Composite reagent for boiler as well as preparation method and application of composite reagent

Abstract

The invention relates to the technical field of water treatment, and particularly provides a composite agent for a boiler and a preparation method and application thereof.The composite agent for the boiler is prepared from, by mass, 20-25 parts of a pH regulator, 15-18 parts of a dispersing agent, 12-15 parts of a protective film precursor, 10-12 parts of a nanometer corrosion inhibitor and 8-10 parts of a deoxidant; 5-7 parts of a stabilizer; 3-6 parts of an anti-settling agent; 2-4 parts of a pH buffer solution; and 40-55 parts of a matrix. The composite agent for the boiler can adapt to different water quality environments, dynamic adjustment is carried out according to water quality changes, and a protective layer is formed on the surface of the boiler, so that the corrosion and scaling problems of the boiler are effectively reduced, and the service life of the boiler is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of water treatment, and in particular to a composite agent for boilers and a preparation method and application thereof. Background Art

[0002] Boilers play a very important role in industrial production and are widely used in thermal power plants, ships, locomotives, steel and industrial and mining enterprises. During the use of the boiler, after the feed water containing impurities enters the boiler, due to the high concentration of scale components such as calcium and magnesium in the water, solid sediments are precipitated after continuous evaporation and concentration to reach saturation. These precipitates firmly adhere to the heating surface to form scale. When the scale components such as calcium and magnesium entering the boiler adhere to the heat transfer surface, it will cause heat transfer obstacles. This heat transfer obstacle will become the cause of steel expansion, bending, cracking and reduced thermal efficiency caused by overheating, and may also cause the boiler steel plate and pipeline to be burned due to overheating. Therefore, once the heating surface in the furnace is corroded and scaled, its service life will be significantly shortened, energy consumption will increase, and even boiler explosion accidents may occur. In order to prevent corrosion and scaling of the boiler, the feed water of the boiler must be treated.

[0003] Therefore, in order to prevent corrosion and scaling of the boiler, an appropriate amount of reagents are usually added to the boiler water to achieve the purpose of preventing corrosion and scaling of the boiler. Among the commonly used boiler reagents, phosphorus-containing reagents are usually used, and their corrosion and scaling effects are often not ideal. In addition, the presence of phosphorus will cause eutrophication of the water body, which is not friendly to the environment. Therefore, it is urgent to provide a composite reagent for boilers with better treatment effect and environmental friendliness. Summary of the invention

[0004] The present invention aims to solve at least one of the above technical problems.

[0005] To achieve the first object of the present invention, the present invention provides a composite agent for a boiler, which comprises, by weight: 20-25 parts of a pH regulator, 15-18 parts of a dispersant, 12-15 parts of a protective film precursor, 10-12 parts of a nano-corrosion inhibitor, 8-10 parts of an oxygen scavenger, 5-7 parts of a stabilizer, 3-6 parts of an anti-settling agent, 2-4 parts of a pH buffer, and 40-55 parts of a matrix. The preparation method of the composite agent for a boiler comprises:

[0006] S100, adding the nano corrosion inhibitor to part of the matrix and dispersing it evenly to obtain a nano corrosion inhibitor solution;

[0007] S200, adding the deoxidizer and the anti-settling agent to the remaining matrix and dispersing them evenly to obtain a solution of the deoxidizer and the anti-settling agent;

[0008] S300, adding a pH regulator and a dispersant to a nano corrosion inhibitor solution, performing a first stirring treatment, and adding a protective film precursor during the first stirring treatment to obtain a mixed solution;

[0009] S400, adding the solution of the deoxidizer and the anti-settling agent dropwise to the mixed solution for a second stirring treatment, adding a stabilizer during the second stirring treatment, and then adding a pH buffer solution to adjust the pH, to obtain a composite agent for a boiler;

[0010] The pH adjuster includes microcapsules containing a weak acid-weak base copolymer.

[0011] In any of the above technical solutions, the weak acid-weak base copolymer includes polyacrylic acid-polymethyl methacrylate copolymer.

[0012] In any of the above technical solutions, the dispersant includes at least one of polymaleic acid, polyacrylic acid and polyaspartic acid; and / or the protective film precursor includes one of polyether modified silane or sodium molybdate; and / or the nano corrosion inhibitor includes at least one of nano graphene oxide, nano silicon dioxide, nano ammonium molybdate, nano zinc phosphate and nano aluminum oxide.

[0013] To achieve the second object of the present invention, the present invention provides a method for preparing a composite agent for a boiler, which is used to prepare a composite agent for a boiler as described in any one of the above technical solutions, and the preparation method comprises:

[0014] S100, adding the nano corrosion inhibitor to part of the matrix and dispersing it evenly to obtain a nano corrosion inhibitor solution;

[0015] S200, adding the deoxidizer and the anti-settling agent to the remaining matrix and dispersing them evenly to obtain a solution of the deoxidizer and the anti-settling agent;

[0016] S300, adding a pH regulator and a dispersant to a nano corrosion inhibitor solution, performing a first stirring treatment, and adding a protective film precursor during the first stirring treatment to obtain a mixed solution;

[0017] S400, adding the solution of the deoxidizer and the anti-settling agent dropwise to the mixed solution for a second stirring treatment, adding a stabilizer during the second stirring treatment, and then adding a pH buffer solution to adjust the pH, to obtain a composite agent for a boiler;

[0018] The pH adjuster includes a microcapsule emulsion containing a weak acid-weak base copolymer.

[0019] In any of the above technical solutions, the method for preparing the microcapsule emulsion containing the weak acid-weak base copolymer comprises:

[0020] S310, adding the weak acid-weak base copolymer to an organic solvent, and performing ultrasonic dispersion treatment to obtain a weak acid-weak base copolymer solution;

[0021] S320, adding the coating material and the emulsifier into deionized water and dispersing them evenly to obtain a coating material solution;

[0022] S330, dropping the weak acid-weak base copolymer solution into the coating material solution, performing a third stirring treatment, and obtaining microcapsules containing the weak acid-weak base copolymer;

[0023] The weak acid-weak base copolymer includes a copolymer of polyacrylic acid and polymethyl methacrylate; and the coating material includes any one of polyvinyl alcohol, gelatin and porous cyclodextrin.

[0024] In any of the above technical solutions, in S310, the mass ratio of the weak acid-weak base copolymer to the organic solvent is (0.1-0.3):1; and / or in S320, the mass ratio of the coating material to deionized water is (0.01-0.1):1; and / or in S320, the mass ratio of the emulsifier to the weak acid-weak base copolymer is (0.05-0.2):1.

[0025] In any of the above technical solutions, the preparation method of the polyacrylic acid-polymethyl methacrylate copolymer comprises:

[0026] S311, adding acrylic acid and methacrylic acid into an ethanol aqueous solution, stirring evenly, to obtain an acrylic acid-methacrylic acid solution;

[0027] S312, dripping the initiator solution into the acrylic acid-methacrylic acid solution, performing a fourth stirring treatment, and adding a crosslinking agent during the fourth stirring treatment to obtain a polyacrylic acid-polymethyl methacrylate copolymer.

[0028] In any of the above technical solutions, in S311, the mass ratio of acrylic acid, methacrylic acid and ethanol aqueous solution is 1:(1-1.5):1.2; and / or in S312, the temperature of the fourth stirring treatment is 60-70°C; and / or in S312, the rotation speed of the fourth stirring treatment is 300-500rpm.

[0029] In any of the above technical solutions, in S300, the temperature of the first stirring treatment is 40-50°C; and / or in S300, the time of the first stirring treatment is 55-70min; and / or in S400, the temperature of the second stirring treatment is 45-50°C; and / or in S400, the time of the second stirring treatment is 65-70min.

[0030] To achieve the third purpose of the present invention, the present invention provides an application of a composite agent for a boiler, and the composite agent for a boiler is used for boiler water treatment.

[0031] After adopting the technical solution of the present invention, the technical effects that can be achieved are as follows:

[0032] 1. By adopting the composite agent for boilers of the present invention, it is possible to adapt to different water quality environments, dynamically adjust according to water quality changes, and form a protective layer on the surface of the boiler, thereby effectively reducing the corrosion and scaling problems of the boiler, thereby increasing the service life of the boiler;

[0033] 2. The preparation method of the composite agent for boilers of the present invention adopts a process of step-by-step dissolution, uniform dispersion, and stage-by-stage stirring to ensure that each functional component can be fully dissolved, uniformly distributed, and form a stable composite system;

[0034] 3. Nano corrosion inhibitors have smaller particle sizes and higher specific surface areas, and can penetrate into the metal surface of boiler equipment in a shorter time, further forming a uniform and stable protective film, providing long-term protection for boiler equipment. Even in high temperature and high pressure environments, nano corrosion inhibitors can still have a good anti-corrosion effect;

[0035] 4. pH regulators are mainly used to control the pH of boiler water. When the acidity or alkalinity of boiler water fluctuates, the pH can be adjusted quickly to inhibit corrosion of metal surfaces and prevent acidic or alkaline water from affecting boiler equipment, thereby avoiding corrosion or scaling of boiler equipment. DETAILED DESCRIPTION

[0036] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0038] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below.

[0039] In the related technology, since various substances related to scaling and corrosion are inevitably mixed into the boiler during long-term operation, it brings serious safety hazards to the boiler. Among them, hardness components, oxygen and carbon dioxide are the main causes of corrosion and scaling.

[0040] In view of this, an embodiment of the present invention provides a composite agent for boilers and a preparation method and application thereof. By adjusting the ingredients of the composite agent for boilers and selecting a suitable preparation method according to the ingredients, a composite agent for boilers with better treatment effect and environmental friendliness can be obtained.

[0041] Specifically, an embodiment of the present invention provides a composite agent for a boiler, which includes, by mass: pH adjuster: 20-25 parts, dispersant: 15-18 parts, protective film precursor: 12-15 parts, nano corrosion inhibitor: 10-12 parts, deoxidizer: 8-10 parts; stabilizer: 5-7 parts; anti-settling agent: 3-6 parts; pH buffer: 2-4 parts; matrix: 40-55 parts.

[0042] Preferably, the composite agent for boilers of the present invention comprises a pH regulator, a dispersant, a protective film precursor, a nano-corrosion inhibitor, an oxygen scavenger, a stabilizer, an anti-settling agent, a pH buffer and a matrix. The pH regulator is mainly used to control the pH of boiler water. When the acid-base fluctuation occurs in the boiler water quality, the pH can be quickly adjusted to inhibit the corrosion of the metal surface and prevent the acidic or alkaline water quality from affecting the boiler equipment, thereby avoiding the problem of corrosion or scaling of the boiler equipment; the dispersant can effectively disperse the calcium, magnesium and other ions in the boiler water and the solid particles in the water to prevent them from settling on the inner wall of the boiler, thereby effectively reducing scaling, thereby improving the heat exchange efficiency of the boiler and reducing energy consumption; the protective The membrane precursor can form a protective film on the metal surface of the inner wall of the boiler, reduce the direct contact between corrosive substances and the metal surface, play an isolating role, and effectively prevent metal oxidation and corrosion, and improve the corrosion resistance and service life of boiler equipment; the nano corrosion inhibitor has a smaller particle size and a higher specific surface area, and can penetrate into the metal surface of the boiler equipment in a shorter time, further forming a uniform and stable protective film, providing long-term protection for the boiler equipment. Even in a high temperature and high pressure environment, the nano corrosion inhibitor can still have a good anti-corrosion effect; the deoxidizer can effectively remove the dissolved oxygen in the boiler water, reduce the oxidative corrosion caused by dissolved oxygen, and, Deoxidizers can also prevent boiler equipment from oxidizing under high temperature and high pressure, further avoiding oxidation corrosion of boiler equipment; stabilizers are used to improve the stability of composite agents for boilers, prevent the decomposition of their active ingredients during storage and transportation, and avoid stratification of composite agents for boilers, thereby extending the shelf life of composite agents for boilers and ensuring that the agents are uniform and stable during use and have a good treatment effect; anti-sedimentation agents can effectively prevent particulate matter in composite agents from settling or aggregating during storage and transportation, so that the agents remain dispersed and uniform during use, thereby improving the stability of the agents; pH buffers are used to adjust the The pH value is adjusted to a value between 8.5 and 9.5, so that the pH value is stabilized at an optimal state of 8.5-9.5. Within this pH range, the composite agent for boilers can inhibit corrosion of metal surfaces to the greatest extent, especially metals such as iron and copper, which helps to improve the treatment effect of the agent. The matrix is ​​used as a carrier of the composite agent for boilers, preferably deionized water, which can effectively dissolve the active ingredients of the composite agent for boilers and ensure that these active ingredients will not decompose or become ineffective. By adopting the composite agent for boilers of the present invention, it is possible to adapt to different water quality environments, dynamically adjust to changes in water quality, and form a protective layer on the surface of the boiler, thereby effectively reducing the corrosion and scaling problems of the boiler, thereby increasing the service life of the boiler.

[0043] Furthermore, the preparation method of the composite agent for boiler includes:

[0044] S100, adding the nano corrosion inhibitor to part of the matrix and dispersing it evenly to obtain a nano corrosion inhibitor solution;

[0045] S200, adding the deoxidizer and the anti-settling agent to the remaining matrix and dispersing them evenly to obtain a solution of the deoxidizer and the anti-settling agent;

[0046] S300, adding a pH regulator and a dispersant to a nano corrosion inhibitor solution, performing a first stirring treatment, and adding a protective film precursor during the first stirring treatment to obtain a mixed solution;

[0047] S400, adding the solution of deoxidizer and anti-settling agent dropwise into the mixed solution for a second stirring treatment, adding a stabilizer during the second stirring treatment, and then adding a pH buffer solution to adjust the pH, thereby obtaining a composite agent for a boiler.

[0048] Preferably, the preparation method of the composite agent for boilers of the present invention adopts a process of step-by-step dissolution, uniform dispersion, and staged stirring to ensure that each functional component can be fully dissolved and evenly distributed to form a stable composite system; first, the matrix is ​​divided into two parts, wherein the mass of the first matrix is ​​two-thirds of the total mass of the matrix, and the mass of the second matrix is ​​one-third of the total mass of the matrix; the nano corrosion inhibitor is added to the first matrix. Since the particle size of the nano corrosion inhibitor is small and easy to agglomerate, if it is directly added to the agent system, it may cause uneven dispersion, thereby reducing its corrosion inhibition effect. Therefore, the nano corrosion inhibitor is first evenly dispersed in the first matrix, which helps to prevent particle agglomeration, improve its stability and dispersion, and ensure uniform mixing of subsequent components. It is preferred to use a high-speed shear emulsifier to disperse at a speed of 1700-2100rpm for 35min. After the nano corrosion inhibitor is evenly dispersed, a dense protective layer can be formed on the metal surface, reducing the erosion of corrosive substances and improving the anti-corrosion performance of the boiler system.

[0049] Preferably, the deoxidizer and the anti-settling agent are added to the second matrix. The uniform dispersion of the deoxidizer and the anti-settling agent makes it easier to evenly distribute them during subsequent mixing, reduces the problems of component stratification and sedimentation during the storage of the agent, prolongs the service life of the agent, enhances its reaction rate with dissolved oxygen, and improves the deoxidation effect. Preferably, the agent is dispersed at a rotation speed of 450-650rpm for 30min.

[0050] Preferably, a pH adjuster and a dispersant are added to the nano corrosion inhibitor solution in sequence, which can make the pH adjuster more evenly distributed and enhance the dispersing effect of the dispersant. The protective film precursor is added during the first stirring treatment, and the protective film precursor is evenly dispersed under the first stirring treatment, making it easier to form a dense protective film on the metal surface, thereby improving the corrosion resistance of the boiler equipment. The temperature of the first stirring treatment is preferably 40-50°C, and the time is preferably 55-70min, which can enable the protective film precursor and the nano corrosion inhibitor to form a certain degree of pre-polymerization, which is conducive to the subsequent formation of a protective film on the metal surface of the boiler equipment.

[0051] Preferably, the solution of the deoxidizer and the anti-settling agent is added dropwise to the mixed solution, and is fully stirred through a second stirring treatment, and a stabilizer is added during the second stirring treatment. The temperature of the second stirring treatment is preferably 45-50°C, and the time is preferably 65-70min, which can enable each component to achieve an optimal uniform distribution state on a microscopic scale, and then a pH buffer is added to further adjust the pH of the agent to 8.5-9.5 to ensure the stability of the entire system and the durability of the agent; after adding the pH buffer, it is further necessary to use a microporous filtration membrane to filter and remove impurities that are not completely dissolved.

[0052] Furthermore, the dispersant includes at least one of polymaleic acid, polyacrylic acid and polyaspartic acid. The dispersant is mainly used to prevent the agglomeration of solid particles, maintain the uniform distribution of the agent system, and improve the stability of the effective ingredients. Among them, polymaleic acid (HPMA) has excellent high temperature resistance and is particularly suitable for high temperature boiler environments. HPMA can chelate calcium and magnesium ions to prevent scale deposition and improve the heat exchange efficiency of the boiler; polyacrylic acid (PAA) improves the dispersion stability of the nano corrosion inhibitor through electrostatic repulsion and prevents it from settling or agglomerating in the agent solution, and PAA has a certain corrosion inhibition effect and can form a protective layer with metal ions; polyaspartic acid (PASP) is biodegradable, which can reduce the impact on the environment, can chelate calcium and magnesium ions well, and can reduce the scaling tendency of boiler water and improve the boiler water treatment efficiency.

[0053] Preferably, the protective film precursor includes one of polyether-modified silane or sodium molybdate, and the protective film precursor forms a dense passivation film on the metal surface of the boiler equipment, reduces the erosion of corrosive substances, and improves the corrosion resistance of the metal. Among them, polyether-modified silane can enhance the adhesion of the agent to the metal surface of the boiler, thereby reducing the direct contact between water and metal, thereby reducing the risk of oxygen corrosion and acid-base corrosion; sodium molybdate is a cathodic corrosion inhibitor that can form a molybdate protective film on the metal surface, which can be applied to boiler systems under different water quality conditions, provide a stable protective effect, effectively inhibit redox reactions, and reduce corrosion rates.

[0054] Preferably, the nano corrosion inhibitor includes at least one of nano graphene oxide, nano silicon dioxide, nano ammonium molybdate and nano aluminum oxide. The nano corrosion inhibitor improves the corrosion resistance of the metal surface and reduces the erosion of the corrosive medium. At the same time, it forms a protective film on the metal surface of the boiler equipment together with the protective film precursor. Among them, nano graphene oxide has high strength and high chemical stability, and can form a protective barrier on the metal surface to prevent the diffusion of oxygen and water, thereby reducing the corrosion rate; nano silicon dioxide enhances the adhesion of the corrosion inhibitor on the metal surface through physical adsorption, and improves the stability and durability of the protective film; nano ammonium molybdate has excellent oxidation corrosion inhibition performance, can improve the corrosion resistance of the metal, and is particularly suitable for high temperature and high pressure boilers; nano aluminum oxide improves the corrosion resistance of the metal surface and the anti-sedimentation performance of the agent through the nanoparticle effect, so that it is evenly distributed in the water phase and improves its utilization efficiency.

[0055] Furthermore, the deoxidizer includes at least one of sodium sulfite, hydroxylamine and sodium isoascorbate. The deoxidizer is mainly used to remove dissolved oxygen in boiler water to prevent oxygen corrosion. Sodium sulfite can efficiently remove dissolved oxygen at high temperature and reduce the occurrence of oxygen corrosion; hydroxylamine has strong reducing properties and is suitable for different boiler operating conditions; sodium isoascorbate is an environmentally friendly deoxidizer, which has a certain corrosion inhibition effect while having a deoxidizing effect; the stabilizer includes at least one of polyvinyl pyrrolidone, trisodium citrate and EDTA. The stabilizer maintains the stability of the agent. Polyvinyl pyrrolidone (PVP) can enhance the solubility and dispersibility of the agent and improve the uniformity of the system; trisodium citrate (TSC) can stabilize metal ions to prevent the agent from failing due to precipitation; EDTA (ethylenediaminetetraacetic acid) can effectively complex Ca in water 2+ Mg 2+ , thereby reducing scale formation and improving the stability of the corrosion inhibitor; the anti-settling agent includes at least one of silica, kaolin nanoparticles and carbon nanotubes. The function of the anti-settling agent is to prevent solid particles from settling and maintain the uniformity of the reagent system. Silica can improve the colloidal stability of the system and prevent particles from agglomerating or precipitating; kaolin nanoparticles have good dispersibility and can improve the stability and long-term storage capacity of the reagent; carbon nanotubes (CNTs) can enhance the rheological properties of the reagent and make the reagent evenly distributed during the boiler water treatment process, thereby improving the efficacy; the pH buffer solution includes at least one of sodium bicarbonate solution, sodium hydroxide solution and boric acid solution. The pH buffer solution is used to adjust the pH of the composite reagent for the boiler to an appropriate range. The sodium bicarbonate solution has a strong buffering capacity and is suitable for neutral to weakly alkaline systems; the sodium hydroxide solution adjusts the pH to weakly alkaline to prevent acidic corrosion; the boric acid solution has a buffering effect and can synergistically prevent corrosion and improve the stability of the reagent.

[0056] Preferably, the pH regulator includes microcapsules containing weak acid-weak base copolymers. The weak acid-weak base copolymers contain both weak acidic groups and weak basic groups. These groups will be ionized or protonated under different pH conditions, showing zwitterionic properties. The weak acid-weak base copolymers have pH buffering capacity and can adjust and stabilize the pH value of the boiler water system. In an acidic environment, the weak basic groups in the weak acid-weak base copolymers can absorb excess H + , inhibiting the further decrease of pH; in an alkaline environment, the weak acid groups in the weak acid-weak base copolymer can release H + , neutralize OH - , inhibiting the further increase of pH; in a neutral environment, the weak acid-weak base copolymer maintains pH stability through dynamic equilibrium; when the pH changes, the ionization state and charge distribution of the weak acid-weak base copolymer will quickly adjust to adapt to the new pH environment, allowing the weak acid-weak base copolymer to maintain stable performance in the pH fluctuations of the boiler water system.

[0057] Furthermore, the preparation method of the microcapsule emulsion containing the weak acid-weak base copolymer comprises:

[0058] S310, adding the weak acid-weak base copolymer to an organic solvent, and performing ultrasonic dispersion treatment to obtain a weak acid-weak base copolymer solution;

[0059] S320, adding the coating material and the emulsifier into deionized water and dispersing them evenly to obtain a coating material solution;

[0060] S330, dripping the weak acid-weak base copolymer solution into the coating material solution, performing a third stirring treatment, and obtaining microcapsules containing the weak acid-weak base copolymer.

[0061] Preferably, the solubility and dispersibility of the weak acid-weak base copolymer are low, and direct addition to the aqueous phase may lead to agglomeration or uneven distribution. Therefore, an organic solvent such as ethanol, ethyl acetate or N,N-dimethylformamide (DMF) is used as a dispersion medium to uniformly dissolve the weak acid-weak base copolymer, and an ultrasonic dispersion method is used to improve the uniformity. Under the action of ultrasound, the particles of the weak acid-weak base copolymer are uniformly dispersed into nanometer or micrometer levels to improve the subsequent emulsification efficiency. In addition, ultrasonic treatment can make its interface more active and improve the compatibility with the aqueous phase in the subsequent emulsification process. The mass ratio of the weak acid-weak base copolymer to the organic solvent is (0.1-0.3): 1, which can ensure the best dispersion effect and form a stable weak acid-weak base copolymer solution.

[0062] Preferably, the coating material is used as the shell layer of the microcapsule and is added to deionized water together with an emulsifier. The emulsifier can be Tween 80, SPAN60, etc., as long as it can reduce the interfacial tension, stabilize the oil-water system, and prevent the microcapsule from agglomerating. No specific limitation is made here; the coating material includes any one of polyvinyl alcohol, gelatin and porous cyclodextrin. Polyvinyl alcohol (PVA) can form a dense water-soluble protective film to slowly release the microcapsules in water; gelatin can form pH-responsive microcapsules, which are suitable for the controlled release of boiler agents; porous cyclodextrin can increase the loading amount of the agent and has excellent sustained-release properties; the mass ratio of the coating material to deionized water is (0.01-0.1):1, and the mass ratio of the emulsifier to the weak acid-weak base copolymer is (0.05-0.2):1, which can ensure that the microcapsule shell is uniform and has good stability and sustained-release properties.

[0063] Furthermore, the weak acid-weak base copolymer solution is dripped into the coating material solution at a uniform speed, and a third stirring treatment is performed to ensure that the particle size distribution of the formed microcapsules is uniform, so as to improve the sustained release performance and stability of the drug; through the third stirring treatment, the interaction balance between the water phase and the oil phase is promoted, the morphology of the microcapsules is more regular, and the quality of the finished product is improved; the third stirring treatment is preferably performed at a speed of 2000-4000rpm for 10-30min.

[0064] Preferably, the weak acid-weak base copolymer preferably adopts polyacrylic acid-polymethyl methacrylate copolymer. Polyacrylic acid (PAA) is a typical weak acid polymer. In a low pH, i.e., acidic environment, it is hydrophobic. In a high pH, ​​i.e., alkaline environment, its carboxyl group is converted into carboxylate and becomes hydrophilic. This property makes PAA highly sensitive to pH changes. At the same time, PAA is resistant to high temperature, acid and alkali, suitable for the complex chemical environment of the boiler system, and can maintain its molecular structure stable under extreme conditions. The carboxyl group of PAA can react with Ca 2+ Mg 2+ It can chelate hardness ions, reduce the formation of calcium carbonate, calcium sulfate and other deposits, avoid the formation of boiler scale, and its reversibility under pH changes enables it to still play an effective role under high temperature conditions; polymethyl methacrylate (PMMA) is a hydrophobic polymer that can provide a stable skeleton structure and maintain the overall shape of the material when the pH changes, even under high temperature and high pressure conditions. When PAA and PMMA are copolymerized, a cross-linked network structure is formed. After partial dissociation of PAA, a stable complex can be formed and a protective film can be formed on the metal surface, thereby reducing the corrosion risk of the metal inside the boiler. The hydrophobic structure of the PMMA part provides a barrier effect in the water environment, further preventing corrosive substances such as Cl-, SO4 2- etc. to metal corrosion, through copolymerization, the pH responsiveness of PAA and the durability of PMMA are combined to form a controlled release system, so that the drug can show adjustable activity in different environments.

[0065] Furthermore, polyacrylic acid-polymethyl methacrylate copolymer is prepared into microcapsules. In an acidic environment, PAA is in a hydrophobic state, the microcapsule wall material is closed, and the agent is not easily released; in an alkaline environment, the PAA part swells, so that the active substances in the microcapsule are gradually released, realizing intelligent controlled release; the PMMA part provides mechanical strength to ensure that the microcapsule does not break or degrade in a high temperature environment and maintains a stable release mechanism; during the initial operation of the boiler, the PAA part is in a hydrophobic state, and the release rate of active ingredients such as corrosion inhibitors and dispersants is low, ensuring that the boiler will not be overdosed in the initial stage; during the continuous operation of the boiler, the PAA part begins to partially dissociate, the swelling degree increases, and the agent is gradually released, thereby improving the ability to control the water quality in the boiler.

[0066] Furthermore, the preparation method of the polyacrylic acid-polymethyl methacrylate copolymer comprises:

[0067] S311, adding acrylic acid and methacrylic acid into an ethanol aqueous solution, stirring evenly, to obtain an acrylic acid-methacrylic acid solution;

[0068] S312, dripping the initiator solution into the acrylic acid-methacrylic acid solution, performing a fourth stirring treatment, and adding a crosslinking agent during the fourth stirring treatment to obtain a polyacrylic acid-polymethyl methacrylate copolymer.

[0069] Preferably, the ethanol aqueous solution can effectively dissolve acrylic acid and methacrylic acid and promote their uniform dispersion in the aqueous phase to ensure sufficient reaction between acrylic acid and methacrylic acid. The mass ratio of acrylic acid, methacrylic acid and ethanol aqueous solution is 1:(1-1.5):1.2, which can maintain good solubility while avoiding excessive solvent concentration that leads to excessive dilution of the reaction system and affects the efficiency of the copolymerization reaction.

[0070] Preferably, the introduction of an initiator and a cross-linking agent allows acrylic acid and methacrylic acid to undergo free radical polymerization and cross-linking reactions under appropriate temperature conditions. The initiator promotes the polymerization reaction of acrylic acid and methacrylic acid by generating free radicals to generate polymer chains. The initiator is preferably an ammonium persulfate solution (APS), which is prepared into a solution of appropriate concentration by dissolving ammonium persulfate in deionized water. Nitrogen needs to be introduced during the preparation process to remove dissolved oxygen to prevent the initiator from failing. The cross-linking agent is preferably N, N'-methylenebisacrylamide, which forms a three-dimensional cross-linked structure between the polymer chains through copolymerization and cross-linking reactions, thereby increasing the thermal stability of the polymer and ultimately forming a polymer with high stability.

[0071] Preferably, in S312, after adding the cross-linking agent, an antioxidant such as vitamin C, BHT (butylated hydroxytoluene) or the like is further added to terminate the free radical reaction, and then filtered to obtain a polyacrylic acid-polymethyl methacrylate copolymer.

[0072] Preferably, the temperature of the fourth stirring treatment is preferably 60-70° C., and the rotation speed is preferably 300-500 rpm, which can ensure that the initiator is fully activated and promotes the polymerization reaction, ensure that the components are evenly distributed during the polymerization process, and effectively avoid excessive particles or precipitation.

[0073] Embodiment 1

[0074] The present embodiment provides a composite agent for boilers, which comprises, by weight: 20 parts of microcapsules containing weak acid-weak base copolymers, 15 parts of polyacrylic acid, 12 parts of sodium molybdate, 10 parts of nano-silicon dioxide, 8 parts of hydroxylamine, 5 parts of trisodium citrate, 3 parts of kaolin nanoparticles, 2 parts of sodium hydroxide solution, and 40 parts of deionized water. The preparation method of the composite agent for boilers comprises:

[0075] S100, dividing the matrix into two parts, the mass of the first part of the matrix is ​​two-thirds of the total mass of the matrix, and the mass of the second part of the matrix is ​​one-third of the total mass of the matrix, adding nano-silicon dioxide to the first part of the matrix and dispersing it at a speed of 1700 rpm for 35 minutes to obtain a nano-corrosion inhibitor solution;

[0076] S200, adding hydroxylamine and kaolin nanoparticles to the second matrix and dispersing at a rotation speed of 450 rpm for 30 minutes to obtain a solution of deoxidizer and anti-settling agent;

[0077] S300, adding microcapsules containing weak acid-weak base copolymer and polyacrylic acid to the nano corrosion inhibitor solution, performing a first stirring treatment at 40° C. for 70 minutes, and adding sodium molybdate during the first stirring treatment to obtain a mixed solution;

[0078] S400, adding the solution of deoxidizer and anti-settling agent dropwise to the mixed solution and performing a second stirring treatment at 45° C. for 70 minutes, adding trisodium citrate during the second stirring treatment, and then adding sodium hydroxide solution to adjust the pH to 8.5, and then filtering and removing impurities with a microporous filtration membrane to obtain a composite agent for a boiler;

[0079] The weak acid-weak base copolymer was purchased from outside.

[0080] Embodiment 2

[0081] The present embodiment provides a composite agent for boilers, which comprises, by weight: 25 parts of microcapsules containing weak acid-weak base copolymers, 18 parts of polymaleic acid, 15 parts of polyether-modified silane, 12 parts of nano-graphene oxide, 10 parts of sodium sulfite, 7 parts of polyvinyl pyrrolidone, 6 parts of silicon dioxide, 4 parts of sodium bicarbonate solution, and 55 parts of deionized water. The preparation method of the composite agent for boilers comprises:

[0082] S100, dividing the matrix into two parts, the mass of the first part of the matrix is ​​two-thirds of the total mass of the matrix, and the mass of the second part of the matrix is ​​one-third of the total mass of the matrix, adding nano-graphene oxide to the first part of the matrix and dispersing at a speed of 2100 rpm for 35 minutes to obtain a nano-corrosion inhibitor solution;

[0083] S200, adding sodium sulfite and silicon dioxide to the second matrix and dispersing at a speed of 650 rpm for 30 min to obtain a solution of deoxidizer and anti-settling agent;

[0084] S300, adding microcapsules containing weak acid-weak base copolymer and polymaleic acid to the nano corrosion inhibitor solution, performing a first stirring treatment at 50° C. for 55 minutes, and adding polyether-modified silane during the first stirring treatment to obtain a mixed solution;

[0085] S400, adding the solution of the deoxidizer and the anti-settling agent dropwise to the mixed solution and performing a second stirring treatment at 50° C. for 65 minutes, adding polyvinyl pyrrolidone during the second stirring treatment, and then adding a sodium bicarbonate solution to adjust the pH to 9.5, and then filtering and removing impurities with a microporous filtration membrane to obtain a composite agent for a boiler;

[0086] The preparation method of the microcapsule emulsion containing the weak acid-weak base copolymer comprises:

[0087] S310, adding a weak acid-weak base copolymer to ethanol at a mass ratio of the weak acid-weak base copolymer to ethanol of 0.1:1, and performing ultrasonic dispersion treatment to obtain a weak acid-weak base copolymer solution;

[0088] S320, adding gelatin and Tween 80 to deionized water and dispersing them evenly, wherein the mass ratio of gelatin to deionized water is 0.01:1, and the mass ratio of Tween 80 to weak acid-weak base copolymer is 0.05:1, to obtain a coating material solution;

[0089] S330, dripping the weak acid-weak base copolymer solution into the coating material solution, performing a third stirring treatment at a rotation speed of 2000 rpm for 30 minutes, to obtain microcapsules containing the weak acid-weak base copolymer;

[0090] The weak acid-weak base copolymer is a polyacrylic acid-polymethyl methacrylate copolymer, and the polyacrylic acid-polymethyl methacrylate copolymer is purchased from outside.

[0091] Embodiment 3

[0092] The present embodiment provides a composite agent for boilers, which comprises, by weight: 22 parts of microcapsules containing weak acid-weak base copolymers, 17 parts of polyaspartic acid, 15 parts of polyether-modified silane, 10 parts of nano-ammonium molybdate, 9 parts of sodium isoascorbate, 6 parts of EDTA, 5 parts of carbon nanotubes, 4 parts of sodium bicarbonate solution, and 50 parts of deionized water; wherein the preparation method of the composite agent for boilers comprises:

[0093] S100, dividing the matrix into two parts, the mass of the first part of the matrix is ​​two-thirds of the total mass of the matrix, and the mass of the second part of the matrix is ​​one-third of the total mass of the matrix, adding nano-ammonium molybdate to the first part of the matrix and dispersing it at a speed of 2000 rpm for 35 minutes to obtain a nano-corrosion inhibitor solution;

[0094] S200, adding sodium isoascorbate and carbon nanotubes to the second matrix and dispersing at a rotation speed of 500 rpm for 30 minutes to obtain a solution of deoxidizer and anti-settling agent;

[0095] S300, adding microcapsules containing weak acid-weak base copolymer and polyaspartic acid to the nano corrosion inhibitor solution, performing a first stirring treatment at 50° C. for 55 minutes, and adding polyether-modified silane during the first stirring treatment to obtain a mixed solution;

[0096] S400, adding the solution of deoxidizer and anti-settling agent dropwise to the mixed solution and performing a second stirring treatment at 50° C. for 65 minutes, adding EDTA during the second stirring treatment, and then adding sodium bicarbonate solution to adjust the pH to 9.0, and then filtering and removing impurities with a microporous filtration membrane to obtain a composite agent for boilers;

[0097] The preparation method of the microcapsule emulsion containing the weak acid-weak base copolymer comprises:

[0098] S310, adding a weak acid-weak base copolymer to ethyl acetate at a mass ratio of the weak acid-weak base copolymer to ethyl acetate of 0.3:1, and performing ultrasonic dispersion treatment to obtain a weak acid-weak base copolymer solution;

[0099] S320, adding polyvinyl alcohol and SPAN60 to deionized water and dispersing them evenly, wherein the mass ratio of gelatin to deionized water is 0.1:1, and the mass ratio of SPAN60 to weak acid-weak base copolymer is 0.2:1, to obtain a coating material solution;

[0100] S330, dropping the weak acid-weak base copolymer solution into the coating material solution, performing a third stirring treatment at a rotation speed of 4000 rpm for 10 min, to obtain microcapsules containing the weak acid-weak base copolymer;

[0101] The weak acid-weak base copolymer is a polyacrylic acid-polymethyl methacrylate copolymer, and the preparation method of the polyacrylic acid-polymethyl methacrylate copolymer comprises:

[0102] S311, adding acrylic acid and methacrylic acid to an ethanol aqueous solution, with the mass ratio of acrylic acid, methacrylic acid to the ethanol aqueous solution being 1:1:1.2, and stirring evenly to obtain an acrylic acid-methacrylic acid solution;

[0103] S312, dropping the ammonium persulfate solution into the acrylic acid-methacrylic acid solution, performing a fourth stirring treatment at 60° C. and 300 rpm, adding N,N'-methylenebisacrylamide during the fourth stirring treatment, and then adding vitamin C, and filtering the solution to obtain a polyacrylic acid-polymethyl methacrylate copolymer.

[0104] Embodiment 4

[0105] The present embodiment provides a composite agent for boilers, which comprises, by weight: 22 parts of microcapsules containing weak acid-weak base copolymers, 17 parts of polyaspartic acid, 15 parts of polyether-modified silane, 10 parts of nano-alumina, 9 parts of sodium isoascorbate, 6 parts of EDTA, 5 parts of carbon nanotubes, 4 parts of sodium bicarbonate solution, and 50 parts of deionized water. The preparation method of the composite agent for boilers comprises:

[0106] S100, dividing the matrix into two parts, the mass of the first part of the matrix is ​​two-thirds of the total mass of the matrix, and the mass of the second part of the matrix is ​​one-third of the total mass of the matrix, adding nano-alumina to the first part of the matrix and dispersing at a speed of 2000 rpm for 35 minutes to obtain a nano-corrosion inhibitor solution;

[0107] S200, adding sodium isoascorbate and carbon nanotubes to the second matrix and dispersing at a rotation speed of 500 rpm for 30 minutes to obtain a solution of deoxidizer and anti-settling agent;

[0108] S300, adding microcapsules containing weak acid-weak base copolymer and polyaspartic acid to the nano corrosion inhibitor solution, performing a first stirring treatment at 50° C. for 55 minutes, and adding polyether-modified silane during the first stirring treatment to obtain a mixed solution;

[0109] S400, adding the solution of deoxidizer and anti-settling agent dropwise to the mixed solution and performing a second stirring treatment at 50° C. for 65 minutes, adding EDTA during the second stirring treatment, and then adding sodium bicarbonate solution to adjust the pH to 9.0, and then filtering and removing impurities with a microporous filtration membrane to obtain a composite agent for boilers;

[0110] The preparation method of the microcapsule emulsion containing the weak acid-weak base copolymer comprises:

[0111] S310, adding a weak acid-weak base copolymer to ethyl acetate at a mass ratio of the weak acid-weak base copolymer to ethyl acetate of 0.3:1, and performing ultrasonic dispersion treatment to obtain a weak acid-weak base copolymer solution;

[0112] S320, adding polyvinyl alcohol and SPAN60 to deionized water and dispersing them evenly, wherein the mass ratio of gelatin to deionized water is 0.1:1, and the mass ratio of SPAN60 to weak acid-weak base copolymer is 0.2:1, to obtain a coating material solution;

[0113] S330, dropping the weak acid-weak base copolymer solution into the coating material solution, performing a third stirring treatment at a rotation speed of 4000 rpm for 10 min, to obtain microcapsules containing the weak acid-weak base copolymer;

[0114] The weak acid-weak base copolymer is a polyacrylic acid-polymethyl methacrylate copolymer, and the preparation method of the polyacrylic acid-polymethyl methacrylate copolymer comprises:

[0115] S311, adding acrylic acid and methacrylic acid to an ethanol aqueous solution, with the mass ratio of acrylic acid, methacrylic acid to the ethanol aqueous solution being 1:1:1.2, and stirring evenly to obtain an acrylic acid-methacrylic acid solution;

[0116] S312, dropping the ammonium persulfate solution into the acrylic acid-methacrylic acid solution, performing a fourth stirring treatment at 70° C. and 500 rpm, adding N,N'-methylenebisacrylamide during the fourth stirring treatment, and then adding BHT, and then filtering to obtain a polyacrylic acid-polymethyl methacrylate copolymer.

[0117] Comparative Example

[0118] This comparative example provides a boiler agent, which is purchased from outside and has an organic phosphorus salt as a main component.

[0119] Performance Testing

[0120] Corrosion inhibition performance test: a Q245 carbon steel coupon was placed in a solution simulating boiler water at 90°C for 7 days, and Examples 1-4 and the comparative example were added to the solution to observe the corrosion rate of the carbon steel coupon;

[0121] Scale inhibition performance test: a Q245 carbon steel coupon was placed in a solution simulating boiler water at 150°C, and Examples 1-4 and the comparative example were added to the solution. The solution was circulated at a rate of 1.5 m / s for 3 days, and the scale amount of the carbon steel coupon was detected;

[0122] Dissolved oxygen test: In a solution with an initial dissolved oxygen concentration of 8.0 ppm, Examples 1-4 and the comparative example were added to the solution, and the dissolved oxygen concentration of the solution was tested after 30 minutes.

[0123] The test results are shown in Table 1:

[0124] Table 1

[0125]

[0126] It can be seen from Table 1 that the various properties of Examples 1-4 are better than those of the comparative example, indicating that the composite boiler agent of the present invention has good corrosion resistance and anti-scaling performance, especially the composite boiler agent of Examples 3-4. This may be due to the use of more suitable process parameters and the preparation method of the polyacrylic acid-polymethyl methacrylate copolymer described in the present invention, so that the prepared composite boiler agent has better performance.

[0127] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0128] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A composite agent for boiler, characterized in that: Calculated by mass, including: pH adjuster: 20-25 parts, Dispersant: 15-18 parts, Protective film precursor: 12-15 parts, Nano corrosion inhibitor: 10-12 parts, Deoxidizer: 8-10 parts; Stabilizer: 5-7 parts; Anti-settling agent: 3-6 parts; pH buffer: 2-4 parts; Matrix: 40-55 parts; The preparation method of the composite agent for boiler includes: S100, adding the nano corrosion inhibitor into part of the matrix and dispersing the nano corrosion inhibitor uniformly to obtain a nano corrosion inhibitor solution; S200, adding the deoxidizer and the anti-settling agent to the remaining matrix and dispersing them evenly to obtain a solution of the deoxidizer and the anti-settling agent; S300, adding the pH regulator and the dispersant to the nano corrosion inhibitor solution, performing a first stirring treatment, and adding the protective film precursor during the first stirring treatment to obtain a mixed solution; S400, dropping the solution of the deoxidizer and the anti-settling agent into the mixed solution for a second stirring treatment, adding the stabilizer during the second stirring treatment, and then adding the pH buffer to adjust the pH, to obtain the composite agent for the boiler; The pH adjuster includes microcapsules containing a weak acid-weak base copolymer.

2. The composite agent for boiler according to claim 1, characterized in that: The weak acid-weak base copolymer includes polyacrylic acid-polymethyl methacrylate copolymer.

3. The composite agent for boiler according to claim 2, characterized in that: The dispersant comprises at least one of polymaleic acid, polyacrylic acid and polyaspartic acid; and / or The protective film precursor includes one of polyether-modified silane or sodium molybdate; and / or The nano corrosion inhibitor comprises at least one of nano graphene oxide, nano silicon dioxide, nano ammonium molybdate and nano aluminum oxide.

4. A method for preparing a composite agent for a boiler, characterized in that: Used to prepare the composite agent for boilers as claimed in any one of claims 1 to 3, the preparation method comprising: S100, adding the nano corrosion inhibitor into part of the matrix and dispersing the nano corrosion inhibitor uniformly to obtain a nano corrosion inhibitor solution; S200, adding the deoxidizer and the anti-settling agent to the remaining matrix and dispersing them evenly to obtain a solution of the deoxidizer and the anti-settling agent; S300, adding the pH regulator and the dispersant to the nano corrosion inhibitor solution, performing a first stirring treatment, and adding the protective film precursor during the first stirring treatment to obtain a mixed solution; S400, dropping the solution of the deoxidizer and the anti-settling agent into the mixed solution for a second stirring treatment, adding the stabilizer during the second stirring treatment, and then adding the pH buffer to adjust the pH, to obtain the composite agent for the boiler; The pH adjuster includes a microcapsule emulsion containing a weak acid-weak base copolymer.

5. The preparation method according to claim 4, characterized in that: The preparation method of the microcapsule emulsion containing the weak acid-weak base copolymer comprises: S310, adding the weak acid-weak base copolymer to an organic solvent, and performing ultrasonic dispersion treatment to obtain a weak acid-weak base copolymer solution; S320, adding the coating material and the emulsifier into deionized water and dispersing them evenly to obtain a coating material solution; S330, dropping the weak acid-weak base copolymer solution into the coating material solution, performing a third stirring treatment, and obtaining the microcapsules containing the weak acid-weak base copolymer; Wherein, the weak acid-weak base copolymer comprises a copolymer of polyacrylic acid-polymethyl methacrylate; The coating material includes any one of polyvinyl alcohol, gelatin and porous cyclodextrin.

6. The preparation method according to claim 5, characterized in that: In the S310, the mass ratio of the weak acid-weak base copolymer to the organic solvent is (0.1-0.3):1; and / or In the S320, the mass ratio of the coating material to the deionized water is (0.01-0.1):1; and / or In the S320, the mass ratio of the emulsifier to the weak acid-weak base copolymer is (0.05-0.2):

1.

7. The preparation method according to claim 5, characterized in that: The preparation method of the polyacrylic acid-polymethyl methacrylate copolymer comprises: S311, adding acrylic acid and methacrylic acid into an ethanol aqueous solution, stirring evenly, to obtain an acrylic acid-methacrylic acid solution; S312, dripping the initiator solution into the acrylic acid-methacrylic acid solution, performing a fourth stirring treatment, and adding a crosslinking agent during the fourth stirring treatment to obtain the polyacrylic acid-polymethyl methacrylate copolymer.

8. The preparation method according to claim 7, characterized in that: In the S311, the mass ratio of the acrylic acid, the methacrylic acid and the ethanol aqueous solution is 1:(1-1.5):1.2; and / or In S312, the temperature of the fourth stirring treatment is 60-70° C.; and / or In S312, the rotation speed of the fourth stirring process is 300-500 rpm.

9. The preparation method according to claim 4, characterized in that: In the S300, the temperature of the first stirring treatment is 40-50° C.; and / or In S300, the first stirring treatment lasts for 55-70 minutes; and / or In said S400, the temperature of said second stirring treatment is 45-50°C; and / or In S400, the second stirring treatment lasts for 65-70 minutes.

10. An application of a composite agent for boilers, characterized in that: The boiler composite agent is used for boiler water treatment.

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