Circulating water treatment method, corrosion and scale inhibitor and application of corrosion and scale inhibitor

Abstract

The invention relates to the field of corrosion and scale inhibition of circulating water, and discloses a circulating water treatment method, a corrosion and scale inhibitor containing a compound as shown in a formula I and application of the corrosion and scale inhibitor. Compared with traditional corrosion and scale inhibition commonly used for circulating water systems, the compound shown in the formula I has better corrosion and scale inhibition performance, and the corrosion and scale inhibition method can greatly slow down the corrosion speed of water pumps, pipelines, heat exchangers and other metal equipment in the circulating water systems; and scale in a circulating water system can be efficiently prevented, and the service life of equipment is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of corrosion and scale inhibition in circulating water, and specifically, to a method for treating circulating water, a corrosion and scale inhibitor, and their applications. Background Art

[0002] At present, etidronic acid or 2-hydroxyphosphonoacetic acid is often added to circulating cooling water. The added etidronic acid can be used as a corrosion and scale inhibitor, which can take into account both corrosion inhibition and scale inhibition effects in circulating cooling water, but its corrosion and scale inhibition effects are poor. While 2-hydroxyphosphonoacetic acid can only act as a corrosion inhibitor in circulating cooling water, with only corrosion inhibition effect and little scale inhibition effect. Therefore, it is of great significance to develop a corrosion and scale inhibitor with better effects. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above problems existing in the prior art, and to provide a method for treating circulating water, a corrosion and scale inhibitor, and their applications.

[0004] To achieve the above purpose, in the first aspect of the present invention, a method for treating circulating water is provided, which includes adding a corrosion and scale inhibitor to the circulating water. It is characterized in that the corrosion and scale inhibitor contains a compound shown in Formula I:

[0005] In the second aspect of the present invention, a corrosion and scale inhibitor is provided, which is characterized in that the composition of the corrosion and scale inhibitor is the same as that of the above corrosion and scale inhibitor.

[0006] In the third aspect of the present invention, an application of the compound shown in Formula I in reducing the corrosion rate of metal equipment in a circulating water system is provided.

[0007] In the fourth aspect of the present invention, an application of the compound shown in Formula I in preventing scale formation in a circulating water system is provided.

[0008] Through the above technical solutions, the present invention can at least obtain the following beneficial effects: Compared with the traditional corrosion and scale inhibitors commonly used in circulating water systems, the compound shown in Formula I can simultaneously achieve scale inhibition and corrosion inhibition effects, and has excellent corrosion and scale inhibition performance. Using the corrosion and scale inhibition method of the present invention can greatly reduce the corrosion rate of metal equipment such as water pumps, pipelines, and heat exchangers in the circulating water system, and can also efficiently prevent the formation of scale in the circulating water system, improving the service life of the equipment. Detailed Embodiments

[0009] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0010] In the first aspect of the present invention, there is provided a method for treating circulating water, the method comprising adding a corrosion and scale inhibitor to the circulating water, characterized in that the corrosion and scale inhibitor contains a compound having a structure as shown in formula I:

[0011] In the present invention, the treatment temperature can be 40 - 90 °C, preferably 50 - 80 °C.

[0012] In the present invention, the circulating water can be the common industrial circulating water in the art, and there are no particular limitations on its type and content. In particular, the circulating water contains 50 - 500 mg / L of Ca 2+ , 10 - 500 mg / L of HCO3 - , less than 550 mg / L of Cl - and less than 400 mg / L of SO4 2- . Preferably, the circulating water contains 80 - 250 mg / L of Ca 2+ , 70 - 500 mg / L of HCO3 - , 20 - 500 mg / L of Cl - and 20 - 70 mg / L of SO4 2- .

[0013] In the present invention, the dosage of the compound shown in formula I is not particularly limited, as long as it can achieve the effect of corrosion and scale inhibition on the circulating water equipment. Preferably, the dosage of the compound shown in formula I is such that the concentration of the compound shown in formula I in the circulating water can be 0.01 - 5 mmol / L; preferably 0.05 - 3.5 mmol / L.

[0014] In the second aspect of the present invention, there is provided a corrosion and scale inhibitor, characterized in that the corrosion and scale inhibitor contains a compound having a structure as shown in formula I. The corrosion and scale inhibitor may further contain other agents common in the art having corrosion inhibition and / or scale inhibition properties. In the corrosion and scale inhibitor, the content of the compound shown in formula I is ≥ 10% by weight, preferably ≥ 30% by weight, preferably ≥ 50% by weight, preferably ≥ 70% by weight, preferably ≥ 90% by weight.

[0015] In the third aspect of the present invention, there is provided the use of the compound represented by Formula I in slowing down the corrosion rate of metal equipment in a circulating water system.

[0016] In the present invention, the dosage of the compound represented by Formula I is such that the concentration of the compound represented by Formula I in the circulating water can be 0.01 - 2 mmol / L, preferably 0.01 - 0.5 mmol / L, more preferably 0.03 - 0.25 mmol / L, still more preferably 0.05 - 0.2 mmol / L, and most preferably 0.1 - 0.15 mmol / L. When the compound represented by Formula I adopts the concentration within the most preferred range, the corrosion inhibition rate for metals in the circulating water system is as high as over 99% (in terms of molar concentration).

[0017] In the fourth aspect of the present invention, there is provided the use of the compound represented by Formula I in preventing scale formation in a circulating water system.

[0018] In the present invention, the dosage of the compound represented by Formula I is such that the concentration of the compound represented by Formula I in the circulating water can be 0.2 - 5 mmol / L, preferably 1.5 - 4 mmol / L, more preferably 2 - 3.5 mmol / L, and most preferably 2.8 - 3.2 mmol / L. When the compound represented by Formula I adopts the concentration within the most preferred range, the scale inhibition rate in the circulating water system is as high as over 99% (in terms of molar concentration).

[0019] The present invention will be described in detail below through examples.

[0020] In the following examples and comparative examples,

[0021] HDPA (the structure is as shown) was purchased from Bide Pharmaceutical Co., Ltd., and the CAS number is 90966 - 62 - 4.

[0022] Etidronic acid (HEDP) was purchased from Jiangsu Jianghai Chemical Co., Ltd., and the CAS number is 2809 - 21 - 4.

[0023] 2 - Hydroxyphosphonoacetic acid (HPAA) was purchased from Jiangsu Qiangsheng Chemical Co., Ltd., and the CAS number is 23783 - 26 - 8.

[0024] The experimental instrument for the rotating coupon test was a ZJ - type immersion corrosion tester, and the test coupon was a carbon steel coupon.

[0025] Example 1

[0026] Static scale inhibition experiment:

[0027] (1) Preparation of simulated circulating water: Add 0.88 g of calcium chloride dihydrate granules into a beaker containing 1000 ml of water, stir until completely dissolved; then add 0.67 g of sodium bicarbonate powder and stir until completely dissolved to obtain simulated circulating water;

[0028] (2) Pour 500 ml of the simulated circulating water into a 1000 ml volumetric flask, and add HDPA with concentrations of 0.5, 1, 1.5, 2, 2.5, 3, and 3.5 mmol / L respectively to prepare test waters containing different concentrations of the agent;

[0029] (3) Place the volumetric flask containing the test water in step (2) into a water bath at 80 °C, keep the water bath at a constant temperature for 10 h, then take out the volumetric flask, cool it to room temperature, filter, and pipette 100 ml of the filtrate into a volumetric flask, add an appropriate amount of distilled water, and use the EDTA standard solution complexometric titration method to determine the Ca 2+ content, and then obtain the scale inhibition rate as shown in Table 1 according to the measurement results and the scale inhibition rate η calculation formula.

[0030] The calculation formula for the scale inhibition rate η is: In the formula:

[0031] represents the calcium ion concentration in the test solution after adding the water treatment agent, mmol / L;

[0032] represents the calcium ion concentration in the blank test solution without adding the water treatment agent after the experiment, mmol / L;

[0033] represents the calcium ion concentration in the prepared water before the experiment, mmol / L.

[0034] Example 2

[0035] Rotating coupon experiment:

[0036] (1) Preparation of test water: Add 0.1 g of sodium chloride, 0.1 g of sodium bicarbonate, and 0.1 g of sodium sulfate into a beaker containing 1000 ml of water in sequence, stir until completely dissolved to obtain simulated circulating water, then take 500 ml of the simulated circulating water into a volumetric flask, and add 0.05, 0.1, 0.15, 0.2, and 0.25 mmol / L of HDPA to it respectively, stir until uniform, and prepare test waters containing different concentrations of the agent for standby.

[0037] (2) Pretreatment of the test coupon: Before immersing the standard test coupon in the aqueous solution, check that there are no obvious scratches, cracks, and spots on the surface of the test coupon. Measure its size precisely with a vernier caliper, then scrub it with detergent, rinse it with water, and then scrub it with anhydrous ethanol. Remove the surface grease, dry it with a hair dryer, place the test coupon in a desiccator, after cooling to room temperature, weigh it with an analytical balance, and record the coupon weight m0.

[0038] (3) Normal operation: Fix the test piece on the rotary coupon apparatus, immerse it in the test water and rotate it, control the rotation speed of the test piece in the water to be 0.5 ± 0.05 m / s, heat the water bath to 50 °C and conduct a 72-hour corrosion test.

[0039] (4) Post-treatment of the test piece: After taking out the corroded test piece, place it in the inhibited hydrochloric acid solution, carefully scrub the corrosion products with a cotton ball until the metal is exposed, then rinse with water, neutralize with 0.2 mol / L NaOH solution, rinse with water again, then scrub with ethanol, dry with a hair dryer, place it in a desiccator and cool to room temperature, weigh it with an analytical balance, and record the coupon weight m.

[0040] The corrosion inhibition performance is expressed by the corrosion inhibition rate ω, and the calculation formula is: b is the corrosion rate, and the calculation formula is: In the formula,

[0041] m is the mass of the test piece after the test, g;

[0042] m0 is the mass of the test piece before the test, g;

[0043] A is the surface area of the test piece, m 2 ;

[0044] T is the time for which the test piece is corroded, 72 h;

[0045] b0 is the corrosion rate of the test piece in the blank test without adding water treatment agent, g / (m 2 h);

[0046] b is the corrosion rate of the test piece in the test with water treatment agent added, g / (m 2 h).

[0047] According to the calculation formulas of the corrosion rate b and the corrosion inhibition rate ω, the corrosion inhibition rate is shown in Table 2.

[0048] Comparative Example 1

[0049] Treat the simulated circulating water according to the method of Example 1, except that HDPA is replaced with HEDP. According to the measurement results and the calculation formula of the scale inhibition rate η, the scale inhibition rate is shown in Table 1.

[0050] Comparative Example 2

[0051] Treat the simulated circulating water according to the method of Example 2, except that HDPA is replaced with HEDP. According to the calculation formulas of the corrosion rate b and the corrosion inhibition rate ω, the corrosion inhibition rate is shown in Table 2.

[0052] Comparative Example 3

[0053] The simulated circulating water was treated according to the method of Example 1, except that HDPA was replaced with HPAA. The scale inhibition rate was obtained according to the measurement results and the calculation formula of the scale inhibition rate η, as shown in Table 1.

[0054] Comparative Example 4

[0055] The simulated circulating water was treated according to the method of Example 2, except that HDPA was replaced with HPAA. The corrosion inhibition rate was obtained according to the calculation formulas of the corrosion rate b and the corrosion inhibition rate ω, as shown in Table 2.

[0056] Table 1 Scale inhibition rates at different concentrations (in molar concentration, %)

[0057] Example 1 Comparative Example 1 Comparative Example 3 Concentration (mmol / L) HDPA HEDP HPAA 0.5 49.31 32.46 0.00 1 66.90 61.42 0.00 1.5 80.73 74.80 0.00 2 90.81 81.41 1.01 2.5 97.15 85.08 3.71 3 99.73 87.30 6.84 3.5 98.57 88.74 10.30

[0058] Table 2 Corrosion inhibition rates at different concentrations (in molar concentration, %)

[0059] Example 2 Comparative Example 2 Comparative Example 4 Concentration (mmol / L) HDPA HEDP HPAA 0.05 94.58 61.43 52.87 0.1 99.60 78.28 85.77 0.15 99.65 85.35 95.22 0.2 94.71 85.94 98.09 0.25 84.78 76.30 98.76

[0060] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for treating circulating water, the method comprising adding an inhibitor and scale inhibitor to the circulating water, characterized in that, The corrosion and scale inhibitor contains a compound with a structure shown in Formula I:

2. The method according to claim 1, wherein, The treatment temperature is 20 - 90 °C, preferably 50 - 80 °C.

3. The method according to claim 1 or 2, wherein The circulating water contains 50 - 500 mg / L of Ca 2+ , 10 - 500 mg / L of HCO3 - , less than 550 mg / L of Cl - and less than 400 mg / L of SO4 2- .

4. The method according to any one of claims 1 to 3, wherein The circulating water contains 80 - 250 mg / L of Ca 2+ , 70 - 500 mg / L of HCO3 - , 20 - 500 mg / L of Cl - and 20 - 70 mg / L of SO4 2- .

5. The method according to any one of claims 1-4, wherein, The dosage of the compound shown in Formula I is such that the concentration of the compound shown in Formula I in the circulating water is 0.01 - 5 mmol / L; preferably 0.05 - 3.5 mmol / L.

6. An anti-corrosion and scale inhibitor, characterized in that, This corrosion and scale inhibitor contains a compound with a structure shown in Formula I.

7. Use of the compound shown in Formula I or the corrosion and scale inhibitor according to Claim 6 in reducing the corrosion rate of metal equipment in a circulating water system.

8. The application according to claim 7, wherein, The dosage of the compound shown in Formula I is such that the concentration of the compound shown in Formula I in the circulating water is 0.01 - 0.5 mmol / L, preferably 0.03 - 0.25 mmol / L, more preferably 0.05 - 0.2 mmol / L, and most preferably 0.1 - 0.15 mmol / L.

9. Use of the compound shown in Formula I or the corrosion and scale inhibitor according to Claim 6 in preventing scale formation in a circulating water system.

10. The application according to claim 9, wherein The dosage of the compound shown in Formula I is such that the concentration of the compound shown in Formula I in the circulating water is 0.2 - 5 mmol / L; preferably 1.5 - 4 mmol / L, more preferably 2 - 3.5 mmol / L, and most preferably 2.8 - 3.2 mmol / L.

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