KR100896518B1 - Composition for preventing corrosion anc scale of boiler and treatment method of water for boiler - Google Patents

Abstract

The present invention relates to a water treatment composition for preventing corrosion and scale of a boiler and a water treatment method using the same. In particular, the present invention relates to a water treatment composition comprising an acrylate polymer, a gluconate, a sulfite, and a hydroxide compound capable of effectively inhibiting corrosion and scale formation of a flow-through type boiler in which calcium ions are introduced in an amount of 1 ppm or more.

Boiler, Corrosion, Scale

Description

Technical Field [0001] The present invention relates to a water treatment composition for preventing corrosion and scale of a boiler, and a water treatment method using the same. BACKGROUND ART [0002]

[Technical Field]

The present invention relates to a water treatment composition for preventing corrosion and scale of a boiler and a water treatment method using the water treatment composition. More particularly, the present invention relates to a water treatment composition comprising an acrylate polymer, a gluconate, a sulfite and a hydroguyer, And to a method for treating water for inhibition.

BACKGROUND ART [0002]

Corrosion and scale are likely to be generated on heat transfer surfaces in contact with the boiler feed water, especially on the heat transfer surfaces of metallic materials, for various industrial installations requiring boiler water, or for buildings where boiler water is used for heating. The generated scale interferes with the smooth circulation of the boiler water, which reduces the thermal efficiency of the boiler and, in severe cases, causes serious rupture of the pipe.

The corrosion phenomenon can be explained by the rusting of the metal material. In general, the metal is a substance made of oxide in the process of recrystallization, so it has a very strong property of returning to a thermodynamically stable oxide state. It is therefore natural that corrosion occurs in boilers made of these metals.

The scale phenomenon is mainly caused by the introduction of bivalent metal components such as calcium and magnesium into the boiler feedwater together with anions. The inflow of the 2-valent metal component can be regarded as two cases in which the raw water is directly used as the boiler feed water without the water softener, and the inflow occurs because the bivalent metal component is not completely removed in spite of the water softener. Calcium carbonate and calcium phosphate are the most abundant scales generated by the influx of the divalent metal components, and all of them have a physical property of lowering the solubility with increasing temperature, Causing various problems.

A water treatment program to prevent the scale of this type of flow boiler has sedimentation type and non-sedimentation type, sedimentation types include carbonate program and phosphate program, and non-sediment type chelate program (Chemical Engineering / August 15, 1988) .

The carbonate program in the above program has been used for a long time to prevent calcium sulfate scale formation in the boiler where the pressure is below 150 psig and the hardness component of the water is about 50 ppm. However, at a boiler pressure of 150 psig or more, the sodium carbonate is decomposed into sodium hydroxide and carbon dioxide, and the scale control ability is lost. The decomposed carbon dioxide is dissolved in the condensed water, causing corrosion of the condensed water line.

The chelation program is effective at pressures up to 1,300 psig, where the calcium hardness of the feedwater is less than 1.5 ppm, but it is very difficult to apply because of the high corrosivity of the chelate compound. For example, if the chelate concentration is low, the ability to control the scale is lost due to the lack of a threshold function, and if the chelate concentration is high, the chelate will cause corrosion.

The phosphate program is the most widely used boiler water treatment program currently in use with polymers to float and remove calcium phosphate. However, in the case of water quality in which the concentration calcium hydroxide hardness of the irrigation water is 50 ppm or more, the performance of the program is rapidly deteriorated and the calcium phosphate scale is increased.

Accordingly, it is an object of the present invention to provide a water treatment agent composition for a perfume-type boiler excellent in corrosion and scale prevention function.

Another object of the present invention is to provide a method of inhibiting corrosion and scale of a flow-through type boiler using a water treatment composition excellent in corrosion and scale prevention.

The present invention

(a) an acrylate-based polymer represented by the formula (1);                     

(b) gluconate;

(c) sulfite and

(d) Hydroxide compound

And a water-treating agent composition for preventing corrosion and scale of the boiler.

The present invention also provides a method for water treatment of a boiler comprising introducing said water treatment composition into a water system of a boiler system.

Hereinafter, the present invention will be described in detail.

The inventors of the present invention have completed the present invention by developing a water treatment agent composition which is excellent in corrosion and scale prevention of a flow-through type boiler by eliminating phosphorus or phosphate used in a composition for preventing corrosion and scale of a conventional boiler.

The water treatment composition for corrosion and scale prevention of the boiler of the present invention comprises an acrylate-based polymer, a gluconate, a sulfite, and a hydroxide.

The (a) acrylate polymer of the present invention may be an acrylate polymer represented by the following formula (1).

(Formula 1)

In Formula 1,

l is 1 to 1,000,

m is from 0 to 1,000,

R is hydrogen, methyl or carboxyl group,

R ₁ and R ₆ are each independently hydrogen, an alkyl group or a hydroxy group,

R ₂ and R ₃ are each independently hydrogen or alkyl having 1 to 2 carbon atoms,

R < ₄ > is hydrogen or alkyl of 1 to 5 carbon atoms,

R ₅ is alkyl having 1 to 10 carbon atoms,

X and Y are each independently hydrogen, alkyl of 1 to 5 carbon atoms, or hydroxyalkyl of 1 to 5 carbon atoms.

When R is a carboxyl group, the compound of formula (1) may be bonded to an adjacent carboxyl group to form an anhydrous ring.

 The acrylate polymer of the present invention may be contained in the water treatment composition in an amount of 0.1 to 30% by weight. When the content is less than 0.1% by weight, the effect of preventing corrosion and scale may be insignificant. When the content is more than 30% by weight, . The acrylate-based polymer may be used alone or in a mixture of one or more kinds in the water treatment composition. Preferably, the acrylate-based compound is selected from the group consisting of an acrylate homopolymer, an acrylate copolymer, and mixtures thereof.

The (b) gluconate of the present invention may be selected from the group consisting of sodium gluconate, potassium gluconate, and mixtures thereof. The gluconate may be contained in the water treatment composition in an amount of 0.1 to 20% by weight. When the content of gluconate is less than 0.1% by weight, the effect of use may be insignificant. When the content of gluconate is more than 20% by weight, Adverse effects can be caused.

The sulfite (c) of the present invention may be selected from the group consisting of sodium sulfite, potassium sulfite, and mixtures thereof. The sulfite may be contained in the water treatment composition in an amount of 0.1 to 30% by weight. If the sulfite content is less than 0.1% by weight, the oxygen removal effect may be insufficient. If the sulfite content is more than 30% by weight, the storage stability of the water treatment composition .

The (d) hydroxide compound of the present invention is preferably sodium hydroxide or potassium hydroxide, and the above hydroxide compound may be used alone or in combination. The content of the hydroxide compound in the water treatment composition may be from 0.01 to 10% by weight, and since the hydroxide compound is used to vary the pH of the water treatment composition, if the content is outside the above range, the preferable pH range of the water treatment composition You can escape.

The water treatment composition according to the present invention may contain residual water in addition to the acrylate-based polymer, gluconate, sulfite, and hydroxide.

The present invention also provides a boiler water treatment method capable of inhibiting corrosion and scale formation of a boiler using the above water treatment composition.

The boiler may be a perfume-type boiler, and a boiler with a steam pressure of at most 40 KG is preferred. In addition, it can be used in a system where the calcium hardness of the boiler feedwater is at least 1 ppm or more, and it is possible to confirm the excellent corrosion prevention effect of the boiler and the formation of scales.

The water treatment composition of the present invention can be used according to the method of using the conventional boiler water treatment composition. For example, corrosion and scale formation of the boiler can be suppressed by supplying the boiler water to the boiler feed water. When the water treatment composition of the present invention is applied to a water treatment program, the water treatment composition is preferably maintained at a concentration of 1 to 500,000 ppm in the boiler water.

Hereinafter, examples of the present invention will be described. The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example: Preparation of Water Treatment Agent Composition

Good-Rite K-776 (Goodrich) and Acumer 1100 (Rohm & Haas) were used as the acrylate-based polymer, sodium gluconate, sulfite sodium sulfite with gluconate and potassium hydroxide as the hydroxide compound , And a water treatment agent composition was prepared in the composition ratio (unit: wt%) shown in Table 1 below.

ingredient Example 1 Example 2 Example 3  Good-Rite K-776 2.0 2.5 3.0  Accumer 1100 1.0 1.5 2.0  Sodium gluconate 4.0 5.0 2.5  Sodium sulfite 6.0 7.5 5.0  Potassium hydroxide 1.0 1.5 0.5  water up to 100 up to 100 up to 100

Experimental Example 1: Verification of corrosion prevention effect of boiler

Corrosion experiments were carried out using an autoclave.

The weight loss of carbon steel was measured at a temperature of 121 ° C and a pressure of 1.5 KG. The carbon steel used was a low carbon steel having a carbon content of 0.18%.

The water treatment composition of the present invention was dissolved and maintained at the concentrations shown in Table 3 in the water quality shown in Table 2 below, and the weight loss of the carbon steel was measured by immersing the carbon steel for 30 minutes. As a comparative group, the same test was carried out by dissolving in water at the concentrations shown in Table 3 below.

Water quality Water quality # 1 Water quality # 2 Water quality # 3 PH 10.0 ± 0.5 Calcium Hardness (ppm) 50 100 150 Overall Diameter (ppm) 60 120 180 Chloride ion (ppm) 35.5 71 106.5

The pH of the water was adjusted by using 0.1 N, 0.5 N, 1 N aqueous sodium hydroxide solution and 0.1 N, 0.5 N, 1 N sulfuric acid aqueous solution. The calcium hardness was adjusted to be calcium chloride, and the total hardness was the magnesium hardness content added to calcium hardness Were calculated and adjusted with magnesium sulfate, respectively.

ingredient Content (ppm) Experiment 1 Experiment 2 Experiment group 3 Comparison group 1 Comparison group 2 Comparison group 3  Good-Rite K-776 25 50 75 - 5 -  Accumer 1100 15 30 45 - - 5  Sodium gluconate 50 100 150 - 5 -  Sodium sulfite 75 150 225 - - 5  Potassium hydroxide 15 30 45 - One One

The corrosion test results measured by the above method are shown in Table 4 below.                     

Weight loss (mg) Water quality # 1 Water quality # 2 Water quality # 3 Experiment 1 1.6 1.4 0.9 Experiment 2 0.6 0.5 0.4 Experiment group 3 0.3 0.3 0.1 Comparison group 1 10.1 8.9 8.8 Comparison group 2 6.2 5.9 5.7 Comparison group 3 5.4 5.6 5.3

As can be seen from Table 4, when the water treatment composition of the present invention was used, the corrosion inhibition effect was much better than that of Comparative Groups 1 to 3, and the water treatment composition of the Example was stable even in a mixed state and excellent in storage stability.

Experimental Example 2: Verification of Scale Formation Inhibition Effect of Boiler

The laboratory standard method for accurately evaluating the scale suppression capability of the boiler is as follows. (Corrosion / 96 Paper No. 158, U.S. Patent No. 4,925,568)

Experimental water quality as shown in Table 5 was prepared in a bottle with a 200 ml lid. The water treatment composition of the example was dissolved at the concentration shown in Table 3, the pH was adjusted to 9.15, and then 20 hours Scale inhibition experiments were performed in an oven. The calcium hardness of the experimental water was controlled by calcium chloride, and the M-alkalinity was controlled by sodium bicarbonate and sodium carbonate. The same test was conducted by dissolving the compound in the experimental water at the concentrations shown in Table 3 as comparative groups.

Water quality concentration (ppm) Calcium hardness 500 M-alkalinity 500 Chlorine ion 355

After 20 hours, the mixture was cooled at room temperature, filtered through a 0.45 μm filter, and calcium hardness was measured and converted to calcium transportation value.

Calcium transport value is a measure of how many percent of the hardness components of the feedwater are removed by blowdown when the concentrate is concentrated in boiler water. If the transport value is 100, the concentrated hardness components are attached to the scale And 80% means that 20% is attached to the boiler surface in scale.

(Equation 1)

Calcium Transport Value (%) =

Hardness component concentration after experiment (ppm) / Hardness component concentration before experiment (ppm) X 100

The scale inhibition test results of the water treatment composition of the present invention are shown in Table 6 below.

division Calcium Transport Value (%) Experiment 1 90 Experiment 2 93 Experiment group 3 95 Comparison group 1 33 Comparison group 2 73 Comparison group 3 75

In Table 6, experimental groups 1 to 3 using the water treatment composition of the present invention show that the scale formation of the boiler is very low as compared with the comparison group, effectively suppressing scale formation.

 As mentioned above, the present invention provides a water treatment agent composition for preventing corrosion and scaling of a boiler, thereby effectively suppressing corrosion and scale formation of the boiler. In particular, corrosion and scale formation The problems caused by corrosion and scale can be solved.

Claims (8)

(a) an acrylate-based polymer represented by the formula (1); (b) gluconate; (c) sulfite and (d) Hydroxide compound Waterborne composition for boiler corrosion and scale inhibition comprising: (Formula 1)

In Formula 1, l is 1 to 1,000, m is from 0 to 1,000, R is hydrogen, methyl or carboxyl group, R ₁ and R ₆ are each independently hydrogen, an alkyl group or a hydroxy group, R ₂ and R ₃ are each independently hydrogen or alkyl having 1 to 2 carbon atoms, R < ₄ > is hydrogen or alkyl of 1 to 5 carbon atoms, R ₅ is alkyl having 1 to 10 carbon atoms, X and Y are each independently hydrogen, alkyl of 1 to 5 carbon atoms, or hydroxyalkyl of 1 to 5 carbon atoms. The water treatment composition according to claim 1, wherein the acrylate-based polymer is selected from the group consisting of an acrylate homopolymer, an acrylate-based copolymer, and a mixture thereof. The water treatment composition according to claim 1, wherein the water treatment agent composition comprises 0.1 to 30% by weight of an acrylate based polymer, 0.1 to 20% by weight of gluconate, 0.1 to 30% by weight of sulfite, 0.01 to 10% by weight of hydroxyl, By weight of water. The water treatment composition of claim 1, wherein the gluconate is selected from the group consisting of sodium gluconate, potassium gluconate, and mixtures thereof. The water treatment composition of claim 1, wherein the sulfite is selected from the group consisting of sodium sulfite, potassium sulfite, and mixtures thereof. The water treatment composition of claim 1, wherein the hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof. A method for water treatment of a boiler comprising introducing the water treatment composition according to any one of claims 1 to 6 into the water system of the boiler system. The boiler water treatment method according to claim 7, wherein the water treatment agent composition is added to the water system at 1 ppm to 500,000 ppm.