together due to deformation due to heating.

If separation occurs between adjacent fluororesin tubes, the heat exchange fluid will leak to the outside through the gap between the tubes, which is a fatal defect for the heat exchanger. .

Purpose of the Invention The present invention aims to solve all of the problems associated with the above-mentioned prior art at once. It is an object of the present invention to provide a method for repairing a multi-tubular fluororesin heat exchanger, which allows the damage to be easily repaired without adversely affecting adjacent duplexes.

Summary of the Invention The present invention provides a method for repairing a multi-tube fluororesin heat exchanger in which the bundled end portions of a large number of fluororesin tubes are integrated. With a heat-resistant pin inserted into the opening of the fluororesin tube that does not fuse with the fluororesin that makes up the tube even when heated, remove the opening of the fluororesin tube where the damage occurred at the tube convergence end. It is characterized by being closed with a thermofusible fluororesin melted by heating.

According to the method for repairing a multi-tubular fluororesin heat exchanger according to the present invention, a heat-resistant pin is inserted into the opening of the fluororesin tube adjacent to the damaged tube, The opening of the tube is closed with heat-melting fluororesin, which prevents the tube from deforming due to heating when the opening of a damaged tube is closed.
This prevents the damaged tube from separating from the adjacent tube, or from fusion of the tubes to each other, and furthermore, the heat-melting fluororesin is firmly integrated into the inner circumferential surface of the damaged tube. can be converted into

DETAILED DESCRIPTION OF THE INVENTION A method for repairing a multi-tubular fluororesin heat exchanger according to the present invention will be described below with reference to the drawings.

In the present invention, a damaged multi-tubular fluororesin heat exchanger is repaired.
It consists of a large number of fluororesin tubes ranging from 40 to 2,500, and the converging ends of these tubes are generally integrated into a honeycomb shape.

The fluororesin constituting such a tube may or may not be heat-meltable.
Polytetrafluoroethylene (PTFE) is used as a non-heat-melting fluororesin, and as a fluororesin that is a heat-melting fluororesin, the above-mentioned PFA and a copolymer of tetrafluoroethylene and hexafluoropropylene are used. FEP, EPE which is a copolymer of tetrafluoroethylene, hexafluoropropylene and perfluoroalkyl vinyl ether, PCTFE which is polychlorotrifluoroethylene, ETFE which is a copolymer of ethylene and tetrafluoroethylene, etc. It will be done.

By the way, a repair method when one of the fluororesin tubes constituting the multi-tube fluororesin heat exchanger as described above is damaged will be explained. First, as shown in FIGS. 1 and 2, fluororesin tubes 2a, 2b, 2C, etc. adjacent to the damaged fluororesin tube 1...
Heat-resistant pins 3a, 3b, 3C, . . . that do not fuse with the fluororesin constituting the tube even when heated are inserted. As described above, a pin that does not fuse with the fluororesin is used, and specifically, it is preferable to use a pin made of metal or ceramics.

The pin 3 is preferably configured to have a bulge 4 at the top and a leg 5 at the bottom of the bulge 4, and when the pin 3 is inserted into the tube 2a... At this time, the bulging portion 4 prevents the pin 3 from penetrating deeply into the tube 2a.

When the pins 3a, 3b, etc. as described above are inserted into the fluororesin tubes 2a, 2b, etc. adjacent to the fluororesin tube 1, which has been damaged in this way, the breakage occurs at the tube converging end. The opening of the fluororesin tube 1 where this has occurred is closed with heat-melting fluororesin melted by heating.

In order to close the opening of the damaged fluororesin tube 1 with a heat-melting fluororesin melted by heating, specifically, the damaged fluororesin tube 1 is filled with a heat-melt fluororesin. In this state, hot air from a hot air gun is blown into the opening of the damaged fluororesin tube 1 to melt the heat-fusible fluororesin welding rod 6, and this welding is carried out. The outer peripheral surface of the rod 6 and the inner peripheral surface of the damaged fluororesin tube 1 may be integrated. Alternatively, the opening of the fluororesin tube 1 where the damage has occurred can be done by pouring heated and melted heat-melting fluororesin into the opening of the fluororesin tube 1 where the damage has occurred while heating the opening. The section may be closed.

When closing the opening of the damaged fluororesin tube 1, the above-mentioned pins 3a,
3b is inserted, even if the wall surface of tube 1, which was damaged during heating, attempts to expand outward due to thermal expansion, the wall surfaces of adjacent tubes 2a, 2b, etc. will not deform, so damage will occur. No separation occurs between the tube 1 and the adjacent tubes 2a, 2b. Moreover, the tube 2a adjacent to the damaged tube 1,
2b... have pins 3a, 3b... inserted therein, and these adjacent tubes 2a, 2b...
does not deform when heated, the inner circumferential surface of the damaged tube 1 and the outer circumferential surface of the thermofusible fluororesin melted by heating are crimped and firmly integrated.

After closing the damaged tube 1 as described above, the pins 3a, 3 are removed from the adjacent duplexes 2a, 2b...
If b... is removed, the repair of the multi-tubular fluororesin heat exchanger is completed.

Effects of the Invention According to the method for repairing a multi-tube fluororesin heat exchanger according to the present invention, a heat-resistant pin is inserted into the opening of the fluororesin tube adjacent to the damaged tube, and the damaged tube is repaired. Since the opening of the tube where the damage occurred is closed with heat-melting fluororesin, the tube is prevented from deforming due to heating when the opening of the tube where the damage occurred is closed.
This prevents the damaged tube from peeling off from the adjacent tube, or the duplexes from fusion bonding to each other.Furthermore, heat-melting fluororesin is not applied to the inner circumferential surface of the damaged tube to be repaired. It can be strongly integrated and provides a reliable repair method.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams of a method for repairing a multi-tubular fluororesin heat exchanger according to the present invention. 1...Tube with damage

Claims (1)

[Claims] 1) Insert a heat-resistant pin that will not fuse with the fluororesin that makes up the tube even when heated into the opening of the fluororesin tube adjacent to the damaged fluororesin tube, and remove the tube converging end. , the opening of the damaged fluororesin tube is closed with a heat-melting fluororesin melted by heating,
A method for repairing a multi-tube fluororesin heat exchanger in which the condensed end portions of a large number of fluororesin tubes are integrated.