A method for treating and reusing cooling water

Abstract

The present invention relates to the technical field of industrial cooling water treatment, and specifically discloses a method for reusing cooling water treatment. Compared with existing scale inhibitors, the composite scale inhibitor provided by the present invention has the characteristics of high efficiency and environmental protection. No phosphorus-containing substances are used in its components, so it will not cause secondary damage to water quality. Moreover, under the synergistic effect of multiple components, it can disperse scale-forming particles such as high-concentration calcium ions and magnesium ions with very little usage amount, and has excellent scale inhibition effect; the composite copolymer provided by the present invention can form a very strong coordination effect with the surface of steel. During the corrosion process, the carboxymethyl chitosan and the double-bond addition reaction product can form a dense and stable polymer film on the surface of the steel. Under the combined action of the two, it hinders the direct contact between the corrosive medium and the surface of the steel and causes corrosion, protects the metal from corrosion by harmful media, and has a good corrosion inhibition effect.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial cooling water treatment, and particularly relates to a method for reusing cooled water treatment. Background Art

[0002] During the recycling process of industrial cooling water, many problems are often faced, such as inorganic salt deposition, metal corrosion, and the growth of bacteria and algae microorganisms, which seriously affect the normal operation efficiency of the system. Over time, due to the accumulation of inorganic salts dissolved in water, such as calcium carbonate, calcium sulfate, and barium sulfate, these substances will gradually deposit on the inner surface of the pipeline, forming thick calcium scale. The formation of this calcium scale will hinder the flow of cooling water, resulting in a significant reduction in the heat transfer efficiency of the heat exchange equipment, and may further cause insufficient heat exchange capacity of the entire cooling system. In addition, the attachment of calcium scale not only reduces the surface area of heat exchange, but may also cause pipeline blockage, increasing the difficulty and cost of system maintenance, and even causing equipment damage and production stoppage in severe cases.

[0003] During the operation of circulating cooling water, adding corrosion and scale inhibitors is one of the important methods to stabilize water quality, inhibit corrosion and scale. Currently, most commonly used corrosion and scale inhibitors are phosphorus-containing formulations. Since phosphorus is one of the main causes of water eutrophication, the state strictly controls the total phosphorus index in the external drainage of enterprises. Phosphorus-free and low-phosphorus corrosion and scale inhibitors have become a new direction for the research and development of water treatment agents.

[0004] Chinese Patent Document CN102838215A discloses a composite scale inhibitor composed of polyepoxysuccinic acid, ethylenediamine tetra (methylenephosphonic acid), itaconic acid-maleic acid-acrylic acid-methyl acrylate polymer, and dendritic polyamide-amine; the weight percentages of the components of the scale inhibitor are: polyepoxysuccinic acid 22-32%, ethylenediamine tetra (methylenephosphonic acid) 10-18%, itaconic acid-maleic acid-acrylic acid-methyl acrylate polymer 35-50%, dendritic polyamide-amine 10-18%, and the rest is water. Practice has proved that these traditional organic phosphonate scale inhibitors and anionic polymer scale dispersants cannot simultaneously achieve good scale inhibition effects on amorphous SiO2 scale precipitation, calcium carbonate scale, calcium sulfate scale, etc. However, the above composite scale inhibitor contains phosphorus and is not environmentally friendly. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method for reusing cooled water treatment. The composite scale inhibitor provided by the present invention does not contain phosphorus and has excellent scale inhibition performance and corrosion inhibition performance.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] A method for reusing cooling water treatment, the method includes adding a composite scale inhibitor to the cooling water. Calculated by mass percentage, the composite scale inhibitor includes raw materials of the following components: 10-15% of composite copolymer, 5-10% of octylphenol polyoxyethylene ether, 3-6% of glycerol, 2-4% of tetrasodium ethylenediaminetetraacetate, 1-3% of zinc salt, and the rest is deionized water;

[0008] The preparation method of the composite copolymer is as follows:

[0009] Add carboxymethyl chitosan, 1-vinyl-3-methylimidazolium p-toluenesulfonate and methacryloylethyl sulfobetaine to deionized water, stir evenly, pass nitrogen to discharge air, heat the system to 65-75 °C, then add an initiator, stir and react. After the reaction is completed, cool to room temperature and perform vacuum freeze-drying to obtain the composite copolymer.

[0010] Based on the above technical solution, specifically, the addition amount of the composite scale inhibitor is 10-40 mg / L. For example, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L, 35 mg / L, 40 mg / L can be selected, but it is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0011] Based on the above technical solution, specifically, the mass ratio of carboxymethyl chitosan, 1-vinyl-3-methylimidazolium p-toluenesulfonate, methacryloylethyl sulfobetaine and the initiator is 10-20:4-8:3-6:0.5-1.

[0012] More specifically, the initiator is selected from persulfates. For example, potassium persulfate, sodium persulfate or ammonium persulfate can be selected.

[0013] Based on the above technical solution, specifically, the temperature of the stirring reaction is 65-75 °C. For example, 65 °C, 68 °C, 70 °C, 72 °C, 75 °C can be selected; the time of the stirring reaction is 2-4 h. For example, 2 h, 2.5 h, 3 h, 3.5 h, 4 h can be selected, but it is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0014] Based on the above technical solution, specifically, the zinc salt is selected from zinc nitrate or zinc chloride.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) Compared with existing scale inhibitors, the composite scale inhibitor provided by the present invention has the characteristics of high efficiency and environmental protection. None of the components adopt any phosphorus-containing substances, which will not cause secondary damage to water quality. Moreover, under the synergistic effect of multiple components, it can disperse scale-forming particles such as high-concentration calcium ions, magnesium ions, iron ions, and sulfate radicals with very little usage amount, and has excellent scale inhibition effect.

[0017] (2) In the present invention, 1-vinyl-3-methylimidazolium p-toluenesulfonate and methacryloylethyl sulfobetaine are subjected to a double-bond addition reaction to form a polymer. During the addition reaction, the hydroxyl groups in carboxymethyl chitosan and the carboxyl groups and sulfonic acid groups in the polymer act through hydrogen bonds and other interactions, and carboxymethyl chitosan is embedded in the molecular chain of the polymer, thereby obtaining a composite copolymer; the carboxyl groups, hydroxyl groups, and sulfonic acid groups in the composite copolymer can undergo coordination chelation with calcium ions, enabling the composite copolymer to adsorb on the surfaces of calcium carbonate and calcium phosphate crystals, inhibiting the crystallization of calcium carbonate and calcium phosphate to form crystal scale, slowing down the crystal growth rate, increasing the repulsion between crystals, preventing them from aggregating, and thus making the generated dirt soft and easily carried away by the scouring of water flow, achieving a good scale inhibition effect.

[0018] (3) The composite copolymer provided by the present invention can form a very strong coordination effect with the steel surface. During the corrosion process, carboxymethyl chitosan and the product of the double-bond addition reaction can form a dense and stable polymer film on the steel surface. Under the combined action of the two, it hinders the direct contact between the corrosive medium and the steel surface to cause corrosion, protects the metal from the corrosion of harmful media, and further slows down the corrosion rate of the metal, achieving a good corrosion inhibition effect; at the same time, the composite copolymer contains carboxymethyl chitosan, imidazole groups, and benzene ring structures, and has strong thermal stability, can adapt to high-temperature and high-salinity environments, and meets the requirements of on-site production. Specific Embodiments

[0019] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0020] It should be noted that unless otherwise specified, the chemical reagents involved in the present invention are all purchased through commercial channels.

[0021] In the embodiments of the present invention, the octylphenol polyoxyethylene ether used has the model of OP-10 and is purchased from Yixing Jiayuan Chemical Co., Ltd.; the CAS number of carboxymethyl chitosan is 83512-85-0 and is purchased from Wuhan Lana White Pharmaceutical and Chemical Co., Ltd.; the CAS number of 1-vinyl-3-methylimidazolium p-toluenesulfonate is 187387-86-6; the CAS number of methacryloylethyl sulfobetaine is 3637-26-1 and is purchased from Shanghai Yuanye Bio-Technology Co., Ltd.

[0022] Example 1

[0023] This example is used to illustrate the method for reusing cooling water treatment provided by the present invention.

[0024] The cooling water used in this example is simulated industrial cooling water, with pH = 8.3, conductivity 946.9 μS / cm, total hardness (calcium carbonate) 74.68 mg / L, calcium hardness 36.27 mg / L, total alkalinity 58.4 mg / L, chloride ion 76.82 mg / L, and sulfate radical 56.64 mg / L.

[0025] A composite scale inhibitor is added to the cooling water. The dosage of the composite scale inhibitor is 10 mg / L. By mass percentage, the composite scale inhibitor includes the following raw materials: 10% of composite copolymer, 10% of octylphenol polyoxyethylene ether, 5% of glycerol, 3% of tetrasodium ethylenediaminetetraacetate, 2% of zinc chloride, and the rest is deionized water.

[0026] Among them, the preparation method of the composite copolymer is as follows:

[0027] Add 10 g of carboxymethyl chitosan, 4 g of 1-vinyl-3-methylimidazolium p-toluenesulfonate, and 3 g of methacryloylethyl sulfobetaine to 100 mL of deionized water, stir evenly, pass nitrogen to expel air, heat the system to 70 °C, then add 0.5 g of initiator ammonium persulfate, stir and react at 70 °C for 3 h. After the reaction is completed, cool to room temperature and perform vacuum freeze-drying to obtain the composite copolymer.

[0028] Example 2

[0029] This example is used to illustrate the method for reusing cooling water treatment provided by the present invention.

[0030] The cooling water used in this example is simulated industrial cooling water, with pH = 8.3, conductivity 946.9 μS / cm, total hardness (calcium carbonate) 74.68 mg / L, calcium hardness 36.27 mg / L, total alkalinity 58.4 mg / L, chloride ion 76.82 mg / L, and sulfate radical 56.64 mg / L.

[0031] A composite scale inhibitor is added to the cooling water. The dosage of the composite scale inhibitor is 20 mg / L. By mass percentage, the composite scale inhibitor includes the following raw materials: 15% of composite copolymer, 8% of octylphenol polyoxyethylene ether, 6% of glycerol, 4% of tetrasodium ethylenediaminetetraacetate, 3% of zinc chloride, and the rest is deionized water.

[0032] Among them, the preparation method of the composite copolymer is as follows:

[0033] 20 g of carboxymethyl chitosan, 8 g of 1-vinyl-3-methylimidazolium p-toluenesulfonate and 6 g of methacryloylethyl sulfobetaine were added to 150 mL of deionized water, stirred evenly, purged with nitrogen to remove air, the system was heated to 70 °C, then 1 g of initiator ammonium persulfate was added, and stirred at 70 °C for 3 h. After the reaction was completed, it was cooled to room temperature and freeze-dried under vacuum to obtain the composite copolymer.

[0034] Example 3

[0035] This example is used to illustrate the method for reusing cooling water treatment provided by the present invention.

[0036] The cooling water used in this example is simulated industrial cooling water, with pH = 8.3, conductivity 946.9 μS / cm, total hardness (calcium carbonate) 74.68 mg / L, calcium hardness 36.27 mg / L, total alkalinity 58.4 mg / L, chloride ion 76.82 mg / L, and sulfate radical 56.64 mg / L.

[0037] A composite scale inhibitor was added to the cooling water. The dosage of the composite scale inhibitor was 30 mg / L. By mass percentage, the composite scale inhibitor included the following raw materials: 15% of composite copolymer, 8% of octylphenol polyoxyethylene ether, 6% of glycerol, 4% of tetrasodium ethylenediaminetetraacetate, 3% of zinc chloride, and the rest was deionized water.

[0038] Among them, the preparation method of the composite copolymer is as follows:

[0039] 15 g of carboxymethyl chitosan, 6 g of 1-vinyl-3-methylimidazolium p-toluenesulfonate and 5 g of methacryloylethyl sulfobetaine were added to 150 mL of deionized water, stirred evenly, purged with nitrogen to remove air, the system was heated to 70 °C, then 0.8 g of initiator ammonium persulfate was added, and stirred at 70 °C for 3 h. After the reaction was completed, it was cooled to room temperature and freeze-dried under vacuum to obtain the composite copolymer.

[0040] Example 4

[0041] This example is used to illustrate the method for reusing cooling water treatment provided by the present invention.

[0042] The cooling water used in this example is simulated industrial cooling water, with pH = 8.3, conductivity 946.9 μS / cm, total hardness (calcium carbonate) 74.68 mg / L, calcium hardness 36.27 mg / L, total alkalinity 58.4 mg / L, chloride ion 76.82 mg / L, and sulfate radical 56.64 mg / L.

[0043] Add a composite scale inhibitor to the cooling water. The dosage of the composite scale inhibitor is 40 mg / L. By mass percentage, the composite scale inhibitor comprises the following raw materials: 12% of a composite copolymer, 8% of octylphenol polyoxyethylene ether, 3% of glycerol, 2% of tetrasodium ethylenediaminetetraacetate, 1% of zinc chloride, and the balance is deionized water.

[0044] Among them, the preparation method of the composite copolymer is as follows:

[0045] Add 15 g of carboxymethyl chitosan, 6 g of 1-vinyl-3-methylimidazolium p-toluenesulfonate, and 5 g of methacryloylethyl sulfobetaine to 150 mL of deionized water, stir evenly, pass nitrogen to remove air, heat the system to 70 °C, then add 0.8 g of initiator ammonium persulfate, stir and react at 70 °C for 3 h. After the reaction is completed, cool to room temperature and conduct vacuum freeze-drying to obtain the composite copolymer.

[0046] Comparative Example 1

[0047] This comparative example is used to illustrate the method for reusing treated cooling water provided by the present invention.

[0048] The cooling water used in this comparative example is simulated industrial cooling water, with pH = 8.3, conductivity 946.9 μS / cm, total hardness (calcium carbonate) 74.68 mg / L, calcium hardness 36.27 mg / L, total alkalinity 58.4 mg / L, chloride ion 76.82 mg / L, and sulfate radical 56.64 mg / L.

[0049] Add a composite scale inhibitor to the cooling water. The dosage of the composite scale inhibitor is 30 mg / L. By mass percentage, the composite scale inhibitor comprises the following raw materials: 15% of carboxymethyl chitosan, 8% of octylphenol polyoxyethylene ether, 6% of glycerol, 4% of tetrasodium ethylenediaminetetraacetate, 3% of zinc chloride, and the balance is deionized water.

[0050] Compared with Example 3, in Comparative Example 1, carboxymethyl chitosan is used to replace the composite copolymer.

[0051] Comparative Example 2

[0052] This comparative example is used to illustrate the method for reusing treated cooling water provided by the present invention.

[0053] The cooling water used in this comparative example is simulated industrial cooling water, with pH = 8.3, conductivity 946.9 μS / cm, total hardness (calcium carbonate) 74.68 mg / L, calcium hardness 36.27 mg / L, total alkalinity 58.4 mg / L, chloride ion 76.82 mg / L, and sulfate radical 56.64 mg / L.

[0054] Add a composite scale inhibitor to the cooling water. The dosage of the composite scale inhibitor is 30 mg / L. Calculated by mass percentage, the composite scale inhibitor includes raw materials of the following components: 15% of a composite copolymer, 8% of octylphenol polyoxyethylene ether, 6% of glycerol, 4% of tetrasodium ethylenediaminetetraacetate, 3% of zinc chloride, and the balance is deionized water.

[0055] Among them, the preparation method of the composite copolymer is as follows:

[0056] Add 6 g of 1-vinyl-3-methylimidazole p-toluenesulfonate and 5 g of methacryloylethyl sulfobetaine to 150 mL of deionized water, stir evenly, pass nitrogen to discharge air, heat the system to 70 °C, then add 0.8 g of initiator ammonium persulfate, stir and react at 70 °C for 3 h. After the reaction is completed, cool to room temperature and perform vacuum freeze-drying to obtain the composite copolymer.

[0057] Compared with Example 3, carboxymethyl chitosan was not added to the composite copolymer in Comparative Example 2.

[0058] Calcium carbonate scale inhibition test: The test is carried out with reference to the standard of GB / T 16632-2019 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Carbonate Deposition Method";

[0059] Calcium phosphate scale inhibition test: The test is carried out with reference to the standard of GB / T 22626-2008 "Determination of Scale Inhibition Performance of Water Treatment Agents - Calcium Phosphate Deposition Method";

[0060] The test results are shown in Table 1.

[0061] Table 1 Test Results of Scale Inhibition Performance

[0062]

[0063]

[0064] Corrosion inhibition performance test: It is carried out according to the standard of GB / T18175-2014. The coupon material is Q245R, the test temperature is 80 °C, the test time is 72 h, and the stirring linear velocity is 0.33 m / s. The test results are shown in Table 2.

[0065] Table 2 Test Results of Corrosion Inhibition Performance

[0066] Corrosion rate (mm / a) Example 1 0.021 Example 2 0.019 Example 3 0.014 Example 4 0.013 Comparative Example 1 0.072 Comparative Example 2 0.047

[0067] As can be seen from Table 2, in Comparative Example 1, carboxymethyl chitosan was used to replace the composite copolymer, and carboxymethyl chitosan was not added to the composite copolymer in Comparative Example 2. At the same time, the addition amount of the composite copolymer remained unchanged. The corrosion inhibition effects of Comparative Example 1 and Comparative Example 2 were both inferior to those of the examples of the present invention. It can be seen that there is a synergistic effect among the components of the composite copolymer provided by the present invention, which jointly plays a good corrosion inhibition effect.

[0068] Finally, it should be noted that the above embodiments do not limit the present invention in any form. For those skilled in the art, based on the present invention, some modifications and improvements can be made. Therefore, any modification or improvement made without departing from the spirit of the present invention falls within the scope of protection of the present invention.

Claims

1. A method for reusing cooling water treatment, characterized in that, The method includes adding a composite scale inhibitor to the cooling water. In terms of mass percentage content, the composite scale inhibitor comprises raw materials of the following components: 10-15% of a composite copolymer, 5-10% of octylphenol polyoxyethylene ether, 3-6% of glycerol, 2-4% of tetrasodium ethylenediaminetetraacetate, 1-3% of zinc salt, and the balance being deionized water; The preparation method of the composite copolymer is as follows: Carboxymethyl chitosan, 1-vinyl-3-methylimidazolium p-toluenesulfonate and methacryloylethyl sulfobetaine are added to deionized water, stirred evenly, nitrogen is introduced to discharge air, the system is heated to 65-75 °C, then an initiator is added, and stirring reaction is carried out. After the reaction is completed, it is cooled to room temperature and vacuum freeze-dried to obtain the composite copolymer; Among them, the mass ratio of carboxymethyl chitosan, 1-vinyl-3-methylimidazolium p-toluenesulfonate, methacryloylethyl sulfobetaine and the initiator is 10-20:4-8:3-6:0.5-1.

2. The method according to claim 1, wherein The addition amount of the composite scale inhibitor is 10-40 mg / L.

3. The method according to claim 1, wherein The initiator is selected from persulfates.

4. The method according to claim 3, characterized in that The persulfate is selected from potassium persulfate, sodium persulfate or ammonium persulfate.

5. The method according to claim 1, wherein The temperature of the stirring reaction is 65-75 °C, and the time of the stirring reaction is 2-4 h.

6. The method according to claim 1, wherein The zinc salt is selected from zinc nitrate or zinc chloride.

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