JPH06184597A - Method for cleaning water circuit - Google Patents

Abstract

PURPOSE:To dispense with the neutralization of waste liquor to thereby shorten the cleaning time and to perform cleaning effectively in washing out the slime and sludge in a water circuit. CONSTITUTION:At least one amino acid and a molybdic acid compound are incorporated into hydrogen peroxide or its adduct, and the mixture is used for cleaning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning an aqueous circuit for cleaning slime and sludge in the aqueous circuit.

[0002]

2. Description of the Related Art Cooling water circuits for refrigerators and industrial plants,
For water system circuits such as hot and cold water circuits that use water as a heat medium,
Scale that is mainly composed of minerals such as hardness components and iron rust in water, sludge before solidification on scale, and slime that is mainly composed of organic substances of microorganisms (bacteria, algae, etc.) are generated,
They are attached individually or in a mixed state. If such dirt adheres to the water system circuit, various obstacles such as impairing the heat exchange performance and obstructing the flow of water to cause insufficient flow rate occur. Water system circuits are being cleaned to eliminate this obstacle. For the cleaning, a chemical cleaning method or a physical cleaning method using a resin brush or the like is adopted. When carrying out chemical cleaning using chemicals, hydrogen peroxide is mainly used for removing organic stains such as slime, and acid is used for removing scale.

On the other hand, for cleaning sludge, cleaning with hydrogen peroxide is mainly used, but the cleaning effect is small. This is because the sludge is a mixture of organic and inorganic substances, and is a highly sticky inorganic substance before it solidifies to scale. When hydrogen peroxide and an acid are mixed and used for cleaning sludge, severe corrosion occurs on the metal material of the pipe and the heat exchanger, but there is no effective method for preventing this corrosion. Therefore, it is not possible to use hydrogen peroxide and acid together because cleaning with hydrogen peroxide and acid causes corrosion damage. In some cases, a method of removing the organic matter and removing the organic matter subordinately may be adopted.

[0004]

However, such an individual cleaning method using hydrogen peroxide and an acid requires a great deal of cost and time, and a satisfactory cleaning effect cannot be obtained. Neutralizing anti-corrosion work of the water system circuit after cleaning and neutralization work of the waste liquid were not saved, and the cleaning work was troublesome.
Therefore, there is no effective and simple method for sludge until now, and the development of a cleaning method effective for slime and sludge and a cleaning method that does not require waste liquid neutralization after cleaning is awaited. I felt very inconvenient for the cleaning work.

[0005]

SUMMARY OF THE INVENTION The present invention does not provide a method for cleaning an aqueous circuit which eliminates such inconveniences, eliminates the need for waste liquid neutralization work, and shortens the cleaning time to effectively perform cleaning. It is what

That is, at least one or more substances selected from amino acids and a molybdic acid compound are added to hydrogen peroxide or a hydrogen peroxide-added compound for cleaning. The hydrogen peroxide and the hydrogen peroxide addition compound are not limited to these, but hydrogen peroxide, sodium percarbonate and the like can be exemplified. The amino acids include, but are not limited to, ethylenediaminetetraacetic acid, nitrotriacetic acid, β-alanine-N, N-diacetic acid, aminopalpitulic acid-N, N.
-Diacetic acid, aminobenzoic acid-N, N-diacetic acid, 1,2-
Diaminocyclohexane-N, N'-tetraacetic acid, trimethylenediaminetetraacetic acid, phosphoethylimino-
N, N-diacetic acid, sulfoethylimino-N, N-diacetic acid, aminomethylphosphonic acid-N, N-diacetic acid, N-hydroxyethylethylenediamine-N, N ′, N ″ -triacetic acid and the like. Examples thereof include alkali metal salts and ammonium salts. The molybdic acid compound is not limited to this, but examples thereof include alkali metal salts and ammonium salts of molybdic acid.

These three components may be added separately to the water, but it is more convenient in terms of work to add the amino acids and molybdate in a mixture. By adding these three components, the synergistic effect of exfoliating slime and sludge of hydrogen peroxide or hydrogen peroxide adduct, chelating amino acids and promoting decomposition of molybdate to decompose hydrogen peroxide etc. A cleaning effect that is several times that of using hydrogen alone can be obtained. Further, the effect of removing the hardness component and the metal component in the sludge can be obtained, and a part of the scale can be washed. Furthermore, the conventional cleaning time of 2 to 3 hours can be reduced to 1/2 to 1/3.

Regarding the concentration of addition, hydrogen peroxide or hydrogen peroxide-added compound is 0.1% in the water as hydrogen peroxide.
-20%, preferably 1-5%, amino acids 0.5-10%, preferably 1-3%, molybdate 0.1-10%, preferably 0.3.
~ 2%. In addition, an azole compound may be added as a corrosion inhibitor for the copper material to the cleaning of the present invention. Examples of the azole compound include benzotriazole, di (2-ethylhexyl) -aminomethyltolyltriazole, 5,5'-methylene-bis-benzotriazole, 1,2,4-triazole, and tolyltriazole.

[0009]

EXAMPLES Examples of the present invention will be described below. (Example 1) Calcium ion, magnesium ion, hydrogencarbonate ion, and ionic silica are contained in a circulation circuit having a thermostat having an open part and a copper tube having a diameter of 3/4 inch and a length of 30 cm which is heated by a mantle heater. The water was evaporated while replenishing the water, these ions were concentrated, and scale and sludge were produced and adhered to the heated copper tube, and the adhered scale and sludge were used for cleaning. Cleaning time is 1
It was time. The effect of cleaning was investigated by measuring the increasing concentration of the inorganic component before and after the cleaning. Example compositions are shown in Table 1, comparative composition examples are shown in Table 2, and measurement results are shown in Tables 3 and 4.

[0010]

[Table 1]

[0011]

[Table 2]

[0012]

[Table 3]

[0013]

[Table 4]

As is apparent from Tables 3 and 4, in this example, the increase in the concentration of calcium ion / magnesium ion / ionic silica during washing was higher than that in the comparative example, and the excellent effect was obtained. Is recognized. In addition, after washing with Example Composition Example A of the present example, when further washing with sulfamic acid 10% for 2 hours, the increase in the concentration of each ion was
Calcium concentration 10.9 mg / l, magnesium concentration 1
The concentration is 6.9 mg / l and the ionic silica concentration is 0.1 mg / l, and this example has an effect of removing sludge and a part of scale.

(Example 2) Slime (algae) adhering to and adhering to a glass spiral condenser using ground water was washed for 1 hour, and the removal rate of slime (algae) was visually determined. An example of the composition of the composition is shown in Table 4, an example of the composition of the comparison is shown in Table 5, and the test results (removal rate) are shown in Tables 6 and 7.

[0016]

[Table 5]

[0017]

[Table 6]

[0018]

[Table 7]

[0019]

[Table 8]

As is clear from Tables 6 and 7, the method of the present invention has a more excellent slime (algae) removing effect than hydrogen peroxide alone. Further, when the cleaning time is 1 hour, the cleaning effect of hydrogen peroxide is hardly recognized, but according to the present invention, the cleaning effect is sufficiently recognized by the cleaning for 1 hour.

[0021]

As described above, according to the present invention, the excellent cleaning effect on sludge is recognized, the neutralization of the waste liquid after cleaning is unnecessary, and the slime is treated by hydrogen peroxide alone. It has many advantages such as excellent cleaning effect can be obtained in a shorter time than cleaning, and cleaning work time can be shortened.
It is an excellent invention for industrial use.

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Claims (1)

[Claims] 1. A water-based circuit characterized in that at least one substance selected from amino acids and a molybdic acid compound are added to hydrogen peroxide or a hydrogen peroxide-added compound for cleaning. Cleaning method.