Special scale and corrosion inhibitor for circulating water system based on electrochemical descaling and preparation method thereof

Abstract

The invention discloses a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling and a preparation method thereof. The scale inhibitor and corrosion inhibitor of the invention comprises a scale inhibitor component, acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer, which is heated to 86-92°C under stirring conditions through raw materials acrylic acid and methyl acrylate, and then ammonium persulfate is added dropwise, and the temperature is maintained for constant temperature reaction to obtain an acrylic acid-methyl acrylate solution, and then aminoethanesulfonic acid is added to completely dissolve, and finally concentrated sulfuric acid is added, and the temperature is kept to continue the reaction. The scale inhibitor and corrosion inhibitor obtained by compounding the terpolymer with other scale inhibitors and corrosion inhibitor components is particularly suitable for a circulating water system with an electrochemical descaling device, has strong anti-electrolysis ability, significantly reduces the influence on the electrochemical descaling effect, and has good scale inhibitor and corrosion inhibitor compatibility, so that the electrochemical descaling technology and the scale inhibitor and corrosion inhibitor can be well matched, stabilize the water quality of the circulating water, and achieve true zero discharge of circulating water on the basis of safe operation and effective control of operating costs.

Description

Technical Field

[0001] The invention relates to the technical field of scale inhibitors and corrosion inhibitors, in particular to a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling, and a preparation method of the scale inhibitor and corrosion inhibitor. Background Art

[0002] Industrial circulating cooling water (also called industrial circulating water) is an indispensable heat exchange medium in the production fields of metallurgy, energy, chemical industry, etc. The three major problems that the circulating water system must face and solve during operation are system scaling, system corrosion and microbial contamination. At present, chemical treatment is generally used, that is, adding chemical agents to the circulating water to treat the circulating water to keep the water quality stable, so as to reduce the adverse effects of the increase in the concentration of scaling ions, corrosive ions and microorganisms in the water due to the concentration of circulating water on pipelines and equipment.

[0003] The chemical treatment method uses chemical agents to adjust the dissolution-precipitation balance of scaling and corrosive ions in water. Since the ion content will not be changed, forced sewage discharge is required after the circulating water is concentrated to a certain multiple. Usually, for the operation of high-hardness and high-salinity circulating water, only a lower concentration multiple can be controlled, so the enterprise's sewage discharge is large and more water resources are consumed; in addition, due to the large variety of chemical agents added to the circulating water, the difficulty and cost of the reclaimed water treatment process will be greatly increased.

[0004] The electrochemical treatment method uses the oxygen evolution reaction at the anode during the electrolysis process to produce H + , the cathode undergoes hydrogen evolution reaction to produce OH-, and when water flows near the cathode plate, the scaling ions are scaled and precipitated on the cathode plate, which plays a role in descaling. The application of electrochemical descaling began in the 1940s, but at that time, due to large investments and high costs, it developed slowly; with the continuous improvement of electrochemical technology and equipment, the further optimization of electrolysis efficiency and energy consumption levels, the benefits of electrochemical treatment methods to reduce the hardness of circulating water to increase the concentration multiple have been reflected, and have been gradually promoted in the circulating water market. Since electrolysis is descaling rather than scale inhibition, it will not change the scaling and corrosion tendency of water, so the electrochemical treatment method has no corrosion inhibition effect on metals. On the contrary, the addition of the electric field also increases the corrosion rate of steel in water. Therefore, it is impossible to completely solve the scaling, corrosion and microbial problems of circulating water by only using electrochemical treatment methods.

[0005] With the increasing scarcity of water resources and the significant increase in water costs, enterprises have tried to use electrochemical equipment to remove scale-forming ions in circulating water and combine it with chemical agents to treat circulating water in order to save water as much as possible, so as to give full play to the advantages of electrolysis technology in reducing the hardness of circulating water and solve the corrosion problem at the same time. However, as the system is running, it is found that due to the scale inhibition mechanism of chemical agents (that is, after adding scale and corrosion inhibitors, under the action of complexation and solubilization, the scale and corrosion inhibition components can react with Ca in water 2+ Mg2+ The metal ions form stable complexes, which increase the CaCO 3 Solubility in water; on the other hand, under the action of lattice distortion and electrostatic repulsion, a soft scale layer is formed, which is suspended in the water in a dispersed state and is not easy to deposit and adhere) and the contradiction between the electrochemical descaling mechanism (i.e., extracting and precipitating scale ions from water), resulting in electrochemical equipment with reduced electrolysis efficiency and increased electrolysis energy consumption due to the addition of scale inhibitors and corrosion inhibitors. In addition, electrolytic treatment promotes the decomposition of scale inhibitors and corrosion inhibitors. During operation, when the concentration of circulating water increases and the residence time of scale inhibitors and corrosion inhibitors in the system increases significantly, the decomposition of scale inhibitors and corrosion inhibitors is aggravated, resulting in a significant decrease in agent concentration and serious bacterial growth in the circulating water system. Therefore, the development of scale inhibitors and corrosion inhibitors that are specially used in electrochemical descaling circulating water systems and have strong anti-decomposition ability, good stability, and do not significantly affect the electrolysis effect is of great significance and value for the application of electrochemical synergistic chemical technology in circulating water treatment. Summary of the invention

[0006] In order to address the deficiencies in the prior art, the present invention provides a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling. The scale inhibitor has strong anti-electrolysis ability and can effectively resist electrolytic loss while significantly reducing the impact on the electrolytic descaling effect. The scale inhibitor has high stability and excellent scale inhibition and corrosion inhibition performance, so that the circulating water can operate safely and stably at a high concentration rate in the system with electrolytic descaling, reduce the amount of make-up and water discharge, and achieve the goal of zero discharge of circulating water.

[0007] To achieve the above object, the present invention provides a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling, comprising a scale inhibitor component, an acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer, wherein the acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer is prepared by the following method:

[0008] The raw materials acrylic acid and methyl acrylate are heated to 86-92° C. under stirring conditions, and then the initiator ammonium persulfate is added dropwise, and the temperature is maintained to react to obtain an acrylic acid-methyl acrylate solution, and then aminoethanesulfonic acid is added. After it is completely dissolved, concentrated sulfuric acid as a catalyst is finally added, and the temperature is maintained to continue the reaction to obtain an acrylic acid-methyl acrylate-aminoethanesulfonic acid salt terpolymer solution.

[0009] The present invention aims at the problem of mutual interference between existing scale inhibitors and electrolytic descaling, especially the situation that the electrolytic descaling rate decreases after adding the scale inhibitor, and the scale inhibitor is lost by electrolysis, resulting in a decrease in the content of effective scale inhibitor components in the circulating water system. The present invention develops a scale inhibitor component that is particularly suitable for a circulating water system with electrolytic descaling equipment. The novel multi-electrolyte scale inhibitor dispersant is synthesized by using acrylic acid, methyl acrylate and aminoethanesulfonic acid, so that the molecular chain of the copolymer contains strong acid, weak acid and non-ionic groups at the same time, effectively improving the chemical stability, thereby significantly enhancing the anti-electrolysis and anti-decomposition capabilities of the ternary copolymer, and is not easily hydrolyzed or destroyed by acid and alkali, so that it is suitable for use under conditions of high temperature, high pH value, high hardness and high alkalinity. In addition, the acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer also has excellent inhibitory effects on the deposition of iron oxide, calcium phosphate, zinc phosphate and calcium carbonate in water and a high calcium tolerance. It can be combined with corrosion-inhibiting components such as polyphosphates, zinc salts, organic phosphates and other commonly used water treatment agents to form scale inhibitors and corrosion inhibitors specifically for electrochemical descaling circulating water systems, so that the electrochemical descaling technology and scale inhibitors can be well matched for use in circulating water treatment systems, stabilize water quality, and achieve true zero discharge of circulating water on the basis of effectively controlling operating costs.

[0010] As a limitation of the above technical solution, the raw materials acrylic acid, methyl acrylate, ammonium persulfate, aminoethanesulfonic acid and concentrated sulfuric acid used in the preparation of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer are used in a mass ratio of 36g: (40-45)g: (3-3.5)g: (60-70)g: (1-3)g.

[0011] As a limitation of the above technical solution, in the preparation process of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer, ammonium persulfate needs to be prepared into an aqueous solution with a concentration of 0.1 to 0.15 g / mL and added dropwise to the reaction system.

[0012] As a limitation of the above technical solution, the acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer is a colorless to light yellow transparent solution with a solid content of ≥35.0%, easily soluble in water, a pH value of 1% aqueous solution of 3.0-5.0, and a density of 1.10-1.20 g / cm at 20°C. 3 .

[0013] The preparation conditions of the acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer are further defined, including the raw material ratio, the addition method and concentration of the ammonium persulfate used, so as to obtain a scale inhibition component with better performance and more conducive to compounding with a corrosion inhibitor.

[0014] As a limitation of the above technical solution, every hundred parts of scale and corrosion inhibitor includes the following raw material components by mass:

[0015] 2-phosphonobutane-1,2,4-triphosphoric acid PBTC 10-15 parts;

[0016] 10-15 parts of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer;

[0017] Benzotriazole BTA 1-2 parts;

[0018] Water replenishment.

[0019] As a limitation of the above technical solution, every hundred parts of the scale inhibitor and corrosion inhibitor further includes 5-10 parts of hydrolyzed polymaleic anhydride HPMA and / or 5-10 parts of hydroxyethylidene diphosphonic acid HEDP.

[0020] As a limitation of the above technical solution, the scale and corrosion inhibitor is applied to a circulating water system with an electrochemical descaling device, and the scale and corrosion inhibitor is applied to a circulating water system with an electrochemical descaling device for every 1000m 3 / h circulation volume is equipped with an electrochemical descaling equipment. Under the condition of using 50-100ppm of scale inhibitor and corrosion inhibitor, after running for 7 days, the concentration multiple of circulating water is increased by more than 30%, the descaling rate is not less than 25%, and the degradation rate of scale inhibitor and corrosion inhibitor does not exceed 10%.

[0021] The scale inhibitor and corrosion inhibitor of the present invention cooperate with the electrolytic descaling technology to make up for the shortcomings of electrolysis in controlling corrosion and microorganisms. When applied to the circulating water system of electrochemical descaling, on the one hand, it can give full play to the electrolysis to reduce the scale-forming ions in the water and remove salt, thereby increasing the concentration multiple of the circulating water; on the other hand, it can play the role of the scale inhibitor and corrosion inhibitor to enhance the antibacterial and anti-corrosion properties of the circulating water, thereby ensuring the safe and stable operation of the circulating water system; thereby ultimately achieving the safe operation of the circulating water at a high concentration multiple, reducing the amount of make-up and drainage, achieving the zero emission target, and effectively reducing the cost of chemicals and treatment, thereby creating better economic and environmental benefits for the enterprise.

[0022] The present invention also provides a method for preparing the above-mentioned special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling, comprising the following preparation steps:

[0023] a1. Synthesis of acrylic acid-methyl acrylate: acrylic acid and methyl acrylate are added to a reaction vessel with a stirring device respectively, and then distilled water is added, and stirring is started to mix the raw materials evenly. After heating to 86-92°C, an ammonium persulfate aqueous solution is slowly added dropwise, and the addition of the ammonium persulfate aqueous solution is controlled to be completed within 0.5 h. The temperature is maintained at 90±0.5°C for 1-2 h to obtain an intermediate acrylic acid-methyl acrylate solution;

[0024] a2. Synthesis of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer: Add aminoethanesulfonic acid and distilled water to the intermediate acrylic acid-methyl acrylate solution, add concentrated sulfuric acid after complete dissolution, and continue to maintain the temperature at 90±0.5℃ for 3.5-6h. After the reaction is completed, cool to room temperature to obtain an acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer aqueous solution.

[0025] The preparation of the acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer of the present invention comprises the following steps: firstly, acrylic acid and methyl acrylate are used to synthesize an intermediate under the action of an initiator, ammonium persulfate, and then the terpolymer is obtained by reacting the acrylic acid and methyl acrylate with aminoethanesulfonic acid under the action of a catalyst, concentrated sulfuric acid. The preparation process is convenient and easy to control, and the obtained scale inhibition component has stable performance.

[0026] As a limitation of the above technical solution, the preparation method of the special scale inhibitor and corrosion inhibitor for circulating water system based on electrochemical scale removal also includes: step b, mixing and stirring the raw materials in the formula in the order of adding liquid first and then adding solid, and finally adding water and stirring thoroughly to obtain the special scale inhibitor and corrosion inhibitor for circulating water system based on electrochemical scale removal.

[0027] As a limitation of the above technical solution, the mixing process in step b can be heated to no more than 50° C. to ensure that the raw materials are completely dissolved and mixed evenly.

[0028] In the compounding preparation process of the scale and corrosion inhibitor of the present invention, the liquid is first mixed and then the solid is added, and the method of appropriately heating to promote dissolution is combined to make each component completely dissolved, so that a synergistic effect can be obtained.

[0029] In summary, the special scale inhibitor and corrosion inhibitor for circulating water system based on electrochemical descaling of the present invention has the following advantages:

[0030] (1) Significantly reduce the impact on the electrolytic descaling effect.

[0031] The addition of conventional scale inhibitors will have a significant impact on the electrolytic descaling effect. After comparison of small-scale tests, when the addition amount of common organic phosphine or phosphorus-free scale inhibitors is 100 mg / L, the calcium ion removal rate is reduced by about 10% after only 8 hours of operation compared with the direct electrolysis of raw water; when the scale inhibitor of the present invention is used, the calcium ion removal rate is also reduced after 8 hours of operation compared with the direct electrolysis of raw water, but less than 6%. Therefore, after long-term operation, there will be a large difference in the descaling effect, equipment energy consumption and loss of electrochemical equipment.

[0032] (2) Strong anti-electrolysis ability

[0033] Electrolysis has a great influence on currently commonly used scale inhibitors and corrosion inhibitors, especially organic phosphine scale inhibitors and corrosion inhibitors. When the dosing concentration is 100 mg / L, the degradation rate of the organic phosphine scale inhibitor and corrosion inhibitor in the electrochemical device for 72 hours is as high as 24%; the scale inhibitor and corrosion inhibitor of the present invention, when the dosing concentration is 100 mg / L, the degradation rate of the electrochemical device for 72 hours does not exceed 5%, and the anti-electrolysis ability is improved to 2 to 6 times that of conventional agents, which can be adapted to the application under electrochemical descaling conditions.

[0034] (3) Strong anti-decomposition ability and good stability

[0035] After the electrochemical descaling technology is used to increase the concentration multiple, the system discharge volume is reduced, and the residence time of the scale and corrosion inhibitor is increased, which will increase the decomposition rate of the agent per unit time or shorten the decomposition time of the agent. The scale and corrosion inhibitor of the present invention has good stability and strong anti-decomposition ability, and is suitable for the requirement of long agent residence time under high concentration conditions.

[0036] The scale inhibitor and corrosion inhibitor of the present invention is used in a circulating water system that uses an electrolytic device for electrochemical descaling. The specific dosing position can be set at the suction port of the circulating water pool pump, which can significantly reduce the impact on the electrolytic descaling effect, and at the same time has excellent resistance to electrolysis, decomposition, and good scale and corrosion inhibition performance. The scale inhibitor and corrosion inhibitor are used to ensure the stable operation of circulating water in the cooling system and the safety of the system. When the circulating water enters the electrolytic device for electrolytic descaling, the scale inhibitor and corrosion inhibitor in the water can effectively resist the electrolytic effect without affecting the electrolytic descaling rate, ensuring a high electrolytic descaling effect, and achieving zero discharge of circulating water under the premise of effectively controlling operating costs. It has broad market application prospects and good economic, social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 , the sample photo of acrylic acid-methyl acrylate-aminoethanesulfonic acid terpolymer of the present invention is compared with the sample photos of acrylic acid, methyl acrylate and aminoethanesulfonic acid as the raw materials for preparation;

[0038] Figure 2 , comparison of photos of cathode plates of three groups of electrochemical devices obtained from descaling experiments, without any scale inhibitor, with a common organic phosphine scale inhibitor, and with the electrochemical special scale inhibitor of the present invention;

[0039] Figure 3 , comparison of photos of cathode plates of three groups of electrochemical equipment obtained after one week of actual operation, including no addition of any scale inhibitor (a), addition of a commonly used organic phosphine scale inhibitor (b), and addition of the electrochemical special scale inhibitor (c) of the present invention. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The chemical raw materials involved in the following examples and comparative examples are all typical products purchased from the market.

[0042] Example

[0043] This embodiment relates to a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling and its preparation. The formula of the scale inhibitor and corrosion inhibitor is shown in the table below.

[0044]

[0045]

[0046] The preparation of special scale and corrosion inhibitors is carried out according to the following steps:

[0047] a. First prepare acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer

[0048] a1. Synthesis of acrylic acid-methyl acrylate: 36 g acrylic acid and 43 g methyl acrylate were added to a reaction vessel with a stirring device, and then 100 g distilled water was added. The stirring was started to mix the raw materials evenly. The temperature was raised to about 90° C. and an aqueous solution of ammonium persulfate with a concentration of 0.1 g / mL was slowly added dropwise. The total amount of ammonium persulfate added was 3.5 g. The aqueous solution of ammonium persulfate was controlled to be added dropwise within 0.5 h. The temperature was maintained at 90±0.5° C. for 1 to 2 h to obtain an intermediate acrylic acid-methyl acrylate solution.

[0049] a2. Synthesis of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer: add 62 g of aminoethanesulfonic acid and 150 g of distilled water to the intermediate acrylic acid-methyl acrylate solution obtained in step a1, add 1.5 g of concentrated sulfuric acid after complete dissolution, continue to maintain the temperature at 90±0.5°C for 3.5 to 6 hours, and cool to room temperature after the reaction to obtain an acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer aqueous solution;

[0050] The amount of raw materials and reaction conditions in the above preparation process can be adjusted within an appropriate range.

[0051] The acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer aqueous solution is a colorless to light yellow transparent solution. After testing, its solid content is ≥35.0%, and it is easily soluble in water. The pH value of a 1% aqueous solution is 3.0-5.0, and the density at 20°C is 1.10-1.20 g / cm3 The appearance of the raw materials acrylic acid aqueous solution, methyl acrylate, and aminoethanesulfonic acid aqueous solution (commercially available acrylic acid raw materials and aminoethanesulfonic acid raw materials are white powders, which are colorless and transparent solutions after being dissolved in water) and the appearance of the product acrylic acid-methyl acrylate-aminoethanesulfonic acid salt terpolymer aqueous solution are compared. Figure 1 As shown, the color of the aqueous solution of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer is obviously different from the colors of the aqueous solutions of the three raw materials. After simply mixing the three raw material aqueous solutions, a colorless and transparent mixed solution is obtained, which is also obviously different from the color of the aqueous solution of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer.

[0052] b. The raw materials in the formula are mixed in the order of adding the liquid raw material first and then the solid raw material, and finally adding water and stirring thoroughly to obtain a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling;

[0053] The scale and corrosion inhibitor is a colorless to light yellow transparent liquid, and the product indicators are as follows.

[0054] project index Appearance Colorless to light yellow transparent liquid Solid content / % ≥20.0 pH value (1% aqueous solution) 3.0～5.0 <![CDATA[Density (20 °C) / g·cm -3 > 1.05～1.15

[0055] Comparative Example

[0056] The following comparative examples are respectively a commonly used organic phosphine scale inhibitor, a phosphorus-free scale inhibitor and other scale inhibitors used for comparison with the examples of the present invention.

[0057] Comparative Example 1

[0058] A commonly used organic phosphine scale and corrosion inhibitor was selected, and its formula composition was 10 kg of HEDP, 15 kg of acrylic acid-acrylate-phosphonic acid-sulfonate tetrapolymer (purchased from Shandong Kairui Chemical, product model KR-241), 10 kg of PBTCA, 7.5 kg of hydrolyzed polymaleic anhydride, and 57.5 kg of water per 100 kg. The main physical and chemical indicators were: solid content 18%, total phosphorus 7.0%, pH value 3.26, density 1.095 g / cm 3 (20℃).

[0059] Comparative Example 2

[0060] A commonly used phosphorus-free scale and corrosion inhibitor was selected, and its formula composition is 15kg of polyaspartic acid, 10kg of hydrolyzed polymaleic anhydride, and 75kg of water per 100kg. The main physical and chemical indicators are: solid content 11%, pH value 8.89, density 1.035g / cm 3 (20℃).

[0061] Comparative Example 3

[0062] The scale inhibitor is prepared by simply mixing acrylic acid-methyl acrylate copolymer (the preparation of the binary copolymer is the same as in the example) with aminoethanesulfonic acid. The formulation composition is that per 100kg, it contains 15kg of acrylic acid-methyl acrylate copolymer, 10kg of aminoethanesulfonic acid, 10kg of hydrolyzed polymaleic anhydride, and 65kg of water. The main physical and chemical indicators are: solid content 14%, total phosphorus 7.0%, pH value 4.15, density 1.052g / cm 3 (20℃).

[0063] Effect evaluation

[0064] Compare the scale and corrosion inhibitors of the examples with the scale and corrosion inhibitors of the comparative examples, and their mutual influence on the electrochemical descaling reaction.

[0065] (1) The scale inhibition performance of circulating water after adding scale and corrosion inhibitors was evaluated through scale inhibition experiments.

[0066] Scale inhibition experiment: The static method, which is a conventional method for evaluating the scale inhibition performance of water treatment agents, is used. Under the given test conditions, the water supplied by the local water plant is concentrated to a certain multiple in an 80°C water bath. Finally, the hardness and Ca content of the water samples before and after concentration are measured. 2+ The scale inhibition rate is calculated based on the concentration ratio and the actual concentration ratio.

[0067] The static scale inhibition experiment is operated as follows:

[0068] (1) Use the water supplied by the local water plant as the test water, put it into a 1000ml beaker, and add the scale and corrosion inhibitor according to a certain dosage;

[0069] (2) Place the beaker in a water bath at a constant temperature of 80°C and concentrate the water according to the concentration multiple required by the actual operating conditions of the circulating water system, while performing a blank test;

[0070] (3) During the concentration waiting process, measure the total hardness and Ca of the test water. 2+ , Cl - , pH, alkalinity and other indicators, among which the total hardness is determined in accordance with GB / T 6909-2018, Ca 2+ The determination is in accordance with GB / T 15452-2009, the Cl- determination is in accordance with GB / T 15453-2018, the pH determination is in accordance with GB / T 21855-2008, and the alkalinity determination is in accordance with GB / T 15451-2006;

[0071] (4) After the concentration process reaches the required concentration multiple through natural evaporation, take out the beaker and measure the total hardness, Ca 2+ , Cl - , pH, alkalinity and other indicators;

[0072] (5) Calculate the scale inhibition rate according to the following formula.

[0073]

[0074]

[0075] The scale inhibition performance of each scale and corrosion inhibitor was measured and the results are shown in Table 1 below.

[0076]

[0077]

[0078] It can be seen from the experimental data in the above table that the raw water is circulated and concentrated without adding any scale inhibitor, and the calcium retention rate (i.e., scale inhibition rate) in the blank experiment is only about 47%. After adding different scale inhibitors, the calcium retention rate can reach more than 95% at a dosage of 100 mg / L. Compared with the commonly used organic phosphine scale inhibitors, phosphorus-free scale inhibitors, and copolymer scale inhibitors, the scale inhibition performance of the scale inhibitor of the present invention can also reach a calcium retention rate of more than 90% when the dosage is low, such as 20 mg / L, that is, the scale inhibition rate is significantly higher than that of comparative examples 1, 2, and 3 when the dosage concentration is low, which proves that the scale inhibitor of the present invention has a good scale inhibition effect on circulating water (circulating water is operating normally, and no electrolytic descaling treatment is performed), indicating that the scale inhibitor obtained by compounding the modified terpolymer prepared by the present invention can significantly improve the scale inhibition effect.

[0079] (2) Evaluation of the corrosion performance of circulating water after adding scale and corrosion inhibitors through corrosion experiments

[0080] Corrosion experiment: Carry out coupon test in electrochemical experimental equipment, refer to "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotating Coupon Method GB / T18175-2014", the test water temperature is 50℃ (in view of the fact that the heat exchange device in the circulating water system is most affected by corrosion, the test water temperature refers to the temperature of the heat exchange unit of the circulating water system, which is generally around 50℃).

[0081] The corrosion inhibition performance of each scale and corrosion inhibitor was measured, and the results are shown in Table 2 below.

[0082]

[0083]

[0084]

[0085] It can be seen from the above data that the corrosion inhibition performance of each scale inhibitor and corrosion inhibitor increases with the increase of the dosing concentration, so that the corrosion rate of the hanging piece gradually decreases. According to GB / T 50050-2017, the corrosion rate of carbon steel is required to be ≤0.075mm / a and stainless steel is ≤0.005mm / a. The scale inhibitor and corrosion inhibitor of the present invention still shows outstanding corrosion inhibition advantages under the electrolysis of electrochemical equipment. Except that the corrosion rate of stainless steel at the low dosing concentration of 20mg / L is slightly higher than the national standard, the other corrosion rates are lower than the national standard requirements; while the scale inhibitors of comparative examples 1, 2, and 3 are affected by the electrolysis of the electrochemical equipment, and the corrosion rate of stainless steel still exceeds the standard at the dosing concentration of 80-100mg / L, and only the corrosion rate of carbon steel is reduced to below the national standard.

[0086] (3) The electrochemical descaling performance of circulating water after adding scale and corrosion inhibitors was evaluated through descaling experiments.

[0087] Descaling experiment: water samples were added to the electrochemical device and operated for 8 hours at a steady current of 1A to remove calcium carbonate from the water by depositing it on the cathode plate surface. The calcium ion removal rate of the electrochemical device was calculated by calculating the calcium ion concentration before and after the water sample experiment.

[0088] The calculation formula is calcium ion removal rate = (calcium ion concentration before the test - calcium ion concentration after the test) / calcium ion concentration before the test.

[0089] At different dosing concentrations, by comparing the descaling rates with and without the addition of the agent, the effect of the agent on the descaling of the electrochemical device was obtained.

[0090] Electrochemical experimental equipment: DC power supply, ruthenium-iridium coated mesh anode (10×10 cm), Q235 cathode (10×10 cm).

[0091] The electrolytic descaling rate after adding different scale and corrosion inhibitors to the circulating water was determined. The results are shown in Table 3 below.

[0092]

[0093]

[0094]

[0095] According to the experimental results, at different dosing concentrations of the scale inhibitor and corrosion inhibitor in Example 2, the removal rate of calcium ions in the water sample was above 40%, indicating that the agent had little effect on the descaling rate. At different dosing concentrations of the scale inhibitor and corrosion inhibitor in Comparative Example 1, the removal rate of calcium ions in the water sample decreased with the increase of the dosing concentration. When the dosing concentration of the agent reached 100 mg / L, the removal rate of calcium ions was only 35.18%, indicating that the agent had a relatively large effect on the descaling rate. In the experimental results of the scale inhibitor and corrosion inhibitor in Comparative Examples 2 and 3, although the removal rate of calcium ions was close to that of Example 2 at a dosing concentration of 20 to 60 mg / L, the removal rate of calcium ions decreased significantly as the dosing concentration increased to 80 to 100 ppm.

[0096] The photos of the cathode plates of the three electrochemical devices obtained from the above descaling experiments are shown in Figure 2 As shown, the first photo shows the scale precipitation of the cathode plate when no agent is added, and the descaling effect is obvious. The second photo shows the scale precipitation of the cathode plate when 100 mg / L of organic phosphine agent is added, and the descaling effect is significantly reduced. The third photo shows the scale precipitation of the cathode plate when 100 mg / L of electrochemical special agent is added, and the descaling effect is slightly reduced compared with the first photo.

[0097] (4) The stability of each scale and corrosion inhibitor was evaluated through electrolysis experiments.

[0098] Electrolysis experiment: Water samples were added to the electrochemical device and operated at a steady current of 1A for 72 hours.

[0099] Electrochemical experimental equipment: DC power supply, ruthenium-iridium coated mesh anode (10×10 cm), Q235 cathode (10×10 cm).

[0100] At different dosing concentrations, the effect of electrolysis on the degradation of the agent was investigated by measuring the changes in the effective components of the agent in the water samples before and after the experiment.

[0101] The calculation formula is: drug degradation rate = (drug concentration before the test - drug concentration after the test) / drug concentration before the test.

[0102] The concentrations of the scale inhibitors and corrosion inhibitors of Example 2, Comparative Example 2 and Comparative Example 3 were determined by turbidimetry according to GB / T 14421-1993 (the copolymer content and the polyaspartic acid PASP content were determined by turbidimetry, respectively). The concentration of the scale inhibitor and corrosion inhibitor of Comparative Example 1 was determined by spectrophotometry according to GB / T 6913-2008 (the phosphorus content was determined by spectrophotometry).

[0103] The degradation rate of each scale and corrosion inhibitor under electrolysis was determined. The results are shown in Table 4 below.

[0104]

[0105]

[0106]

[0107] According to the experimental results, phosphorus-containing scale and corrosion inhibitors, such as the organic phosphine scale and corrosion inhibitor in comparative example 1, are decomposed into PO under electrolysis. 4 3- (Therefore, the decomposition amount can be determined by measuring the orthophosphorus content), part of PO 4 3- Exists in water in the form of phosphate, part of which is PO 4 3- It binds Ca in water 2+ The higher the concentration, the faster the decomposition rate. Therefore, the electrolysis has a greater impact on the commonly used organic phosphine formulations. The electrolysis rate of the phosphorus-free scale inhibitor of Comparative Example 2 and the copolymer scale inhibitor of Comparative Example 3 is slightly better than that of the organic phosphine agent, but the degradation rate is close to or exceeds 10%, while the degradation rate of the scale inhibitor of the present invention is below 5%, and the anti-electrolysis effect is significantly improved.

[0108] Comprehensive comparison of the above scale inhibition, corrosion inhibition, descaling and electrolysis experimental results shows that the special scale inhibitor and corrosion inhibitor for circulating water system based on electrochemical descaling (hereinafter referred to as electrochemical special scale inhibitor and corrosion inhibitor) of the present invention has the following advantages:

[0109] (1) Significantly reduce the impact on the electrolytic descaling effect.

[0110] The addition of conventional scale inhibitors will have a significant impact on the electrolytic descaling effect. Experiments have found that with the increase in the concentration of conventional scale inhibitors, the removal rate of calcium ions gradually decreases. For example, after adding a common organic phosphine scale inhibitor and running for 8 hours, the removal rate of calcium ions is 45.73% when the raw water is directly electrolyzed, and the removal rate of calcium ions is only 35.18% when the concentration is 100 mg / L; after adding a common phosphorus-free scale inhibitor and running for 8 hours, the removal rate of calcium ions is 48.29% when the raw water is directly electrolyzed, and the removal rate of calcium ions is only 37.71% when the concentration is 100 mg / L. After the scale inhibitor of the present invention is added and running for 8 hours, the removal rate of calcium ions is 47.25% when the raw water is directly electrolyzed, and the removal rate of calcium ions is 41.56% when the concentration is 100 mg / L, which has little effect on electrolytic descaling and will not significantly increase the energy consumption of electrochemical equipment.

[0111] (2) Strong anti-electrolysis ability

[0112] At present, the most widely used scale inhibitor in circulating cooling water system is organic phosphine scale inhibitor. Due to the CP bond in its molecular structure, it has good chemical stability. However, when the circulating water containing organic phosphine scale inhibitor is electrolyzed, it is found that the higher the total phosphorus content of the agent, the higher the degradation rate. In addition to being present in the water in the form of orthophosphorus, a part of it is attached to the cathode plate in the form of calcium phosphate. Therefore, electrolysis has a greater impact on organic phosphine scale inhibitor. For example, the degradation rate of commonly used organic phosphine scale inhibitor is as high as 24% when the maximum dosing concentration is 100 mg / L in electrochemical device for 72 hours; while the degradation rate of commonly used phosphorus-free scale inhibitor is close to 10% when the maximum dosing concentration is 100 mg / L in electrochemical device for 72 hours. The scale inhibitor of the present invention uses raw materials with good stability and is compounded with high molecular multipolymers to increase the anti-electrolysis ability to 2 to 6 times that of conventional agents. The degradation rate of electrochemical device for 72 hours at the maximum dosing concentration of 100 mg / L does not exceed 5%, which can be adapted to the application under electrochemical conditions.

[0113] (3) Strong anti-decomposition ability and good stability

[0114] After the electrochemical technology is used to increase the concentration multiple, the system discharge volume is reduced, and the residence time of the scale and corrosion inhibitor is increased, which will inevitably increase the decomposition rate of the agent per unit time or shorten the decomposition time of the agent, causing problems such as reduced agent concentration and bacterial growth in the circulating water system. The scale and corrosion inhibitor of the present invention has good stability and strong anti-decomposition ability to meet the requirement of long agent residence time under high concentration multiple conditions, and the scale and corrosion inhibitor of the present invention has excellent scale and corrosion inhibition, which can effectively avoid the risks of excessive microorganisms and scaling in the circulating water system.

[0115] The following is the actual operation test of the circulating water system of an enterprise in the National Circular Chemical Industry Park in Shijiazhuang. The make-up water used in the circulating water system is typical water quality that is prone to scaling in the northern region.

[0116] Before the electrochemical equipment was used, the circulating water system used a commonly used organic phosphine scale inhibitor (the scale inhibitor formula used was the same as that of Comparative Example 1) and operated at a concentration multiple of about 2.0 for a long time.

[0117] Electrochemical equipment was added to the circulating water system, but no scale inhibitors were added. The system used two sets of electrochemical equipment corresponding to 2000m3 of circulating water. 3 / h circulation rate, the electrochemical equipment operating conditions are 20V voltage, 300A current, one week of operation, the cathode plate scaling in the electrochemical equipment is as follows Figure 3 As shown in a, the measured descaling rate is 31%, and the circulating water concentration multiple reaches 2.9. Although the circulating water system can operate, there is still a certain scaling phenomenon, and the microbial contamination and corrosion problems in the system are serious.

[0118] A commonly used organic phosphine scale inhibitor (same as comparative example 1) was added to the circulating water system of the electrochemical device at a dosage of 100 ppm. After one week of operation, the scale formation of the cathode plate in the electrochemical device was as follows: Figure 3 As shown in b, the descaling effect is significantly reduced. The measured descaling rate is 21%, the circulating water concentration multiple is 2.3, and the degradation rate of the scale inhibitor and corrosion inhibitor due to electrolysis is 33.7%.

[0119] The scale inhibitor was replaced with the electrochemical special scale inhibitor of the present invention (the specific formula adopts Example 2), the dosage was 100 ppm, and the scale was run for one week. The scale formation of the cathode plate in the electrochemical device was as follows: Figure 3 As shown in Figure c, the problem of affected electrolytic descaling effect has been significantly alleviated. The measured descaling rate is 28%, the circulating water concentration multiple is 2.7, and the degradation rate of scale inhibitor is also reduced to 9.6%. The scaling, microbial contamination and corrosion problems of the circulating water system have been effectively solved.

[0120] Through the above comparison, it is obvious that the electrochemical special scale inhibitor and corrosion inhibitor of the present invention significantly reduces the impact on the descaling effect of electrolysis, and according to the actual operation results, the electrochemical special scale inhibitor and corrosion inhibitor of the present invention is used in conjunction with the electrochemical descaling equipment, and the descaling rate of circulating water is not less than 25%, and the concentration multiple of circulating water is increased by more than 30% compared with the concentration multiple of not using electrochemical equipment and only using scale inhibitor and corrosion inhibitor (that is, compared with the concentration multiple of 2.0), and the degradation rate of scale inhibitor and corrosion inhibitor by electrolysis does not exceed 10%, which is suitable for the efficient, stable and safe operation of the circulating water system with electrochemical descaling equipment.

[0121] In summary, the special scale inhibitor and corrosion inhibitor for circulating water system based on electrochemical descaling of the present invention has strong anti-electrolysis ability, and significantly reduces the influence on the electrochemical descaling effect, and can cooperate with electrochemical descaling equipment to stabilize the water quality of circulating water; at the same time, it also has good scale inhibition and corrosion inhibition performance, and has excellent inhibitory effect and high calcium tolerance on the deposition of iron oxide, calcium phosphate, zinc phosphate and calcium carbonate in water; it has excellent stability and wide applicability, and can be used under high temperature, high pH value, high hardness and high alkalinity conditions; and has good compatibility with commonly used water treatment agents such as polyphosphates, zinc salts, and organic phosphates.

Claims

1. Application of a scale and corrosion inhibitor in a circulating water system with an electrochemical descaling device, characterized in that: Every hundred parts of scale and corrosion inhibitor includes the following raw material components by mass: 10-15 parts of 2-phosphonobutane-1,2,4-triphosphoric acid; 10-15 parts of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer; 1-2 parts of benzotriazole; Water replenishment; The scale and corrosion inhibitor is prepared by the following method: a. First prepare acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer: a1. Synthesis of acrylic acid-methyl acrylate: Add acrylic acid and methyl acrylate into a reaction vessel with a stirring device respectively, then add distilled water, start stirring to mix the raw materials evenly, raise the temperature to 86-92°C, slowly inject ammonium persulfate aqueous solution in a dropwise manner, control the addition of ammonium persulfate aqueous solution to be completed within 0.5 h, maintain the temperature at 90±0.5°C for 1-2 h, and obtain an intermediate acrylic acid-methyl acrylate solution; a2. Synthesis of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer: Add aminoethanesulfonic acid and distilled water to the intermediate acrylic acid-methyl acrylate solution, add concentrated sulfuric acid after complete dissolution, continue to maintain the temperature at 90±0.5℃ for 3.5~6h, and cool to room temperature after the reaction to obtain an acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer aqueous solution; The mass ratio of acrylic acid, methyl acrylate, ammonium persulfate, aminoethanesulfonic acid and concentrated sulfuric acid is 36g: (40-45)g: (3-3.5)g: (60-70)g: (1-3)g; b. The raw materials in the formula are mixed and stirred in the order of adding liquid first and then solid, and finally water is added and stirred thoroughly to obtain a special scale inhibitor and corrosion inhibitor for a circulating water system based on electrochemical descaling; Scale and corrosion inhibitors are used in circulating water systems with electrochemical descaling equipment. 3 / h circulation volume is equipped with an electrochemical descaling equipment. Under the condition of using 50~100ppm of scale inhibitor and corrosion inhibitor, after running for 7 days, the concentration multiple of circulating water is increased by more than 30%, the descaling rate is not less than 25%, and the degradation rate of scale inhibitor and corrosion inhibitor does not exceed 10%.

2. The use of the scale and corrosion inhibitor according to claim 1 in a circulating water system with an electrochemical descaling device, characterized in that: In the preparation process of acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer, ammonium persulfate needs to be prepared into an aqueous solution with a concentration of 0.1-0.15 g / mL and added dropwise to the reaction system.

3. The use of the scale and corrosion inhibitor according to claim 1 in a circulating water system having an electrochemical descaling device, characterized in that: The acrylic acid-methyl acrylate-aminoethanesulfonate terpolymer is a colorless to light yellow transparent solution with a solid content of ≥35.0%. It is easily soluble in water, and the pH value of a 1% aqueous solution is 3.0-5.

0. The density at 20°C is 1.10-1.20 g / cm 3 .

4. The use of the scale and corrosion inhibitor according to claim 1 in a circulating water system having an electrochemical descaling device, characterized in that: The scale inhibitor and corrosion inhibitor also include 5-10 parts of hydrolyzed polymaleic anhydride and / or 5-10 parts of hydroxyethylidene diphosphonic acid per 100 parts.

5. The use of the scale and corrosion inhibitor according to claim 1 in a circulating water system having an electrochemical descaling device, characterized in that: The mixing process in step b can be heated to no more than 50° C. to ensure that the raw materials are completely dissolved and mixed evenly.

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