A closed circulating water system soft water corrosion inhibitor and preparation method thereof

Abstract

The present invention discloses a closed-circulation water system softening water corrosion inhibitor and its preparation method, relating to the field of water treatment technology. The softening water corrosion inhibitor comprises the following raw materials by weight: 40-80 parts of a macromolecular amino acid compound, 80-100 parts of zinc chloride, 200-300 parts of borax, and 300-400 parts of deionized water. The softening water corrosion inhibitor disclosed in the present invention exhibits excellent corrosion inhibition, maintains its effect for a long time, is inexpensive, and exhibits a corrosion rate of less than 0.020 mm / a.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and in particular to a soft water corrosion inhibitor for a closed circulating water system and a preparation method thereof. Background Art

[0002] In the field of water treatment circulating water, most are open circulating water cooling systems, but some are closed circulating water systems. Closed systems often use soft water to circulate in the system. The extremely low conductivity and ion content make scaling and microbial contamination almost non-existent. However, due to the ultra-low conductivity, dissolved oxygen and carbon dioxide have the effect of promoting metal corrosion, thereby promoting metal corrosion, so it is necessary to add a special soft water corrosion inhibitor to protect the circulating water system. Many people believe that soft water has very few impurity ions and is not corrosive, but in reality, experiments have found that the corrosiveness of soft water is even higher than that of tap water. Therefore, in a closed soft water system, the addition of a corrosion inhibitor is very necessary. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention aims to provide a soft water corrosion inhibitor for a closed circulating water system and a preparation method thereof.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A closed circulating water system softening water corrosion inhibitor, comprising a macromolecular amino acid compound of the structural formula shown in formula (I),

[0006]

[0007] The macromolecular amino acid compound is prepared by the following method:

[0008] S1: Methanol and triethylenetetramine were added to the reactor in sequence and stirred to mix. Under nitrogen protection, 2,4-pentadienoic acid was slowly added at a constant temperature of 30±5°C for 2-3 hours. The reaction was continued for 18-24 hours. Then, the mixture was distilled under reduced pressure at 50±5°C and 133 Pa to obtain a light yellow oily liquid. The reaction equation is as follows:

[0009]

[0010] S2: Add thiourea acetic acid solution to the light yellow oily liquid, heat to 40-60°C, stir and react for 3-5 hours, cool to room temperature, precipitate solid, filter, wash with water, and vacuum dry to obtain the product. The reaction equation is as follows:

[0011]

[0012] The mass ratio of the methanol to the triethylenetetramine is 4:1, and the molar ratio of the triethylenetetramine to 2,4-pentadienoic acid is 1:(7-8).

[0013] The molar ratio of thiourea to triethylenetetramine is (6-7):1.

[0014] Furthermore, a closed circulating water system softening corrosion inhibitor comprises the following raw materials in parts by weight:

[0015] 40-80 parts of macromolecular amino acid compound, 80-100 parts of zinc chloride, 200-300 parts of borax, and 300-400 parts of deionized water.

[0016] The effective content of the borax is ≥90.0 wt%.

[0017] A method for preparing a soft water corrosion inhibitor for a closed circulating water system comprises the following steps:

[0018] S1: Weigh the macromolecular amino acid compound, zinc chloride, borax, and deionized water according to the ratio;

[0019] S2: Add the weighed deionized water, macromolecular amino acid compound, zinc chloride and borax into a stirring tank in sequence, stir at 40-50° C. for 30-60 minutes, and filter to obtain a closed circulating water system soft water corrosion inhibitor.

[0020] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0021] (1) The soft water corrosion inhibitor for a closed circulating water system disclosed in the present invention has good corrosion inhibition effect, can maintain the effect for a long time, is low in price, and has a corrosion rate of less than 0.020 mm / a;

[0022] (2) The soft water corrosion inhibitor for a closed circulating water system provided by the present invention can quickly form a protective film on the inner surface of the closed system through the synergistic effect of zinc ions and macromolecular amino acid compounds, and the macromolecular amino acid compounds play a role in repairing the zinc ion film.

[0023] (3) The soft water corrosion inhibitor for closed circulating water systems provided by the present invention has strong adaptability to carbon steel, stainless steel and copper closed system soft water systems, and can be widely used in the closed system soft water corrosion inhibitor market. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0025] Example 1

[0026] Preparation of macromolecular amino acid compounds:

[0027] S1: 4000 g of methanol and 1000 g of triethylenetetramine were added to the reactor in sequence, stirred and mixed, and 5000 g of 2,4-pentadienoic acid was slowly added at a constant temperature of 30±5°C under nitrogen protection for 2.5 h. The reaction was continued for 20 h, and then the mixture was distilled under reduced pressure at 50±5°C and 133 Pa to obtain a light yellow oily liquid.

[0028] S2: Add thiourea acetic acid solution (3300 g thiourea mixed with 5000 g acetic acid) to the light yellow oily liquid, heat to 50°C, stir and react for 4 hours, cool to room temperature, precipitate solid, filter, wash with 500 g deionized water, and dry in vacuum at 50°C to obtain.

[0029] Example 2

[0030] Preparation of macromolecular amino acid compounds:

[0031] S1: 4000 g of methanol and 1000 g of triethylenetetramine were added to the reactor in sequence and stirred to mix. Under nitrogen protection, 4696 g of 2,4-pentadienoic acid was slowly added at a constant temperature of 30±5°C for 2 h. The reaction was continued for 18 h. The mixture was then distilled under reduced pressure at 50±5°C and 133 Pa to obtain a light yellow oily liquid.

[0032] S2: Add thiourea acetic acid solution (3124 g thiourea mixed with 5000 g acetic acid) to the light yellow oily liquid, heat to 40 ° C, stir and react for 5 hours, cool to room temperature, precipitate solid, then filter, wash with 500 g deionized water, and dry in vacuum at 50 ° C to obtain.

[0033] Example 3

[0034] Preparation of macromolecular amino acid compounds:

[0035] S1: 4000 g of methanol and 1000 g of triethylenetetramine were added to the reactor in sequence and stirred to mix. Under nitrogen protection, 5367 g of 2,4-pentadienoic acid was slowly added at a constant temperature of 30±5°C for 3 hours. The reaction was continued for 24 hours. The mixture was then distilled under reduced pressure at 50±5°C and 133 Pa to obtain a light yellow oily liquid.

[0036] S2: Add thiourea acetic acid solution (3644 g thiourea mixed with 5000 g acetic acid) to the light yellow oily liquid, heat to 60 ° C, stir and react for 3 hours, cool to room temperature, precipitate solid, then filter, wash with 500 g deionized water, and dry in vacuum at 50 ° C to obtain.

[0037] Example 4

[0038] Preparation of soft water corrosion inhibitor for closed circulating water system:

[0039] S1: Weigh 60 kg of the macromolecular amino acid compound (prepared in Example 1), 90 kg of zinc chloride, 250 kg of borax (93.1 wt%), and 350 kg of deionized water;

[0040] S2: Add the weighed deionized water, macromolecular amino acid compound, zinc chloride, and borax into a stirring tank in sequence, stir at 45° C. for 45 minutes, and filter through a 100-mesh filter to obtain a soft water corrosion inhibitor for a closed circulating water system.

[0041] Example 5

[0042] Preparation of soft water corrosion inhibitor for closed circulating water system:

[0043] S1: Weigh 40 kg of the macromolecular amino acid compound (prepared in Example 2), 80 kg of zinc chloride, 200 kg of borax (93.1 wt%), and 300 kg of deionized water;

[0044] S2: Add the weighed deionized water, macromolecular amino acid compound, zinc chloride, and borax into a stirring tank in sequence, stir at 40° C. for 30 minutes, and filter through a 100-mesh filter to obtain a soft water corrosion inhibitor for a closed circulating water system.

[0045] Example 6

[0046] Preparation of soft water corrosion inhibitor for closed circulating water system:

[0047] S1: Weigh 80 kg of the macromolecular amino acid compound (prepared in Example 3), 100 kg of zinc chloride, 300 kg of borax (93.1 wt%), and 400 kg of deionized water;

[0048] S2: Add the weighed deionized water, macromolecular amino acid compound, zinc chloride, and borax into a stirring tank in sequence, stir at 50° C. for 60 minutes, and filter through a 100-mesh filter to obtain a soft water corrosion inhibitor for a closed circulating water system.

[0049] Comparative Example 1

[0050] The preparation method of the soft water corrosion inhibitor for the closed circulating water system is basically the same as that of Example 4, except that the macromolecular amino acid compound (prepared in Example 1) is replaced by an equal amount of the light yellow oily liquid prepared in step S1 of Example 1.

[0051] Comparative Example 2

[0052] The preparation method of the soft water corrosion inhibitor for a closed circulating water system is basically the same as that of Example 4, except that the macromolecular amino acid compound (prepared in Example 1) is replaced by an equal amount of hydroxyethylidene diphosphonic acid.

[0053] Comparative Example 3

[0054] The preparation method of the soft water corrosion inhibitor for the closed circulating water system is basically the same as that of Example 4, except that the macromolecular amino acid compound (prepared in Example 1) is replaced by an equal amount of polyaspartic acid.

[0055] The corrosion inhibitors prepared in the examples of the present invention and the comparative examples were subjected to corrosion inhibition performance tests. The main water quality indicators of the test water samples are shown in Table 1. The test was performed at dosage concentrations of 10 mg / L and 20 mg / L, a test magnification of 8.0, and a standard corrosion coupon made of 20# carbon steel. The test procedure was conducted in accordance with GB / T18175-2014. The test results are shown in Table 2.

[0056] Table 1

[0057] Conductivity (25℃) 5μS / cm <![CDATA[Cl - ]]> 1.1mg / L pH 7.62 <![CDATA[Mg 2+ ]]> 0mg / L <![CDATA[Ca 2+ ]]> 0mg / L <![CDATA[HCO3 - ]]> 1.3mg / L <![CDATA[CO3 2- ]]> 0mg / L <![CDATA[Na + ]]> 2.4mg / L

[0058] Table 2

[0059]

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in this field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the scope of protection of the technical solution of the present invention.

Claims

1. A closed circulating water system soft water corrosion inhibitor, characterized in that: The raw materials include the following parts by weight: 40-80 parts of a macromolecular amino acid compound of the structural formula shown in formula (I), 80-100 parts of zinc chloride, 200-300 parts of borax, and 300-400 parts of deionized water; （I）。 2. A closed circulating water system soft water corrosion inhibitor according to claim 1, characterized in that: The macromolecular amino acid compound is prepared by the following method: S1: Methanol and triethylenetetramine were added to the reactor in sequence and stirred to mix. Under nitrogen protection, 2,4-pentadienoic acid was slowly added at a constant temperature of 30±5°C for 2-3 hours. The reaction was continued for 18-24 hours. The mixture was then distilled under reduced pressure at 50±5°C and 133 Pa to obtain a light yellow oily liquid. S2: Add thiourea acetic acid solution to the light yellow oily liquid, heat to 40-60°C, stir and react for 3-5 hours, cool to room temperature, precipitate solid, filter, wash with water, and vacuum dry to obtain.

3. A closed circulating water system soft water corrosion inhibitor according to claim 2, characterized in that: The mass ratio of the methanol to the triethylenetetramine is 4:1, and the molar ratio of the triethylenetetramine to 2,4-pentadienoic acid is 1:(7-8).

4. A closed circulating water system soft water corrosion inhibitor according to claim 2, characterized in that: The molar ratio of thiourea to triethylenetetramine is (6-7):

1.

5. A closed circulating water system soft water corrosion inhibitor according to claim 1, characterized in that: The effective content of the borax is ≥90.0 wt%.

6. A method for preparing a soft water corrosion inhibitor for a closed circulating water system according to claim 5, characterized in that: The following steps are involved: S1: Weigh the macromolecular amino acid compound, zinc chloride, borax, and deionized water according to the ratio; S2: Add the weighed deionized water, macromolecular amino acid compound, zinc chloride and borax into a stirring tank in sequence, stir at 40-50° C. for 30-60 minutes, and filter to obtain a closed circulating water system soft water corrosion inhibitor.

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