KR100315496B1 - Method for Inhibiting Corrosion of Boiler Condensation System Using Corrosion Inhibiting Composition - Google Patents

Abstract

PURPOSE: A corrosion inhibiting composition for preventing the corrosion of boiler condensation system due to dissolved oxygen and carbon dioxide, and a method for preventing corrosion of boiler condensation system using the same are provided. CONSTITUTION: The corrosion inhibiting composition comprises 0.1 to 10 wt.% of diethyl hydroxyl amine represented by formula I; 0.1 to 20 wt.% of diethylethanolamine represented by formula II; 0.1 to 20 wt.% of morpholine represented by formula III; 0.1 to 40 wt.% of cyclohexylamine represented by formula IV; and a balance of water. The method for preventing corrosion of boiler condensation system using the corrosion inhibiting composition is characterized in that the boiler condensation system is operated to contain 0.05 to 5 ppm of diethyl hydroxyl amine, 2 to 15 ppm of diethylethanolamine, 2 to 20 ppm of morpholine and 3 to 20 ppm of cyclohexylamine.

Description

Method for Inhibiting Corrosion of Boiler Condensation System Using Corrosion Inhibiting Composition}

The present invention relates to a corrosion inhibitor for a boiler and a method for inhibiting corrosion of a boiler condensation system using the same, and more particularly, a mixture of a deoxidizer, a basicity (Basic), and a Neutralizing Capacity. In particular, the present invention relates to a corrosion inhibitor for a boiler capable of simultaneously performing oxygen removal and corrosion prevention of a condensation system as a single product, and a corrosion suppression method of a boiler condensation system using the same.

The study of deoxidizers to remove oxygen from boiler water has been undertaken for a long time because dissolved oxygen is the most extensively corrosive substance throughout the boiler.

The removal of dissolved oxygen from the boiler water prevents the corrosion caused by oxygen, so deoxygenation for this purpose is primarily performed in feedwater and irrigation and often contains oxygen above the reference level (25 ppb) in the condensation system. Sometimes it is added for the purpose of removing oxygen from the condensation part.

Steam generated from various industrial boilers used for process heat exchange and power generation is generally condensed and used to recover the boiler feedwater in terms of energy and water consumption. Therefore, in sites with boilers, efforts are made to increase the recovery of condensate whenever possible.

However, in the heat exchanger and condensation line in which such condensate is generated, the overall pH of the condensate is dissolved in the condensate as carbon dioxide generated by pyrolysis of M-alkalido (sodium carbonate and sodium bicarbonate) contained in the boiler feed water is dissolved in the condensate. Will drop.

Corrosion of the condensation system caused by this phenomenon is generally referred to as carbon dioxide corrosion, which is characterized by thinning of the metal surface as a whole, unlike pitting, in which small portions of the metal surface are concentrated.

The amount of carbon dioxide generated in steam varies according to the M-alkali of the water supply, the operating pressure of the boiler, and the concentration of the boiler. Generally, if the feed water is used as soft water (removing cations) and the condensate is not treated, the pH of the condensate is about 5.5 to 6.5. Are exposed to the risk of carbon dioxide corrosion.

In particular, heat exchangers exposed to carbon dioxide for long periods of time are very threatening not only in steel but also in copper alloys and, in severe cases, can lead to heat exchanger rupture.

Condensate treatment agents used to prevent corrosion of such condensation systems must have sufficient volatility to reach all areas where steam and carbon dioxide reach, and must be able to condense and react together in all areas where condensation occurs.

Conventionally, a deoxidizer and a condensate treatment agent have been used as a water treatment agent to prevent the corrosion of oxygen and condensate water, and sodium sulfite, hydrazine, hydroquinone, etc. have been used as the deoxidizer, and volatile amine compounds have been used as the condensate treatment agent. Patent 5,094,814).

However, the above conventional water treatment composition has no significant difference in the anticorrosive effect when the oxygen concentration is less than the reference value in the condensation site, but the satisfactory effect is not expected when there is oxygen above the reference value in the condensation site. In all, there was a difficulty in adding deoxidant and condensate separately.

In addition, if the condensation system contains dissolved oxygen above the standard value, volatile deoxidizer should be added. Since the previously used sodium sulfite or hydroquinone is not volatile, it cannot reach the condensate line when it is added to the water supply line, and hydrazine is volatile. However, high pressure boilers of 50kg or more have a high rate of decay into ammonia, so if copper alloys are present, they are exposed to eastern hazards.

Therefore, the present invention completely improves the drawbacks of the conventional deoxidizer for condensate treatment and the method of adding the deoxidizer and the condensate treatment agent, so that the deoxidizer also uses volatile substances such as volatile amines, which have been used in the past. The purpose of the product is to provide a water treatment composition that can perform an effective anticorrosive function in the oxygen corrosion and condensation of all parts of the boiler.

It is another object of the present invention to provide a method of suppressing corrosion of a boiler condensation system by applying the composition at a suitable concentration in a boiler water system.

The composition of the present invention for achieving the above object is 0.1 to 10% by weight of diethylhydroxylamine represented by the following formula (1), diethylethanolamine represented by the following formula (2) in the composition for preventing the initial condensation zone corrosion of the condensation system 0.1 to 20% by weight, 0.1 to 20% by weight of the morpholine represented by the following formula (3), 0.1 to 40% by weight of the cyclohexylamine represented by the following formula (4) and the remainder are water.

Corrosion suppression method of the present invention for achieving the above another object is that in applying the composition to the boiler water system, the diethyl hydroxylamine is maintained at 0.05 to 5ppm, diethylethanolamine is 2 to 15ppm when the water treatment program is applied And morpholine is maintained at 2-20 ppm, and cyclohexylamine is added so as to be maintained at 3-20 ppm.

Looking at the present invention in more detail as follows.

The composition according to the present invention has good deoxygenation at low and high temperatures as a deoxidant, and has a high vaporization rate (V / L Ratio), which is effective for removing oxygen from the condensation system. Use weight percent.

In addition, as a volatile amine used in the present invention, 0.1 to 20% by weight of diethylethanolamine represented by Formula 2, 0.1 to 20% by weight of morpholine represented by Formula 3, and cyclohexylamine represented by Formula 4 0.1 to 40% by weight is used and the remainder consists of water.

If the amount of diethylhydroxylamine represented by the formula (1) is less than 0.1% by weight, the deoxygenation function is lowered, and if the amount of diethylhydroxylamine is more than 10% by weight, it is uneconomical, and the amount of diethylethanolamine represented by the formula (2) is 0.1 If the weight percentage is less than the medium-term condensation system method is insufficient, if it exceeds 20% by weight has an uneconomical disadvantage. In addition, when the amount of morpholine represented by the formula (3) is less than 0.1% by weight, the initial condensation system method is insufficient, and when it exceeds 20% by weight, it is uneconomical, and the amount of the cyclohexylamine represented by the formula (4) is 0.1% by weight. If it is less than%, the terminal condensation system method is insufficient, and if it exceeds 40% by weight, there is an uneconomical disadvantage.

When applying the condensate treatment composition as described above to the condensation system of the boiler, it is preferable to adjust the pH to be maintained at 8.5 to 9.0 in all areas of the condensation system, it is preferable to completely remove the dissolved oxygen as possible.

Therefore, in applying the water treatment agent composition of the present invention to the boiler water system, the diethylhydroxylamine represented by Chemical Formula 1 is maintained at 0.05 to 5 ppm when the water treatment program is applied, and the diethylethanolamine represented by Chemical Formula 2 is 2 to Maintained at 15ppm, morpholine represented by the formula (3) is maintained at 2 to 20ppm. In addition, the cyclohexylamine represented by Formula 4 is maintained at 3 to 20ppm.

At this time, if the concentration of diethylhydroxylamine represented by the formula (1) is outside the range of 0.05 to 5ppm deoxygenation function is insufficient, if the concentration of diethylethanolamine represented by the formula (2) is less than 2ppm corrosion protection function It is inadequate and exceeds 15 ppm, which is uneconomical. In addition, when the concentration of the morpholine represented by the formula (3) is less than 2ppm, the anticorrosive function is inadequate, and if the concentration of the morpholine exceeds 20ppm is uneconomical, the concentration of the cyclohexylamine represented by the formula (4) is outside the range of 3 to 20ppm There is a drawback of lack of anticorrosive function.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Examples 1-2

The boiler drum pressure is 90kgf / cm ² , the capacity is 50 ton / hr, and the condensate recovery rate is 30 and the condensate recovery rate is 30, using a power plant water-type boiler system that uses pure water completely free of positive and negative ions. The drive was run for 30 days, adjusting to%.

At this time, to prepare a water treatment agent composition consisting of the composition shown in Table 2 in the water quality of the feed water as shown in Table 1, added to the feed line at a rate of 5mg per 1kg of steam generation and deoxidizer, pH, iron concentration of the water supply and condensation system It is shown in Table 4 below.

Item Contents pH 6.0 Conductivity (μS / cm) 0.5 Calcium hardness (ppm) 0.0 Chlorine Concentration (ppm) 0.0. Silica (ppm) 0.02 Dissolved oxygen, degassing outlet (ppb) 30

The usual reference value of dissolved oxygen is 15-50 ppm, and the measurement of the said item was performed by the conventional method.

ingredient Content (wt%) Example 1 Example 2 water 58 55 Diethylhydroxylamine 3 5 Morpholine 10 15 Diethylethanolamine 10 5 Cyclohexylamine 19 20

Comparative Examples 1 to 3

To prepare the two water treatment agent products shown in Table 3, the deoxidizer and the condensate water treatment was tested by maintaining 0.3ppm and 5ppm compared to the water supply and steam generation to maintain the same concentration as in Examples 1 and 2 respectively The sweep, pH, and iron concentrations are shown in Table 4 below.

ingredient Content (% by weight) Comparative Example 1 Comparative Example 2 Comparative Example 3 Deoxidant water 50 60 50 Hydrazine 50 0 50 Hydroquinone 0 40 0 Condensate Treatment Agent water 60 60 65 Morpholine 10 10 0 Diethylethanolamine 10 10 0 Cyclohexylamine 20 20 0 ammonia 0 0 35

division rating Condensate pH Copper (ppm) Train (ppm) pH Copper (ppm) Train (ppm) Example 1 8.4-8.7 0.01 or less 0.01 or less 8.2-8.5 0.01 or less 0.01 or less Example 2 8.4-8.7 0.01 or less 0.01 or less 8.2-8.5 0.01 or less 0.01 or less Comparative Example 1 8.4-8.7 0.01 or less 0.02 or less 8.2-8.5 0.02 0.03 or less Comparative Example 2 8.4-8.7 0.01 or less 0.02 or less 8.2-8.5 0.02 0.03 or less Comparative Example 3 8.4-8.7 0.02 or less 0.02 or less 8.2-8.5 0.03 0.03 or less

According to Table 4, the pH of the water supply and condensation parts of Examples 1 to 2 according to the present invention for the water quality of Table 1 are maintained similarly, but the concentrations of the electric and copper representing the degree of corrosion are comparative examples 1 to 3 in the condensation system. It can be seen that it is kept lower. Accordingly, it can be seen that the concentration of corrosion products is kept relatively low even in the feedwater where the recovered condensate is collected.

This result is because Examples 1 and 2 effectively control the dissolved oxygen in the condensation system and coat the anticorrosive coating, and at the same time, no ammonia is sensitive to copper corrosion.

As described above, the composition of the present invention can exert an effect of equal or more by using a single product of the existing product to put the deoxidant and condensate, respectively, in particular dissolved oxygen is present in the condensation site or more than the reference value or the same material If present, the condensing system function is excellent.

Claims (1)

In the corrosion inhibiting method of the boiler condensation system, 0.1 to 10% by weight of diethylhydroxyl amine represented by the following formula (1), 0.1 to 20% by weight of diethylethanol amine represented by the following formula (2), When the composition consisting of 0.1 to 20% by weight of polyline, 0.1 to 40% by weight of cyclohexylamine represented by the following formula (4) and the rest of water is applied to the water treatment program of the boiler condensation system, the diethylhydroxylamine is maintained at 0.05 to 5 ppm. And diethylethanol amine maintained at 2-15 ppm, morpholine maintained at 2-20 ppm, and cyclohexyl amine maintained at 3-20 ppm. Corrosion Inhibition Method: Formula 1

Formula 2

Formula 3

Formula 4