JPS5844199B2 - Multi-tube heat exchanger that can be blind plugged by welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-tubular heat exchanger that can be easily repaired, and more particularly to a heat exchanger having a structure that allows reliable and reliable blind plugging by welding. .

A shell-and-tube heat exchanger has a large number of heat exchanger tubes and a tube sheet to which both ends of the heat exchanger tubes are attached, and an inner area of the heat exchanger tubes and an outer area of the heat exchanger tubes are separated, and a fluid with a temperature difference is allowed to flow between these areas. Equipment that exchanges heat, such as steam generators in nuclear power plants and high-temperature, high-pressure heat exchangers in chemical plants, are made of materials such as low-alloy steel to prevent stress corrosion. , This type of material requires preheating and post-heat treatment during welding.

At the time of manufacturing the heat exchanger, each assembly block or the entire assembly block can be heat treated under the same conditions according to the manufacturing process, so there is no problem with assembly by welding.

However, if several of the heat exchanger tubes are damaged after they have been manufactured, it is necessary to replace the damaged heat exchanger tubes with new ones, or insert blind plugs at both ends of the tube plate where the heat exchanger tubes are attached. The inside of the heat exchanger tube must be separated from the outside of the heat exchanger tube for repair, but this case poses a problem.

As mentioned above, if the heat exchanger is made of low-alloy steel, etc., preheating and post-heat treatment are required when blind plug welding is performed at the end of the heat exchanger tube. It must be applied either entirely or locally to the repaired area only.

However, heat-treating the whole part again after repair gives the material an unnecessary heat history, which leads to a decrease in strength, which is undesirable, and heat-treating locally is extremely difficult from a structural and operational standpoint. Therefore, it was thought that it would be impossible to weld blind plugs with heat exchangers made of the above-mentioned materials, because sufficient heat treatment could not be performed and reliability was poor.

In addition to welding, the blind plug can be made by explosive bonding, but the explosive bonding method has problems in terms of workability, reliability, inspection method, etc.

The present invention has been made in view of the actual state of the prior art as described above, and its purpose is to prevent the main body from being made of a material such as low-alloy steel that requires preheating and post-heat treatment during welding. Another object of the present invention is to provide a multi-tubular heat exchanger that can be reliably and reliably sealed by welding, does not require heat treatment, and is easy to repair.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a structural diagram showing an example of a shell-and-tube heat exchanger suitable for applying the present invention.

A large number of heat exchanger tubes 1 are arranged substantially in parallel, and both ends of the heat exchanger tubes 1 are each attached to a tube plate 2 by welding, so that an inner region 3 of the heat exchanger tubes and an outer region 4 of the heat exchanger tubes are isolated.

The shell 5 surrounds a large number of heat exchanger tubes 1, and both ends thereof are connected to the tube plate 2.
The heat exchanger tube outer section 4 contains fluid.

A partition cover 6 is attached to the outside of the tube plate 2 with bolts and nuts 8 through a gasket 7.

The fluid inside the heat exchanger tube enters from the inlet A, passes through the heat exchanger tube 1, and flows out from the outlet B.

On the other hand, the fluid outside the heat transfer tube enters from the inlet C, flows inside the shell 5, and flows out from the outlet.

During this time, heat exchange takes place between both fluids via the heat exchanger tube wall.

For reference, FIGS. 2 and 3 show enlarged views of the joints between conventional heat exchanger tubes and tube sheets.

As mentioned above, heat exchangers used particularly at high temperatures and high pressures are made of low-alloy steel, and the tube sheets 2 and heat exchanger tubes 1 are made of such materials as they are.

Now, in the present invention, as shown in FIGS. 4 and 5, the surface of the inner area of the heat exchanger tube of the tube sheet 2 made of low alloy steel, etc.
In other words, the surface on the side of the partition is lined with a material that does not require heat treatment during welding, such as Inconel or low carbon steel.
is applied.

Lining methods include explosion bonding and welding.

In the case of welding, the lining material is welded and then holes for the heat exchanger tubes are drilled in the tube sheet.

Therefore, in the heat exchanger of the present invention, after manufacturing is completed,
Even if some of the heat exchanger tubes 1 are damaged, the inside of the heat exchanger tubes and the outside of the heat exchanger tubes can be isolated by providing blind plugs at both ends of the tube sheet 2 where the heat exchanger tubes 1 are attached. can be easily repaired.

That is, as shown in FIGS. 6 and 7, the damaged heat exchanger tube 1
A blind plug 10 made of the same material as the lining 9 is inserted into the end of the tube sheet 2, and the periphery thereof is welded to the lining 9.

Since the lining 9 and the blind plug 10 are made of a material such as Inconel or low carbon steel that does not require heat treatment during welding, the above-mentioned repair work is extremely easy.

Since the present invention is a multi-tubular heat exchanger configured as described above, even if the main body is made of a material that requires heat treatment during welding, such as low alloy steel, the heat exchanger tubes will not break. When,
Welding allows for a reliable and reliable blind plug, and there is no need for heat treatment, making it easy to repair, and furthermore, it does not impart unnecessary thermal history to the constituent materials, so there is no risk of weakening. It can have many excellent effects, including the fact that

[Brief explanation of drawings]

FIG. 1 is a structural diagram of a typical example of a shell-and-tube heat exchanger that is the object of the present invention, FIGS. FIG. 5 is an enlarged sectional view of the vicinity of the connection between the heat exchanger tube and the tube plate of the heat exchanger according to the present invention, and FIG. 6 and FIG. 7 are explanatory diagrams showing the state of blind plug welding. 1... Heat exchanger tube, 2... Tube sheet, 3...
... Heat exchanger tube inner section, 4 ... Heat exchanger tube outer section, 5 ... Shell, 6 ... Partition chamber cover, 9
... Lining, 10 ... Blind plug.

Claims (1)

[Claims] 1 A heat exchanger tube is provided with a plurality of heat exchanger tubes with both ends attached to a tube plate and a shell surrounding them, an inner area of the heat exchanger tube and an outer area of the heat exchanger tube are defined, and a fluid with a temperature difference is distributed between these areas. In a multi-tubular heat exchanger that has a structure in which heat exchange is performed by flowing and is made of a material that requires heat treatment during welding, the surface of the inner area of the heat exchanger tube of the tube sheet is made of Inconel, low carbon steel, etc. A multi-tubular heat exchanger capable of being blind plugged by welding, characterized in that it is lined with a material that does not require heat treatment during welding, such as.