JPS6325496A - Heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the corrosion of a part in gas near the gas and liquid interface of the outer peripheral surface of a heat transfer tube and permit the holding of high reliability for a long period of time, by a method wherein the gas and liquid interface of the outer peripheral surface of the heat transfer tube is coated with a corrosion-resistant material. CONSTITUTION:The upper part of the lowest part of a gas and liquid interface 2, positioned above a dispersion plate 6 on the outer peripheral surface of a traditional heat transfer tube 1 for a heat exchanger, is coated with the heat- shrinkable tubing of the polymer of 4-ethylene fluoride. According to this method, the heat transfer tube is hardly corroded and is provided with high reliability whereby the heat exchanger with a long life may be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat exchanger used in an absorption heat pump or the like.

[Conventional technology]

Conventionally, as this type of heat exchanger, for example, Japanese Patent Application Laid-Open No. 61-4
There was one shown in Publication No. 4261. To explain this with reference to the figure, in the figure, 1 is the heat exchanger tube, 2 is the gas-liquid interface on the surface of the heat exchanger tube 1, and it changes depending on the flow of the PII liquid.

3a and 3b are upper and lower tube plates, on which one or more heat exchanger tubes 1 are fixed. 4 is an absorption liquid inlet provided at the top of the body 1) provided between the upper and lower tube plates 3a and 3b.
). 5a1. tilfl
Thick absorption liquid, 5bl:j The thick absorption liquid 5a flows down, absorbs water vapor, and becomes diluted. 6 is a dispersion plate, and there is a gap between the dispersion plate 6 and the heat transfer tubes 1 loosely inserted, and the absorption liquid 5a is distributed to each heating tube 1 and flows down. 7. A water vapor inlet provided in the lower part of the dispersion plate 6 of the body 1);
Reference numeral 8 denotes an outlet for the absorption liquid provided at the lower part of the body 1), through which the solution that has become diluted by absorbing water vapor is sent out. 9 is an inlet for water provided below the lower tube plate 3b, and 10 is an outlet for water vapor generated by vaporization of water provided above the upper tube plate 3a.

Next, the operation will be explained. The concentrated absorbing liquid 5a sent from the absorbing liquid port 4 accumulates on the dispersion plate 6 in the shell 1) and flows down the surface of the heat exchanger tube 1 at a constant flow rate. Absorption liquid 5
An inhibitor is added to a to prevent corrosion of the constituent materials that come into contact with the inhibitor. Then, the water vapor sent from the steam lower part is absorbed into the lower part of the dispersion plate 6 in the shell 1), and the absorbed liquid 5b becomes diluted.The absorbed liquid 5b is discharged from the absorption liquid outlet 8 and sent to a generator (not shown). It is shrunk and circulated. The heat generated during the absorption of water vapor exchanges heat with the water fed through the water inlet 9, and the water is turned into steam and supplied to the chemical process through the outlet 10.

[Problem that the invention seeks to solve]

The conventional heat exchanger is constructed as described above, and since the heat exchanger tube 1 is made of copper, droplets of absorption liquid adhere to the outer peripheral surface of the heat exchanger tube in the gas phase near the gas-liquid interface 2. There was a problem in that the inhibitor in the absorption liquid was not effective in some areas, making them susceptible to corrosion.

This invention was made to solve the above-mentioned problems, and provides a heat exchanger that has high reliability over a long period of time by preventing corrosion in the air region near the gas-liquid interface on the outer peripheral surface of the heat exchanger tube. The aim is to provide this at a low cost and with almost no deterioration in heat exchange characteristics.

[Means for solving problems]

The present invention provides a heat exchanger as described above, in which the gas-liquid interface on the outer peripheral surface of the heat transfer tube is coated with a corrosion-resistant material.

[For production]

In the heat exchanger according to the invention of B, the portion of the heat transfer tube located on the distribution plate is a portion that does not participate in heat transfer, so even if it is coated with a corrosion-resistant material, the heat exchange characteristics will not be deteriorated. In addition, the gas phase near the gas-liquid interface on the outer circumferential surface of the heat transfer tube is prone to corrosion, but corrosion in this area can be prevented by coating the gas-liquid interface with a corrosion-resistant material, and the length of the portion covered with the corrosion-resistant material Since the length is short, the amount of corrosion-resistant material required for coating is small, the material cost is low, and the coating process is easy.

〔Example〕

An embodiment of the present invention will be described below.

In Example B, the lowest part and above of the gas-liquid interface 2 located on the dispersion plate 6 on the outer peripheral surface of the heat exchanger tube 1 of the conventional heat exchanger shown in the figure is covered with a heat-shrinkable tube made of tetrafluoroethylene polymer. . Note that the configuration of this embodiment other than those described above is the same as that of the conventional heat exchanger shown in the drawings.

In order to confirm the effect of Example B, a corrosion test was conducted using a test piece having a gas-liquid interface. The test piece used was a deoxidized steel tube (diameter: 10 mm, length: 40 mm, wall thickness: 1 mm), and half of one side of the tube was covered with a heat-shrinkable tube made of tetrafluoroethylene polymer. The test solution was a 54% aqueous solution of lysium bromide,
0.2% lithium hydroxide as inhibitor, 0.01
5% lithium molybdate and 0.14% benzotriazole (BTA) are added. The test piece is placed against a container made of tetrafluoroethylene polymer with the side covered with the heat shrink tube facing up, and the test liquid is poured into the container until the uncovered part is submerged in the liquid. The entire container was placed in a sealed container and sealed with IQOwl air for testing.

The test was conducted in a constant temperature bath at 160° C. for two weeks, and the corrosion status of the test piece was investigated. As shown in the experimental example in the table below, the results show that there is no local corrosion and the amount of corrosion is 1. t, g
This is a value that does not pose any practical problem. For comparison, the same table also shows the results of an experiment conducted under the same conditions as above on a copper specimen without the tube covered. From the same table, it can be seen that deep corrosion occurred on the surface of the specimen in the air, and the amount of corrosion was more than 10 times that of the examples of the present invention.

Further, in the above embodiment, the coating portion on the outer circumferential surface of the heat exchanger tube is only the upper portion of the distribution plate that does not participate in heat transfer, and does not affect the heat exchange characteristics of the heat exchanger. Furthermore, in this example, a heat-shrinkable tube of tetrafluoroethylene copolymer was used as the covering material, so the covering operation was simple and the material had excellent heat resistance and chemical resistance.

In the above embodiment, the anti-corrosion coating was provided only on the upper part of the dispersion plate 6 on the outer circumferential surface of the heat exchanger tube 1.
15a and the gas-liquid interface with the dilute solution 5b, and the heat exchanger tube 1
Since a similar phenomenon is thought to occur at the gas-liquid interface with the PIIi solution 5b on the outer peripheral surface, it is advisable to provide an anti-corrosion coating made of a corrosion-resistant material to these areas as well.

Further, in the above embodiment, the case of an absorber of an absorption heat pump was explained, but the present invention can also be applied to a generator of an absorption heat pump, an absorber of an absorption refrigerator, and a heat exchanger tube of the generator. These also produce the same effects as the above embodiments.

〔Effect of the invention〕

As described above, according to the present invention, the gas-liquid interface on the outer peripheral surface of the heat exchanger tube in contact with the absorption liquid is coated with a corrosion-resistant material, so the heat exchanger tube does not corrode, has high reliability, and has a long service life. In addition, it is easy to construct, requires less coating material, provides a highly reliable heat exchanger at low cost, and has the effect of hardly deteriorating heat exchange characteristics. .

[Brief explanation of the drawing]

The figure is a cross-sectional side view showing an absorber of a conventional absorption heat pump. 1. Heat exchanger tube, 5a... Absorption liquid, 6. Dispersion plate, 1).
・Torso. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa (2 others) □ 21゜ノ5b / :(i main 6!4N next Z・)F-WeiλAr:)

Claims (2)

[Claims] (1) A heat exchanger having a dispersion plate and dispersing a solution and causing it to flow over the surface of a heat exchanger tube for heat exchange, characterized in that the gas-liquid interface on the outer peripheral surface of the heat exchanger tube is coated with a corrosion-resistant material. Heat exchanger. (2) The heat exchanger according to claim 1, wherein the corrosion-resistant material is a heat-shrinkable tube made of tetrafluoroethylene polymer.