A high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method

Abstract

This invention provides a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method, belonging to the field of water treatment agent technology. This application introduces a sulfonated polycarboxylic acid copolymer, which inhibits crystal nucleation through the chelating effect of its carboxylic acid groups, enhances dispersibility and hard water tolerance through sulfonic acid groups, and regulates molecular weight through isopropanol, enabling it to adsorb and interfere with the normal growth of microcrystals, promoting the formation of loose scale that is easy to remove. A polyether graft copolymer, as a high-efficiency dispersant, has its main chain responsible for adsorbing and anchoring the already formed microscale, while its extended polyether side chains form a steric barrier layer, encapsulating and stably suspending the particles, preventing scale aggregation and growth. These two components synergistically constitute a scale inhibition defense line, and together with additives such as composite amines and oxygen scavengers in the system, they form a comprehensive protective network, thereby ensuring the long-term stable operation of the boiler system.

Description

Technical Field

[0001] This invention belongs to the field of water treatment agent technology, and relates to a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method. Background Technology

[0002] In modern industrial production, circulating cooling water and boiler water systems are crucial for ensuring stable equipment operation and improving energy efficiency. However, the long-term efficient operation of these systems faces two major challenges: scale buildup and metal corrosion. Scale, especially calcium, magnesium hardness scale, phosphate scale, and silica scale, forms an insulating layer on heat exchange surfaces, severely reducing heat transfer efficiency, increasing energy consumption, and even causing localized overheating that leads to equipment damage. Corrosion, on the other hand, thins pipe walls, shortens equipment lifespan, and may cause major safety accidents such as perforation and leakage.

[0003] Most existing technologies employ polymers with a single structure, such as traditional polyacrylic acid and its simple copolymers, attempting to simultaneously perform multiple functions, including inhibiting crystal nucleation, distorting crystal lattice structures, and dispersing suspended particles. However, these functions present an inherent contradiction in molecular design: efficient threshold inhibition requires polymers with low molecular weights to rapidly diffuse to nucleation sites, while strong dispersing capabilities depend on longer molecular chains to provide sufficient steric hindrance. This makes it impossible to achieve any single function, failing to meet the urgent needs of modern industry for long-cycle, high-concentration-rate operation. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method. This application introduces a sulfonated polycarboxylic acid copolymer, which inhibits crystal nucleation through the chelating effect of its carboxylic acid groups, enhances dispersibility and hard water tolerance through sulfonic acid groups, and regulates molecular weight through isopropanol, enabling it to adsorb and interfere with the normal growth of microcrystals, promoting the formation of loose scale that is easy to remove. A polyether graft copolymer, as a highly efficient dispersant, has its main chain responsible for adsorbing and anchoring the already formed microscale, while its extended polyether side chains form a steric barrier layer, encapsulating and stably suspending the particles, preventing scale aggregation and growth. These two components synergistically constitute a scale inhibition defense line, and together with additives such as composite amines and oxygen scavengers in the system, they construct a comprehensive protective network, thereby ensuring the long-term stable operation of the boiler system.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a high-efficiency boiler scale and corrosion inhibitor composite agent, the method comprising:

[0007] S1: Isopropanol and deionized water are added to a reaction vessel, and the pH value is adjusted with sulfuric acid before heating to obtain the reaction base liquid; maleic anhydride is dispersed in isopropanol to obtain a slurry; acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are dispersed in deionized water to form a monomer solution; ammonium persulfate is dispersed in deionized water to form a first initiator solution; simultaneously, the slurry, monomer solution and first initiator solution are added dropwise to the reaction base liquid to obtain reaction solution A; after the addition is completed, the temperature is maintained, and after cooling, the pH value is adjusted with sodium hydroxide solution to obtain a sulfonated polycarboxylic acid copolymer solution;

[0008] S2: Acrylic acid and vinylpyrrolidone are dispersed in deionized water to form a main chain monomer solution; polyethylene glycol methacrylate is dispersed in deionized water to form a side chain monomer solution; ammonium persulfate is dispersed in deionized water to form a second initiator solution; deionized water is added to a reaction vessel, and after heating, the main chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution B. The reaction is stirred, and the side chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution C. The reaction is kept at a constant temperature, and after cooling, the pH value is adjusted with sodium hydroxide solution to obtain a polyether graft copolymer solution.

[0009] S3: Hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide and hydroquinone are added sequentially to deionized water to obtain the basic additive stock solution; sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution and composite amine mixture are added sequentially to obtain the composite agent stock solution. After stirring evenly, the pH value is adjusted with sodium hydroxide solution to obtain the high-efficiency boiler scale and corrosion inhibitor composite agent.

[0010] As a preferred technical solution of the present invention, in step S1, the amount of isopropanol in the reaction base liquid accounts for 40-60% of the total amount of isopropanol in S1. For example, it can be 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58% or 60%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0011] In some optional embodiments, the mass ratio of isopropanol to deionized water in the reaction substrate is 1:(15-25), for example, it can be 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24 or 1:25, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0012] In some optional embodiments, the mass fraction of the sulfuric acid is 10-30 wt.%, for example, it can be 10 wt.%, 12 wt.%, 14 wt.%, 16 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, 24 wt.%, 26 wt.%, 28 wt.%, or 30 wt.%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0013] In some alternative embodiments, the isopropanol is mixed with deionized water and the pH is adjusted to 2.0-3.5 with sulfuric acid. For example, the pH can be adjusted to 2.0, 2.15, 2.30, 2.45, 2.60, 2.75, 2.90, 3.05, 3.20, 3.35 or 3.50, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] In some optional embodiments, the temperature of the reaction substrate is 80-85°C, for example, it can be 80.0°C, 80.5°C, 81.0°C, 81.5°C, 82.0°C, 82.5°C, 83.0°C, 83.5°C, 84.0°C, 84.5°C or 85.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0015] In some optional embodiments, the mass ratio of maleic anhydride to isopropanol in the slurry is 1:(1.5-2.5), for example, it can be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4 or 1:2.5, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0016] In some alternative embodiments, the total mass ratio of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid in the monomer solution to deionized water is 1:(1.2-1.5), for example, it can be 1:1.20, 1:1.23, 1:1.26, 1:1.29, 1:1.32, 1:1.35, 1:1.38, 1:1.41, 1:1.44, 1:1.47 or 1:1.50, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0017] In some alternative embodiments, the mass concentration of the first initiator solution is 8-15%, for example, it may be 8.0%, 8.7%, 9.4%, 10.1%, 10.8%, 11.5%, 12.2%, 12.9%, 13.6%, 14.3% or 15.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the molar ratio of acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid in reaction solution A is (3.0-5.0):(2.0-4.0):1.0, for example, it can be (3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8 or 5.0):(2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0):1.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the total molar ratio of ammonium persulfate to monomers acrylic acid, maleic anhydride and 2-acrylamido-2-methylpropanesulfonic acid in reaction solution A is 1:(30-60), for example, it can be 1:30, 1:33, 1:36, 1:39, 1:42, 1:45, 1:48, 1:51, 1:54, 1:57 or 1:60, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the reaction solution A is kept at a temperature of 1.5-2.0 h, for example, it can be 1.50 h, 1.55 h, 1.60 h, 1.65 h, 1.70 h, 1.75 h, 1.80 h, 1.85 h, 1.90 h, 1.95 h or 2.00 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the sodium hydroxide solution has a mass fraction of 20-40 wt.%, for example, it may be 20 wt.%, 22 wt.%, 24 wt.%, 26 wt.%, 28 wt.%, 30 wt.%, 32 wt.%, 34 wt.%, 36 wt.%, 38 wt.%, or 40 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0022] In some alternative embodiments, the pH of the reaction solution A is adjusted to 7.0-8.0 with sodium hydroxide solution after cooling. For example, the pH can be adjusted to 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9 or 8.0, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the solid content of the sulfonated polycarboxylic acid copolymer solution is 38-42%, for example, it can be 38.0%, 38.4%, 38.8%, 39.2%, 39.6%, 40.0%, 40.4%, 40.8%, 41.2%, 41.6% or 42.0%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0024] As a preferred technical solution of the present invention, in step S2, the mass concentration of the main chain monomer solution is 50-65%, for example, it can be 50.0%, 51.5%, 53.0%, 54.5%, 56.0%, 57.5%, 59.0%, 60.5%, 62.0%, 63.5% or 65.0%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the mass concentration of the side-chain monomer solution is 50-70%, for example, it can be 50%, 52%, 54%, 56%, 58%, 60%, 62%, 64%, 66%, 68% or 70%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In some alternative embodiments, the mass concentration of the second initiator solution is 1-5%, for example, it can be 1.0%, 1.4%, 1.8%, 2.2%, 2.6%, 3.0%, 3.4%, 3.8%, 4.2%, 4.6% or 5.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] In some optional embodiments, the deionized water is heated to 73-77°C, for example, 73.0°C, 73.4°C, 73.8°C, 74.2°C, 74.6°C, 75.0°C, 75.4°C, 75.8°C, 76.2°C, 76.6°C, or 77.0°C, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0028] In some optional embodiments, the amount of ammonium persulfate in reaction solution B accounts for 30-40% of the total amount of ammonium persulfate in S2, for example, it can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the reaction time of the reaction solution B is 1-1.5 h, for example, it can be 1.00 h, 1.05 h, 1.10 h, 1.15 h, 1.20 h, 1.25 h, 1.30 h, 1.35 h, 1.40 h, 1.45 h or 1.50 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the reaction solution C is kept warm for 1.5-2.5 hours, for example, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours or 2.5 hours, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the molar ratio of acrylic acid, vinylpyrrolidone, and polyethylene glycol methacrylate is (3.0-6.0):(1.0-2.0):1.0, for example, it can be (3.0, 3.3, 3.6, 3.9, 4.2, 4.5, 4.8, 5.1, 5.4, 5.7, or 6.0):(1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0):1.0, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the total molar ratio of ammonium persulfate in S2 to the total molar ratio of monomeric acrylic acid, vinylpyrrolidone and polyethylene glycol methacrylate is 1:(150-250), for example, it can be 1:150, 1:160, 1:170, 1:180, 1:190, 1:200, 1:210, 1:220, 1:230, 1:240 or 1:250, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the pH of the reaction solution C is adjusted to 7.0-8.5 with sodium hydroxide solution after cooling. For example, the pH can be adjusted to 7.00, 7.15, 7.30, 7.45, 7.60, 7.75, 7.90, 8.05, 8.20, 8.35 or 8.50, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the solid content of the polyether graft copolymer solution is 38-42%, for example, it can be 38.0%, 38.4%, 38.8%, 39.2%, 39.6%, 40.0%, 40.4%, 40.8%, 41.2%, 41.6% or 42.0%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0035] As a preferred technical solution of the present invention, in step S3, the mass ratio of cyclohexylamine, diethylaminoethanol and morpholine in the composite amine mixture is (0.8-1.2):2:(1-1.5), for example, it can be (0.80, 0.84, 0.88, 0.92, 0.96, 1.00, 1.04, 1.08, 1.12, 1.16 or 1.20):2:(1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45 or 1.50), but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0036] In some optional embodiments, the mass ratio of the sulfonated polycarboxylic acid copolymer solution, the polyether graft copolymer solution, hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, hydroquinone, and the complex amine mixture is (15-25):(15-25):(5-10):(0.8-2):(3-6):(0.5-1):(8-18), for example, it can be (15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25):(15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25):(5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8 5, 9.0, 9.5 or 10.0): (0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2): (3.0, 3.3, 3.6, 3.9, 4.2, 4.5, 4.8, 5.1, 5.4, 5.7 or 6.0): (0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 1): (8, 9, 10, 11, 12, 13, 14, 15, 16, 17 or 18), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0037] After the compound drug stock solution is stirred evenly, the pH is adjusted to 8.9-9 with sodium hydroxide solution.

[0038] Secondly, the present invention provides a high-efficiency boiler scale and corrosion inhibitor composite agent.

[0039] This application introduces a sulfonated polycarboxylic acid copolymer that effectively inhibits scale formation in its initial stage. The copolymer is composed of three monomers: acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid. The acrylic acid and maleic anhydride units hydrolyze after polymerization, providing a high density of carboxylic acid functional groups on the polymer backbone. These negatively charged groups can act as chelating sites, binding with calcium in the water. 2+ Mg 2+ The interaction between scale-forming cations helps reduce the effective activity of ions in the water, thereby inhibiting the formation of scale nuclei to some extent. Secondly, the sulfonic acid group in the 2-acrylamido-2-methylpropanesulfonic acid monomer is a strong acid group that tends to ionize highly in water. Its strong polarity and steric hindrance help improve the polymer's dispersion ability, positively impacting the dispersion of suspended particles such as calcium phosphate and iron oxide. Simultaneously, the presence of the sulfonic acid group helps improve the polymer's calcium ion tolerance, allowing it to maintain its dissolved state and activity in high-hardness, high-alkalinity water, reducing the risk of self-precipitation failure. Furthermore, the addition of isopropanol as a chain transfer agent in the polymerization system regulates the polymer's molecular weight. A moderately reduced molecular weight helps improve the mobility and diffusion rate of polymer chains, enabling them to adsorb more quickly onto the surface of newly formed microcrystals. By occupying and interfering with lattice growth points, it affects the normal growth pattern of crystals, promoting the formation of a more loosely structured scale.

[0040] This application introduces a polyether graft copolymer as a highly efficient dispersant to treat tiny scale particles that failed to be suppressed in the previous stage. This copolymer has a main-chain-side-chain grafted structure, achieving both adsorption and dispersion functions. Its main chain is copolymerized from acrylic acid and vinylpyrrolidone. The carboxyl groups on the main chain enable it to anchor to the surface of scale particles such as calcium carbonate and calcium sulfate through electrostatic attraction or chemisorption. The introduction of vinylpyrrolidone units enhances the hydrophilicity of the main chain and its affinity for colloidal particles such as iron oxides. Furthermore, the polymer side chains are composed of the macromonomer polyethylene glycol monomethacrylate. When the main chain adsorbs onto the surface of scale particles, these hydrophilic long polyether side chains extend fully into the aqueous phase, forming a three-dimensional shielding layer around the particles. This shielding layer physically prevents the particles from approaching each other and agglomerating through steric hindrance, thereby preventing the transformation of soft scale into hard scale. This structure encapsulates the adsorbed particles, altering their surface properties, ultimately suspending them in the water and removing them with boiler blowdown.

[0041] This application also exhibits synergistic enhancement. Regarding scale inhibition, the sulfonated polycarboxylic acid copolymer utilizes its ability to inhibit and lattice distortion, preventing scale formation at both the ionic and nucleation levels. Meanwhile, the polyether graft copolymer coats and disperses the few small particles that do form. Together, they form a multi-layered defense system from ions to particles, covering the entire scale formation process. Secondly, there is synergy between scale inhibition and corrosion inhibition: the combination of complex amines (cyclohexylamine, diethylaminoethanol, and morpholine), utilizing their different steam-water partition coefficients, ensures a suitable pH value is maintained in the boiler body, steam pipelines, and condensate system, inhibiting acid corrosion; hydrazine, as the main chemical deoxygenator, and hydroquinone, as a reducing agent, synergistically promote the deoxygenation process, reducing dissolved oxygen content. The stable hydrochemical environment created by these corrosion inhibitors ensures the effectiveness of the sulfonated polycarboxylic acid copolymer and the polyether graft copolymer. Finally, hydroxyethylidene diphosphonic acid, as a small molecule chelating agent, synergistically works with the polymer, while methylbenzotriazole protects the copper, together constructing a comprehensive protection network to achieve long-term safe and stable boiler operation.

[0042] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0043] This application introduces sulfonated polycarboxylic acid copolymers. The high-density carboxylic acid groups on its main chain (derived from acrylic acid and maleic anhydride) bind scale-forming cations in water through chelation, inhibiting crystal nucleation. Secondly, the introduced sulfonic acid groups (derived from 2-acrylamido-2-methylpropanesulfonic acid monomer) not only enhance the polymer's ability to disperse suspended particles but also improve its stability and activity in hard water. Through the regulation of molecular weight by the chain transfer agent isopropanol, the polymer can adsorb and interfere with the normal growth of microcrystals, promoting the formation of loose scale that is easy to remove.

[0044] This application introduces a polyether graft copolymer as a highly efficient dispersant to stabilize and remove existing microscale particles. This copolymer achieves functional division through a main-chain-side-chain grafting structure: its main chain (containing acrylic acid and vinylpyrrolidone units) is responsible for anchoring to the surface of scale particles through adsorption; while its hydrophilic long polyether side chains extend around the particles, forming a physical shielding layer. This shielding layer effectively prevents particle aggregation and growth through steric hindrance, stably dispersing them in water, and ultimately removing them with wastewater discharge.

[0045] This application demonstrates multiple synergistic enhancements. Regarding scale inhibition, the sulfonated polycarboxylic acid copolymer inhibits scale formation at both the ion and nucleation stages, while the polyether graft copolymer treats existing microparticles, achieving coating and dispersion. In terms of functional synergy, various corrosion inhibitors create favorable conditions for the operation of the sulfonated polycarboxylic acid copolymer and the polyether graft copolymer by stabilizing the hydrochemical environment. Through cooperation with other additives, a protective network is constructed to ensure the long-term stable operation of the boiler system. Detailed Implementation

[0046] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that employ any obvious substitutions and modifications made to the embodiments described herein.

[0047] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0048] Example 1

[0049] This embodiment provides a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method. The preparation method of the high-efficiency boiler scale and corrosion inhibitor composite agent specifically includes the following steps:

[0050] S1: Isopropanol (55% of the total isopropanol content) and deionized water are added to a reaction vessel, with a mass ratio of isopropanol to deionized water of 1:22. The pH is adjusted to 3.0 with 15 wt.% sulfuric acid, and the temperature is raised to 84°C to obtain the reaction base solution. Maleic anhydride is dispersed in isopropanol to obtain a slurry, with a mass ratio of maleic anhydride to isopropanol of 1:2.2. Acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are dispersed in deionized water to form a monomer solution, with a total mass ratio of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid to deionized water of 1:1.4. Ammonium persulfate is dispersed... A first initiator solution with a mass concentration of 12% was formed by dispersing it in deionized water. Simultaneously, slurry, monomer solution, and the first initiator solution were added dropwise to the reaction substrate to obtain reaction solution A, wherein the molar ratio of acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 4.5:3.5:1.0, and the total molar ratio of ammonium persulfate to monomers acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 1:50. After the addition was completed, the solution was kept at a temperature of 1.8 h, and after cooling, the pH value was adjusted to 7.8 with a 30 wt.% sodium hydroxide solution to obtain a sulfonated polycarboxylic acid copolymer solution with a solid content of 41%.

[0051] S2: Acrylic acid and vinylpyrrolidone are dispersed in deionized water to form a main-chain monomer solution with a mass concentration of 60%; polyethylene glycol methacrylate is dispersed in deionized water to form a side-chain monomer solution with a mass concentration of 65%; ammonium persulfate is dispersed in deionized water to form a second initiator solution with a mass concentration of 4%; deionized water is added to a reaction vessel, the temperature is raised to 76°C, and the main-chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution B, wherein the amount of ammonium persulfate used in reaction solution B is the same as the total amount of ammonium persulfate used in S2. The reaction mixture was stirred for 1.3 hours, and then a side-chain monomer solution and a second initiator solution were added dropwise to obtain reaction solution C. The mixture was kept at this temperature for 2.2 hours. The molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate was 5.0:1.8:1.0. The total molar ratio of ammonium persulfate to the total molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate in S2 was 1:220. After cooling, the pH was adjusted to 8.0 with sodium hydroxide solution to obtain a polyether graft copolymer solution with a solid content of 39%.

[0052] S3: Hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, and hydroquinone were added sequentially to deionized water to obtain a basic additive stock solution; sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, and composite amine mixture were added sequentially to obtain a composite agent stock solution, wherein the composite amine mixture was obtained by premixing cyclohexylamine, diethylaminoethanol, and morpholine in a mass ratio of 1.1:2:1.3; the mass ratios of sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, hydroquinone, and composite amine mixture were 22:17:8:1.5:5:0.6:15, respectively; after stirring evenly, the pH value was adjusted to 8.9 with sodium hydroxide solution to obtain a high-efficiency boiler scale and corrosion inhibitor composite agent.

[0053] Example 2

[0054] This embodiment provides a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method. The preparation method of the high-efficiency boiler scale and corrosion inhibitor composite agent specifically includes the following steps:

[0055] S1: Isopropanol (40% of the total isopropanol content) and deionized water are added to a reaction vessel, with a mass ratio of isopropanol to deionized water of 1:15. The pH is adjusted to 2.0 with 30 wt.% sulfuric acid, and the temperature is raised to 80°C to obtain the reaction base solution. Maleic anhydride is dispersed in isopropanol to obtain a slurry, with a mass ratio of maleic anhydride to isopropanol of 1:1.5. Acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are dispersed in deionized water to form a monomer solution, with a total mass ratio of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid to deionized water of 1:1.2. Ammonium persulfate is added... A first initiator solution with a mass concentration of 8% was formed by dispersing in deionized water. Simultaneously, slurry, monomer solution, and the first initiator solution were added dropwise to the reaction substrate to obtain reaction solution A, wherein the molar ratio of acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 3.0:2.0:1.0, and the total molar ratio of ammonium persulfate to monomers acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 1:30. After the addition was completed, the mixture was kept at a constant temperature for 1.5 hours. After cooling, the pH value was adjusted to 7.0 with a 20 wt.% sodium hydroxide solution to obtain a sulfonated polycarboxylic acid copolymer solution with a solid content of 38%.

[0056] S2: Acrylic acid and vinylpyrrolidone are dispersed in deionized water to form a 50% (w / w) main chain monomer solution; polyethylene glycol methacrylate is dispersed in deionized water to form a 50% (w / w) side chain monomer solution; ammonium persulfate is dispersed in deionized water to form a 1% (w / w) second initiator solution; deionized water is added to a reaction vessel, the temperature is raised to 73°C, and the main chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution B, wherein the amount of ammonium persulfate used in reaction solution B accounts for a percentage of the total amount of ammonium persulfate used in S2. 30% of the amount was added, and the mixture was stirred for 1 hour. A side-chain monomer solution and a second initiator solution were then added dropwise to obtain reaction solution C. The mixture was kept at this temperature for 1.5 hours. The molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate was 3.0:1.0:1.0. The total molar ratio of ammonium persulfate to the total molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate in S2 was 1:150. After cooling, the pH was adjusted to 7.0 with sodium hydroxide solution to obtain a polyether graft copolymer solution with a solid content of 42%.

[0057] S3: Hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, and hydroquinone were added sequentially to deionized water to obtain a basic additive stock solution; sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, and composite amine mixture were added sequentially to obtain a composite agent stock solution, wherein the composite amine mixture was obtained by premixing cyclohexylamine, diethylaminoethanol, and morpholine in a mass ratio of 0.8:2:1; the mass ratios of sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, hydroquinone, and composite amine mixture were 15:25:5:1.8:3:0.8:8, respectively; after stirring evenly, the pH value was adjusted to 9 with sodium hydroxide solution to obtain a high-efficiency boiler scale and corrosion inhibitor composite agent.

[0058] Example 3

[0059] This embodiment provides a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method. The preparation method of the high-efficiency boiler scale and corrosion inhibitor composite agent specifically includes the following steps:

[0060] S1: Isopropanol (45% of the total isopropanol content) and deionized water are added to a reaction vessel, with a mass ratio of isopropanol to deionized water of 1:18. The pH is adjusted to 2.5 with 20 wt.% sulfuric acid, and the temperature is raised to 81°C to obtain the reaction base solution. Maleic anhydride is dispersed in isopropanol to obtain a slurry, with a mass ratio of maleic anhydride to isopropanol of 1:1.8. Acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are dispersed in deionized water to form a monomer solution, with a total mass ratio of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid to deionized water of 1:1.3. Ammonium persulfate is then dispersed... A 10% (w / w) first initiator solution was formed by dispersing it in deionized water. Simultaneously, slurry, monomer solution, and the first initiator solution were added dropwise to the reaction substrate to obtain reaction solution A, wherein the molar ratio of acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 3.5:2.5:1.0, and the total molar ratio of ammonium persulfate to monomers acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 1:40. After the addition was completed, the solution was kept at a constant temperature for 1.6 hours. After cooling, the pH value was adjusted to 7.2 with a 40 wt.% sodium hydroxide solution to obtain a sulfonated polycarboxylic acid copolymer solution with a solid content of 39%.

[0061] S2: Acrylic acid and vinylpyrrolidone are dispersed in deionized water to form a main-chain monomer solution with a mass concentration of 55%; polyethylene glycol methacrylate is dispersed in deionized water to form a side-chain monomer solution with a mass concentration of 55%; ammonium persulfate is dispersed in deionized water to form a second initiator solution with a mass concentration of 2%; deionized water is added to a reaction vessel, the temperature is raised to 74°C, and the main-chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution B, wherein the amount of ammonium persulfate used in reaction solution B is the same as the total amount of ammonium persulfate used in S2. The reaction mixture was stirred for 1.1 h, and then a side-chain monomer solution and a second initiator solution were added dropwise to obtain reaction solution C. The mixture was kept at this temperature for 1.8 h. The molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate was 4.0:1.2:1.0. The total molar ratio of ammonium persulfate to the total molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate in S2 was 1:180. After cooling, the pH was adjusted to 7.5 with sodium hydroxide solution to obtain a polyether graft copolymer solution with a solid content of 41%.

[0062] S3: Hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, and hydroquinone were added sequentially to deionized water to obtain a basic additive stock solution; sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, and composite amine mixture were added sequentially to obtain a composite agent stock solution, wherein the composite amine mixture was obtained by premixing cyclohexylamine, diethylaminoethanol, and morpholine in a mass ratio of 0.9:2:1.1; the mass ratios of sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, hydroquinone, and composite amine mixture were 18:23:6:2:4:1:10, respectively; after stirring evenly, the pH value was adjusted to 8.9 with sodium hydroxide solution to obtain a high-efficiency boiler scale and corrosion inhibitor composite agent.

[0063] Example 4

[0064] This embodiment provides a high-efficiency boiler scale and corrosion inhibitor composite agent and its preparation method. The preparation method of the high-efficiency boiler scale and corrosion inhibitor composite agent specifically includes the following steps:

[0065] S1: Isopropanol (60% of the total isopropanol content) and deionized water are added to a reaction vessel, with a mass ratio of isopropanol to deionized water of 1:25. The pH is adjusted to 3.5 with 10 wt.% sulfuric acid, and the temperature is raised to 85°C to obtain the reaction base solution. Maleic anhydride is dispersed in isopropanol to obtain a slurry, with a mass ratio of maleic anhydride to isopropanol of 1:2.5. Acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are dispersed in deionized water to form a monomer solution, with a total mass ratio of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid to deionized water of 1:1.5. Ammonium persulfate is then dispersed... A first initiator solution with a mass concentration of 15% was formed by dispersing it in deionized water. Simultaneously, slurry, monomer solution, and the first initiator solution were added dropwise to the reaction substrate to obtain reaction solution A, wherein the molar ratio of acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 5.0:4.0:1.0, and the total molar ratio of ammonium persulfate to monomers acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid was 1:60. After the addition was completed, the solution was kept at a temperature of 2.0 h, and after cooling, the pH value was adjusted to 8.0 with a 35 wt.% sodium hydroxide solution to obtain a sulfonated polycarboxylic acid copolymer solution with a solid content of 42%.

[0066] S2: Acrylic acid and vinylpyrrolidone are dispersed in deionized water to form a main-chain monomer solution with a mass concentration of 65%; polyethylene glycol methacrylate is dispersed in deionized water to form a side-chain monomer solution with a mass concentration of 70%; ammonium persulfate is dispersed in deionized water to form a second initiator solution with a mass concentration of 5%; deionized water is added to a reaction vessel, the temperature is raised to 77°C, and the main-chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution B, wherein the amount of ammonium persulfate used in reaction solution B is the same as the total amount of ammonium persulfate used in S2. 40% of the monomer was added, and the mixture was stirred for 1.5 h. Then, a side-chain monomer solution and a second initiator solution were added dropwise to obtain reaction solution C. The mixture was kept at this temperature for 2.5 h. The molar ratio of acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate was 6.0:2.0:1.0. The total molar ratio of ammonium persulfate in S2 to the total molar ratio of the monomers acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate was 1:250. After cooling, the pH was adjusted to 8.5 with sodium hydroxide solution to obtain a polyether graft copolymer solution with a solid content of 38%.

[0067] S3: Hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, and hydroquinone were added sequentially to deionized water to obtain a basic additive stock solution; sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, and composite amine mixture were added sequentially to obtain a composite agent stock solution, wherein the composite amine mixture was obtained by premixing cyclohexylamine, diethylaminoethanol, and morpholine in a mass ratio of 1.2:2:1.5; the mass ratios of sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution, hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide, hydroquinone, and composite amine mixture were 25:15:10:0.8:6:0.5:18, respectively; after stirring evenly, the pH value was adjusted to 9 with sodium hydroxide solution to obtain a high-efficiency boiler scale and corrosion inhibitor composite agent.

[0068] Comparative Example 1

[0069] This comparative example provides a high-efficiency boiler scale and corrosion inhibitor composite agent. The difference from Example 1 is that a sulfonated polycarboxylic acid copolymer solution is used instead of a polyether graft copolymer solution. Other operating steps and process parameters are exactly the same as in Example 1.

[0070] Comparative Example 2

[0071] This comparative example provides a high-efficiency boiler scale and corrosion inhibitor composite agent. The difference from Example 1 is that a polyether graft copolymer solution is used instead of a sulfonated polycarboxylic acid copolymer solution. Other operating steps and process parameters are exactly the same as in Example 1.

[0072] Comparative Example 3

[0073] This comparative example provides a high-efficiency boiler scale and corrosion inhibitor composite agent. The difference between this example and Example 1 is that hydroxyethylidene diphosphonic acid is not added, while the other operating steps and process parameters are exactly the same as in Example 1.

[0074] Comparative Example 4

[0075] This comparative example provides a high-efficiency boiler scale and corrosion inhibitor composite agent. The difference between this example and Example 1 is that hydroquinone is not added, while the other operating steps and process parameters are exactly the same as in Example 1.

[0076] The performance of the high-efficiency boiler scale and corrosion inhibitor composite agents prepared in Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0077] The scale inhibition performance of the samples was tested according to GB / T16632-2008;

[0078] According to GB / T18175-2014, the corrosion inhibition performance of the test samples was tested using standard steel test pieces;

[0079] A dissolved oxygen meter is used to test the concentration of dissolved oxygen in a water sample and to detect the sample's deoxygenation performance.

[0080] The test results are shown in Table 1.

[0081] Table 1 Performance test results of the high-efficiency boiler scale and corrosion inhibitor composite agents prepared in Examples 1-4 and Comparative Examples 1-4

[0082]

[0083] As shown in Table 1, the test results of Example 1 and Comparative Example 1 reveal that when the sulfonated polycarboxylic acid copolymer solution is used instead of the polyether graft copolymer solution, the system contains only the sulfonated polycarboxylic acid copolymer. This results in insufficient macromolecular dispersion and coating, leading to easier local accumulation of scaling and corrosion products, thus increasing the corrosion rate. However, in static tests, the scale inhibition rate remained high due to the increased amount of sulfonated polycarboxylic acid copolymer; the dissolved oxygen concentration showed little change because its oxygen removal components and synergistic mechanism remained unchanged.

[0084] As can be seen from the test results of Example 1 and Comparative Example 2 in Table 1, replacing the sulfonated polycarboxylic acid copolymer solution with a polyether graft copolymer solution caused the system to lose its source inhibition function, making it unable to effectively intervene in the crystal nucleation stage, and only able to treat the dispersed system of already formed particles; its scale inhibition rate decreased because the lack of source inhibition made it easier for scale-forming ions to form crystal nuclei, increasing the number of already formed microcrystals beyond the range that could be controlled by dispersion alone, resulting in large-scale scaling; the corrosion rate deteriorated because a large amount of scale quickly adhered to the metal surface, triggering under-deposit corrosion; while the deoxygenation performance did not change much because its related components remained intact.

[0085] As shown in Table 1, the test results of Example 1 and Comparative Example 3 reveal that without the addition of hydroxyethylidene diphosphonic acid (HEDTA), the scale inhibition system loses its small-molecule synergistic component, making it difficult to form a complementary synergistic scale inhibition network between the polymer and small molecules, and instead relying solely on the macromolecular polymer system. The decrease in scale inhibition rate is due to the lack of HEDTA's chelation of calcium ions and effective adsorption to microcrystalline lattice points, thus disrupting its synergistic effect with the sulfonated polycarboxylic acid copolymer at different action sites. Simultaneously, the increased corrosion rate is due to both the increased scaling tendency raising the risk of localized corrosion and the fact that HEDTA itself possesses a certain corrosion inhibition capacity; its absence weakens the overall stability of the corrosion inhibition system. The deoxygenation component is not affected, therefore the dissolved oxygen concentration does not change significantly.

[0086] As can be seen from the test results of Example 1 and Comparative Example 4 in Table 1, the absence of hydroquinone caused the deoxygenation system to lose its synergistic promoting component. At medium and low temperatures, the reaction rate of carbazide decreased, and dissolved oxygen was difficult to reduce in time. Long-term high dissolved oxygen levels caused oxygen corrosion to intensify, thereby increasing the corrosion rate.

[0087] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a high-efficiency boiler scale and corrosion inhibitor composite agent, characterized in that, The preparation method includes: S1: Isopropanol and deionized water are added to a reaction vessel, and the pH value is adjusted with sulfuric acid before heating to obtain the reaction base liquid; maleic anhydride is dispersed in isopropanol to obtain a slurry; acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid are dispersed in deionized water to form a monomer solution; ammonium persulfate is dispersed in deionized water to form a first initiator solution; simultaneously, the slurry, monomer solution and first initiator solution are added dropwise to the reaction base liquid to obtain reaction solution A; after the addition is completed, the temperature is maintained, and after cooling, the pH value is adjusted with sodium hydroxide solution to obtain a sulfonated polycarboxylic acid copolymer solution; S2: Acrylic acid and vinylpyrrolidone are dispersed in deionized water to form a main chain monomer solution; polyethylene glycol methacrylate is dispersed in deionized water to form a side chain monomer solution; ammonium persulfate is dispersed in deionized water to form a second initiator solution; deionized water is added to a reaction vessel, and after heating, the main chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution B. The reaction is stirred, and the side chain monomer solution and the second initiator solution are added dropwise to obtain reaction solution C. The reaction is kept at a constant temperature, and after cooling, the pH value is adjusted with sodium hydroxide solution to obtain a polyether graft copolymer solution. S3: Hydroxyethylidene diphosphonic acid, methylbenzotriazole, carbazide and hydroquinone are added sequentially to deionized water to obtain the basic additive stock solution; sulfonated polycarboxylic acid copolymer solution, polyether graft copolymer solution and composite amine mixture are added sequentially to obtain the composite agent stock solution. After stirring evenly, the pH value is adjusted with sodium hydroxide solution to obtain the high-efficiency boiler scale and corrosion inhibitor composite agent.

2. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S1: The amount of isopropanol used in the reaction substrate accounts for 40-60% of the total amount of isopropanol used in S1. The mass ratio of isopropanol to deionized water in the reaction substrate is 1:(15-25).

3. The preparation method of the high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S1: The mass ratio of maleic anhydride to isopropanol in the slurry is 1:(1.5-2.5).

4. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S1: The total mass ratio of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid in the monomer solution to the mass ratio of deionized water is 1:(1.2-1.5).

5. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S1: The molar ratio of acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid in the reaction solution A is (3.0-5.0):(2.0-4.0):1.0; The total molar ratio of ammonium persulfate to monomers acrylic acid, maleic anhydride and 2-acrylamido-2-methylpropanesulfonic acid in the reaction solution A is 1:(30-60).

6. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S2: The mass concentration of the main chain monomer solution is 50-65%; The mass concentration of the side-chain monomer solution is 50-70%; The amount of ammonium persulfate in reaction solution B accounts for 30-40% of the total amount of ammonium persulfate in S2.

7. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S2: The molar ratio of acrylic acid, vinylpyrrolidone, and polyethylene glycol methacrylate is (3.0-6.0):(1.0-2.0):1.0; The total molar ratio of ammonium persulfate in S2 to the total molar ratio of monomers acrylic acid, vinyl pyrrolidone, and polyethylene glycol methacrylate is 1:(150-250).

8. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S3: The mass ratio of cyclohexylamine, diethylaminoethanol and morpholine in the compound amine mixture is (0.8-1.2):2:(1-1.5).

9. The preparation method of a high-efficiency boiler scale and corrosion inhibitor composite agent according to claim 1, characterized in that, In S3: The mass ratio of the sulfonated polycarboxylic acid copolymer solution, the polyether graft copolymer solution, the hydroxyethylidene diphosphonic acid, the methylbenzotriazole, the carbazide, the hydroquinone and the complex amine mixture is (15-25):(15-25):(5-10):(0.8-2):(3-6):(0.5-1):(8-18).

10. A high-efficiency boiler scale and corrosion inhibitor composite agent prepared by the preparation method according to any one of claims 1-9.

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