JPH0625339B2 - Absorption liquid for absorption refrigerator - Google Patents

Description

TECHNICAL FIELD The present invention relates to an absorption refrigerating machine which uses an aqueous solution containing a highly corrosive lithium halide as an absorbing solution, and the absorbing solution contains an additive having a large corrosion inhibiting performance. The present invention relates to an absorption liquid for an absorption refrigerator, which suppresses corrosion of the metal material of the absorption refrigerator.

[Conventional technology]

Conventionally, an absorption refrigerator has generally used an aqueous solution of lithium halide, particularly an aqueous solution of lithium bromide, as an absorbing liquid. However, it is well known that an aqueous lithium bromide solution has a corrosive property with respect to metallic materials such as mild steel, copper and brass. In order to use these metals as a material for an absorption refrigerator, when an aqueous solution of lithium bromide is used as an absorption liquid, it is essential to add an inhibitor to prevent corrosion. Conventionally, many commonly used inhibitors include, for example:
There are chromate, molybdate, tungstate, nitrate, nitrite, azoles, amines and the like. Most of these are oxidants, which suppress corrosion by forming a dense protective film on the steel surface.

[Problems to be Solved by the Invention]

However, it is difficult to avoid the generation of hydrogen gas in the reaction during the film formation as described above, and this hydrogen gas causes a pressure increase in the refrigerator, which often causes trouble in operation. There is a point. In addition to this, in recent years, there has been a demand for higher efficiency and air cooling of absorption refrigerators.
Increasing the concentration of the absorbing liquid and increasing the temperature inside the refrigerator have come to be carried out. Along with this, there is a problem that it is difficult to use an organic inhibitor, nitric acid, or a nitrite inhibitor, which is problematic in decomposition at high temperature. Further, in general, the aqueous solution of lithium halide has a higher temperature and a higher concentration,
Since the corrosiveness becomes strong, there is a problem that it is difficult to sufficiently suppress the corrosion with the inhibitor.

An object of the present invention is to provide an absorption liquid for an absorption refrigerator, which uses an aqueous solution containing lithium halide as an absorption liquid, and which suppresses corrosion of a metal material used in the absorption refrigerator.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention provides an absorption liquid for an absorption refrigerating machine using an aqueous solution containing lithium halide as an absorption liquid, wherein the absorption liquid contains an alkali metal hydroxide compound of 0.0
5 to 0.5% by weight, and cobalt compound 0.005 to 0.
1% by weight and 0.005 to 0.1% by weight of an antimony compound are contained. Here, the alkali metal hydroxide compound is lithium hydroxide, the cobalt compound is cobalt chloride, and the antimony compound is antimony trioxide.

At least 0.05% by weight of lithium hydroxide and 0.005% by weight of cobalt chloride and antimony trioxide are required. On the contrary, if the concentration is too high, alkali corrosion will occur or precipitation will occur without being completely dissolved. Lithium hydroxide is limited to 0.5 wt% and cobalt chloride and antimony trioxide are limited to 0.1 wt% because problems occur.

[Action]

By adding lithium hydroxide to an aqueous solution containing lithium halide, the hydrogen ion concentration of the solution is lowered and the corrosiveness is weakened. Further, by adding cobalt chloride, the anodic reaction of the metal exposed to the corrosive environment can be suppressed and the elution of the metal into the solution can be prevented. That is, since the metal corrosion reaction itself is suppressed, the generation of hydrogen gas accompanying the corrosion can also be suppressed. Further, antimony trioxide is adsorbed on the metal surface, has a function of protecting the metal surface, and brings about a stronger corrosion inhibiting effect.

〔Example〕

An aqueous solution containing 60% by weight of an aqueous lithium bromide solution was prepared, and lithium hydroxide was added to this aqueous solution as shown in Table 1.
Sample No. 1 containing cobalt chloride and antimony trioxide
~ 5 absorption solutions were prepared. The weight of the tested corrosion material is 65.5g, and the size is 11.0cm (length) x 4.0cm (width).
A carbon steel (spcc) of 0.2 cm (thickness) was prepared. A suspension hole was formed in this, and the surface of the test piece was polished with emery paper to perform degreasing treatment. After that, sample No. 1 to 1 in Table 1
Add 5 test pieces to each absorption solution containing the inhibitor shown in 5.
The pieces were separated and hung and dipped. Next, the inside of the container is evacuated, and heat treatment is performed at a temperature of 160 ° C. for 500 hours. After cooling, the inside of the container is evacuated again, the amount of gas generated by the corrosive reaction is measured, and the test piece is taken out. The corrosion weight loss was measured. The results are shown in Table 1.

It can be seen from Table 1 that the absorption liquid for an absorption refrigerating machine in which lithium hydroxide, cobalt chloride and antimony trioxide as additives were added to an aqueous solution of lithium bromide can reduce the amount of corrosion of carbon steel and the amount of generated gas.

For comparison, the same test as in Table 2 was carried out. No additives (No. 1), lithium hydroxide and lithium chromate (No.
2), lithium hydroxide and lithium molybdate (No.
3), the results of lithium hydroxide and lithium nitrate (No. 4) are shown. From Table 1 and Table 2 of Comparative Example, the absorption liquid for the absorption refrigerating machine in which lithium hydroxide and cobalt chloride were added to the aqueous solution of lithium bromide as additives from the table, the corrosion amount of carbon steel and the generated gas amount were remarkably reduced. It is clear to get. Further, by adding antimony trioxide to the absorbing liquid, it becomes possible to further reduce the amount of corrosion and the amount of generated gas.

[Effect of the invention] Since the absorption liquid for an absorption refrigerator of the present invention is an absorption liquid obtained by adding an alkali metal hydroxide compound, particularly lithium hydroxide, and a cobalt compound, especially cobalt chloride, to an aqueous solution containing lithium halide, Since it has a corrosion inhibiting effect on metal materials and suppresses the amount of generated gas, it is possible to extend the life of the constituent materials of the refrigerator and maintain the performance for a long period of time. Furthermore, by adding an antimony compound, especially antimony trioxide, to the absorption liquid, the corrosion inhibition and gas generation prevention effects can be further enhanced.

Claims (2)

[Claims] 1. An absorption liquid for an absorption refrigerator in which an aqueous solution containing lithium halide is used as an absorption liquid, wherein the absorption liquid contains 0.05 to 0.5% by weight of an alkali metal hydroxide compound and 0.005% of a cobalt compound. 0.1 to 0.1% by weight and an antimony compound in an amount of 0.005 to 0.1% by weight, an absorption liquid for an absorption refrigerator. 2. The absorption liquid for an absorption refrigerator according to claim 1, wherein the alkali metal hydroxide compound is lithium hydroxide, the cobalt compound is cobalt chloride, and the antimony compound is antimony trioxide.