Low-phosphorus high-efficiency scale-inhibiting water treatment agent for high-pressure boiler and preparation method thereof

Abstract

The application belongs to the technical field of water treatment agent preparation, and provides a low-phosphorus efficient scale inhibition water treatment agent for high-pressure boilers and a preparation method thereof; firstly, taking cyanuric acid as a core, a carboxyl side chain containing a tert-butoxy carbonyl protection group is introduced, then reacted with methyl methacrylate containing a sulfonic acid group, and finally, the protection group is removed under acidic conditions to obtain sodium isocyanurate bicarboxyl-sulfonic acid; secondly, taking natural dextran as a skeleton, acryloyloxy functional groups are introduced through an active ester method, then allyl segments are connected through an epoxy ring-opening reaction, and finally, mercaptopropionic acid sodium is introduced to obtain double-grafted dextran; thirdly, a variety of vinyl monomers are subjected to aqueous solution copolymerization, and a small amount of a crosslinking agent is introduced, then the polymer is modified by quaternization to obtain a quaternized terpolymer; finally, the above three components are compounded with an auxiliary to obtain an environmentally friendly water treatment composition which has high efficient inhibition capacity on scale and is suitable for severe high-pressure boiler operating environments.

Description

Technical Field

[0001] This invention belongs to the field of water treatment agent preparation technology, and relates to a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. Background Technology

[0002] In the operation of high-pressure boilers, the internal environment is constantly subjected to extreme conditions of high temperature and high pressure, which places extremely high demands on the impurity content of the boiler feedwater. Hardness ions such as calcium and magnesium, as well as silicate compounds, which are commonly found in natural water, easily reach supersaturation on the heating surfaces after continuous evaporation and concentration inside the boiler, leading to crystallization and precipitation, forming hard and dense scale. The thermal conductivity of scale is far lower than that of boiler steel, and its adhesion to the heat exchanger tube walls severely hinders effective heat transfer, significantly reducing boiler thermal efficiency and causing enormous energy waste. Furthermore, the metal tube walls covered by scale cannot be effectively cooled by the boiler water, causing a rapid temperature rise, resulting in decreased mechanical strength and making the metal prone to creep, bulging, and even tube rupture, posing a significant safety hazard.

[0003] To address the aforementioned issues, the selection of water pollution control agents directly impacts both the stable operation of the boiler system and environmental protection. Traditional treatment methods often rely on inorganic phosphates, generating soft sludge that, when combined with blowdown, achieves scale inhibition. However, this method easily produces large amounts of boiler sediment, and phosphorus emissions pose a threat of eutrophication to environmental water bodies. Boiler blowdown, as part of industrial wastewater, contains high concentrations of pollutants such as phosphates, making the treatment process itself a potential pollution source. Therefore, a low-phosphorus water pollution control agent is needed. While subsequent developments of organic polymer scale inhibitors have improved performance, many single or simply compounded polymers have limited thermal stability under high temperature and pressure, and their ability to inhibit and disperse complex mixed scale is insufficient, failing to meet the increasingly demanding requirements of boiler operation. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. First, using cyanuric acid as the core, a novel isocyanuric acid derivative containing multiple carboxyl and sulfonic acid groups is synthesized through a multi-step reaction. Second, using dextran as the backbone, a bifunctional side-chain modified dextran dispersant is prepared. Third, an amphoteric terpolymer is prepared through copolymerization and quaternization modification. Finally, the above three key components are compounded with conventional additives to obtain a synergistic final product, thereby meeting the needs of actual production.

[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 low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers, the preparation method comprising:

[0007] S1, cyanuric acid, dimethyl sulfoxide and p-methoxyphenol are mixed and nitrogen gas is introduced, and triethylamine and tert-butyl acrylate are added to react to obtain N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. Sodium 2-ethanesulfonate methacrylate is added to N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid to react, followed by the addition of trifluoroacetic acid. The pH is then adjusted to 8.0-8.5 with sodium bicarbonate solution and stirred to obtain sodium dicarboxy-sulfonate isocyanurate.

[0008] S2, dextran, anhydrous dimethyl sulfoxide and triethylamine are mixed and nitrogen gas is introduced, 4-dimethylaminopyridine, p-methoxyphenol and N-acryloyloxysuccinimide are added and reacted to obtain N-acryloyloxysuccinimide esterified dextran, then allyl glycidyl ether is added to N-acryloyloxysuccinimide esterified dextran and reacted with anhydrous sodium carbonate, then sodium 3-mercaptopropionate is added and reacted with azobisisobutyronitrile to obtain double-grafted dextran;

[0009] S3, Acrylamide, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid, N,N′-methylenebisacrylamide and ammonium persulfate are dispersed in deionized water and reacted to obtain an aqueous copolymer solution. The aqueous copolymer solution is then cooled and reacted with formaldehyde solution and dimethylamine aqueous solution. The pH is adjusted to 11.5-11.8 and (3-chloro-2-hydroxypropyl)trimethylammonium chloride aqueous solution is added to react to obtain a quaternized terpolymer.

[0010] S4, sodium dicarboxy-sulfonate isocyanurate, double-grafted dextran, quaternized terpolymer, 1,2-benzisothiazolin-3-one, polydimethylsiloxane emulsion, toluenetriazole and deionized water are mixed to obtain a low-phosphorus and high-efficiency scale inhibitor water treatment agent for high-pressure boilers.

[0011] Specifically, it includes:

[0012] S1, cyanuric acid, dimethyl sulfoxide and p-methoxyphenol are mixed and nitrogen gas is introduced. The temperature is adjusted to the first temperature and triethylamine and tert-butyl acrylate are added to react and N,N'-diisocyanuric acid is obtained. The mixture is cooled to room temperature and sodium 2-ethanesulfonate methacrylate is added to N,N'-diisocyanuric acid. The temperature is adjusted to the first temperature and the reaction continues. After the reaction is completed, the temperature is adjusted to the second temperature, trifluoroacetic acid is added and the temperature is adjusted to room temperature. The pH is then adjusted to 8.0-8.5 with sodium bicarbonate solution and stirred. After concentration under reduced pressure, the mixture is poured into anhydrous ethanol to precipitate, filtered, washed and dried to obtain sodium dicarboxy-sulfonate isocyanurate.

[0013] S2, dextran, anhydrous dimethyl sulfoxide, and triethylamine were mixed and nitrogen gas was introduced. After adjusting the temperature to the third temperature, 4-dimethylaminopyridine, p-methoxyphenol, and N-acryloyloxysuccinimide were added. The temperature was adjusted to the fourth temperature to obtain N-acryloyloxysuccinimide esterified dextran. Allyl glycidyl ether and anhydrous sodium carbonate were then added to the N-acryloyloxysuccinimide esterified dextran. The pH was adjusted to 10.5-11.0, and the temperature was adjusted to the fourth temperature to continue the reaction. Then, sodium 3-mercaptopropionate and azobisisobutyronitrile were added, and the temperature was adjusted to the fifth temperature to react under nitrogen gas. After the reaction was completed, the reaction solution was poured into anhydrous ethanol to precipitate, and then placed in a dialysis bag and dialyzed in deionized water. After freeze-drying, double-grafted dextran was obtained.

[0014] S3, acrylamide, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid, N,N′-methylenebisacrylamide and ammonium persulfate are dispersed in deionized water and the pH is adjusted to 6.2–6.8 with sodium hydroxide solution. Under a nitrogen atmosphere, the reaction is carried out at temperature five to obtain an aqueous copolymer solution. The aqueous copolymer solution is then cooled to temperature six and the pH is adjusted to 7.8–8.2. Formaldehyde solution and dimethylamine aqueous solution are added and reacted at temperature six. The pH is then adjusted to 11.5–11.8 and the temperature is adjusted to temperature five. Trimethylammonium chloride aqueous solution is added and the reaction continues. After cooling, the pH is adjusted to 7.0–7.5 to obtain a quaternized terpolymer.

[0015] S4, sodium dicarboxy-sulfonate isocyanurate, double-grafted dextran, quaternized terpolymer, 1,2-benzisothiazolin-3-one, polydimethylsiloxane emulsion, toluenetriazole and deionized water are mixed to obtain a low-phosphorus and high-efficiency scale inhibitor water treatment agent for high-pressure boilers.

[0016] In S1, cyanuric acid is used as the central core. Two flexible alkyl chains are introduced onto its nitrogen atom via a Michael addition reaction. Each chain terminates with a carboxyl functional group. These two carboxyl groups, through the lone pair electrons on their oxygen atoms, can coordinate with divalent metal cations such as calcium and magnesium in the water via chelation or bridging, effectively reducing the activity of free scale-forming cations in the solution. This thermodynamically increases the solubility product threshold of the scale-forming ion product, thereby inhibiting crystal nucleus formation. Subsequently, using the remaining NH active sites, sodium 2-ethanesulfonate methacrylate is introduced to obtain a molecule containing a strongly acidic sulfonic acid group. The sulfonic acid group ionizes in water, allowing it to adsorb onto the surface of nascent, positively charged calcium carbonate microcrystals via electrostatic attraction. This adsorption behavior occupies the active growth sites of the crystals, disrupting the regular arrangement of the crystal lattice. This prevents subsequent ions from stacking according to the normal crystal lattice, constituting a dual inhibition mechanism against scale formation.

[0017] In S2, a natural polysaccharide is used as the main chain. First, an acryloyloxy side chain is introduced through grafting of N-acryloyloxysuccinimide. The carboxyl group on the side chain also has the ability to coordinate with scale-forming cations, which can further enhance the interference with crystal growth. Second, an allyl side chain is introduced through allyl glycidyl ether, and then sodium 3-mercaptopropionate is linked to it, introducing a carboxyl functional group again. A freely rotating sodium propionate side chain is connected through a flexible thioether bond, forming a steric hindrance effect. When this macromolecule is adsorbed onto the surface of scale particles, the aggregation between particles is prevented through steric repulsion. Multiple different types of side chains (acryloyloxy and sodium thiopropionate groups) provide abundant adsorption sites, which can encapsulate scale particles and corrosion products such as iron oxide particles in the water. The high water solubility of the main chain allows these encapsulated particles to be stably suspended in the water and discharged with boiler blowdown.

[0018] In S3, the copolymer backbone consists of three monomers: acrylamide, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid. The maleic anhydride unit hydrolyzes in water to form an ortho-dicarboxylic acid structure, providing strong calcium ion chelating sites. The 2-acrylamido-2-methylpropanesulfonic acid unit introduces a strongly acidic sulfonic acid group, which not only enhances the polymer's electronegativity for adsorption onto the scale surface, but its unique structure also endows the polymer with excellent resistance to calcium ion precipitation and hydrolytic stability at high temperatures. N,N'-methylenebisacrylamide acts as a crosslinking agent, forming a mild network structure, which enhances the rigidity of the molecular chain and the steric hindrance effect after adsorption. Subsequently, through reaction with (3-chloro-2-hydroxypropyl)trimethylammonium chloride, quaternary ammonium cationic groups were introduced into the polymer chain. This resulted in the presence of a large number of anionic centers (carboxyl groups, sulfonic acid groups) and cationic centers (quaternary ammonium groups) on the polymer molecular chain, forming an amphoteric structure. This structure can more effectively adsorb and disperse particles with different surface charges. On the other hand, the quaternary ammonium cationic group itself is an effective anodic corrosion inhibitor. It can adsorb onto the metal surface of the boiler to form a dense protective film, inhibiting the anodic dissolution process of the metal and thus playing a role in corrosion inhibition.

[0019] As a preferred embodiment of the present invention, in S1, the mass-to-volume ratio of cyanuric acid, dimethyl sulfoxide, p-methoxyphenol, triethylamine, and tert-butyl acrylate is (13-14) g: 200 mL: (0.2-0.25) g: (2.0-2.5) g: (26-27) g, for example, it can be (13.0, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, or 14.0) g: 200 mL: (0.2, 0.205 ... 21, 0.215, 0.22, 0.225, 0.23, 0.235, 0.24, 0.245 or 0.25) g; (2.0, 2.05, 2.1, 2.15, 2.2, 2.25, 2.3, 2.35, 2.4, 2.45 or 2.5) g; (26, 26.1, 26.2, 26.3, 26.4, 26.5, 26.6, 26.7, 26.8, 26.9 or 27) g, but not limited to the listed values, other unlisted values ​​within this range also apply.

[0020] In some alternative embodiments, the first temperature is 45-50°C, for example, it can be 45°C, 45.5°C, 46°C, 46.5°C, 47°C, 47.5°C, 48°C, 48.5°C, 49°C, 49.5°C or 50°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0021] In some optional embodiments, the reaction time of adding triethylamine and tert-butyl acrylate is 8-10 h, for example, 8.0 h, 8.2 h, 8.4 h, 8.6 h, 8.8 h, 9.0 h, 9.2 h, 9.4 h, 9.6 h, 9.8 h or 10.0 h, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0022] In some optional embodiments, the mass-to-volume ratio of cyanuric acid, sodium 2-ethanesulfonate methacrylate, and trifluoroacetic acid is (13-14) g:(23-24) g:(40-60) mL, for example, it can be (13.0, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, or 14.0) g:(23, 23.1, 23.2, 23.3, 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, or 24) g:(40, 42, 44, 46, 48, 50, 52, 54, 56, 58, or 60) mL, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the reaction continues at the first temperature for 2-4 hours, for example, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, or 4.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0024] In some alternative embodiments, the second temperature is 0-5°C, for example, it can be 0°C, 0.5°C, 1°C, 1.5°C, 2°C, 2.5°C, 3°C, 3.5°C, 4°C, 4.5°C or 5°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0025] In some alternative embodiments, the room temperature reaction time is 1-2 hours, for example, 1.0 hours, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours, 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, or 2.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0026] As a preferred embodiment of the present invention, in S2, the mass-to-volume ratio of dextran, anhydrous dimethyl sulfoxide, triethylamine, 4-dimethylaminopyridine, p-methoxyphenol, and N-acryloyloxysuccinimide is (10-11) g: 120 mL: (0.5-0.7) mL: 0.12 g: 0.002 g: (2.5-2.7) g, for example, it can be (10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8) g. 10.9 or 11.0) g: 120 mL: (0.5, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68 or 0.7) mL: 0.12 g: 0.002 g: (2.5, 2.52, 2.54, 2.56, 2.58, 2.6, 2.62, 2.64, 2.66, 2.68 or 2.7) g, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0027] In some alternative embodiments, the third temperature is 28-32°C, for example, it can be 28.0°C, 28.4°C, 28.8°C, 29.2°C, 29.6°C, 30.0°C, 30.4°C, 30.8°C, 31.2°C, 31.6°C or 32.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] In some alternative embodiments, the fourth temperature is 35-40°C, for example, it can be 35°C, 35.5°C, 36°C, 36.5°C, 37°C, 37.5°C, 38°C, 38.5°C, 39°C, 39.5°C or 40°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the reaction time at the fourth temperature is 12-18 hours, for example, 12.0 hours, 12.6 hours, 13.2 hours, 13.8 hours, 14.4 hours, 15.0 hours, 15.6 hours, 16.2 hours, 16.8 hours, 17.4 hours, or 18.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the mass ratio of dextran, allyl glycidyl ether, and anhydrous sodium carbonate is (10-11):(3-3.5):(0.5-0.6), for example, it can be (10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, or 11.0):(3.0, 3.05, 3.1, 3.15, 3.2, 3.25, 3.3, 3.35, 3.4, 3.45, or 3.5):(0.5, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, or 0.6), but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the mass ratio of dextran, sodium 3-mercaptopropionate, and azobisisobutyronitrile is (10-11):(3-3.2):0.05, for example, it can be (10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, or 11.0):(3.0, 3.02, 3.04, 3.06, 3.08, 3.1, 3.12, 3.14, 3.16, 3.18, or 3.2):0.05, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the reaction continues at the fourth temperature for 6-8 hours, for example, 6.0 hours, 6.2 hours, 6.4 hours, 6.6 hours, 6.8 hours, 7.0 hours, 7.2 hours, 7.4 hours, 7.6 hours, 7.8 hours, or 8.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0033] In some optional embodiments, the reaction time under nitrogen is 3-5 hours, for example, 3.0 hours, 3.2 hours, 3.4 hours, 3.6 hours, 3.8 hours, 4.0 hours, 4.2 hours, 4.4 hours, 4.6 hours, 4.8 hours, or 5.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0034] In some optional embodiments, the dialysis bag has a molecular weight cutoff of 3500 Da.

[0035] In some optional embodiments, the dialysis time is 48-72 hours, for example, 48.0 hours, 50.4 hours, 52.8 hours, 55.2 hours, 57.6 hours, 60.0 hours, 62.4 hours, 64.8 hours, 67.2 hours, 69.6 hours, or 72.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0036] As a preferred embodiment of the present invention, in S3, the mass ratio of acrylamide, maleic anhydride, 2-acrylamido-2-methylpropanesulfonic acid, N,N′-methylenebisacrylamide, ammonium persulfate, and deionized water is (180-185):(23-24):(100-105):0.5:(5-6):800, for example, it can be (180, 180.5, 181, 181.5, 182, 182.5, 183, 183.5, 184, 184.5 or 185):(23, 23). 1, 23.2, 23.3, 23.4, 23.5, 23.6, 23.7, 23.8, 23.9 or 24: (100, 100.5, 101, 101.5, 102, 102.5, 103, 103.5, 104, 104.5 or 105): 0.5: (5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9 or 6.0): 800, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0037] In some optional embodiments, the fifth temperature is 70-78°C, for example, it can be 70°C, 70.8°C, 71.6°C, 72.4°C, 73.2°C, 74.0°C, 74.8°C, 75.6°C, 76.4°C, 77.2°C or 78°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the reaction time at the fifth temperature is 4-5 hours, for example, 4.0 hours, 4.1 hours, 4.2 hours, 4.3 hours, 4.4 hours, 4.5 hours, 4.6 hours, 4.7 hours, 4.8 hours, 4.9 hours, or 5.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0039] In some alternative embodiments, the sixth temperature is 38-42°C, for example, it can be 38.0°C, 38.4°C, 38.8°C, 39.2°C, 39.6°C, 40.0°C, 40.4°C, 40.8°C, 41.2°C, 41.6°C or 42.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] In some optional embodiments, the mass ratio of the acrylamide, formaldehyde solution, dimethylamine aqueous solution, and (3-chloro-2-hydroxypropyl)trimethylammonium chloride aqueous solution is (180-185):(12-13):(17-17.5):(27-28), for example, it can be (180, 180.5, 181, 181.5, 182, 182.5, 183, 183.5, 184, 184.5, or 185):(12.0, 12.1, 12.2, 12.3, 12.4). 12.5, 12.6, 12.7, 12.8, 12.9 or 13.0: (17, 17.05, 17.1, 17.15, 17.2, 17.25, 17.3, 17.35, 17.4, 17.45 or 17.5): (27, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9 or 28), but not limited to the listed values, other unlisted values ​​within this range also apply.

[0041] In some optional embodiments, the formaldehyde solution has a mass fraction of 37 wt.%.

[0042] In some optional embodiments, the dimethylamine aqueous solution has a mass fraction of 40 wt.%.

[0043] In some optional embodiments, the aqueous solution of (3-chloro-2-hydroxypropyl)trimethylammonium chloride has a mass fraction of 65 wt.%.

[0044] In some optional embodiments, the reaction time at the sixth temperature is 1.5-2.5 h, for example, it can be 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2.0 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h or 2.5 h, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the continued reaction time is 3-4 hours, for example, 3.0 hours, 3.1 hours, 3.2 hours, 3.3 hours, 3.4 hours, 3.5 hours, 3.6 hours, 3.7 hours, 3.8 hours, 3.9 hours, or 4.0 hours, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0046] As a preferred embodiment of the present invention, in S4, the mass ratio of sodium dicarboxy-sulfonate isocyanurate, double-grafted dextran, quaternized terpolymer, 1,2-benzisothiazolin-3-one, polydimethylsiloxane emulsion, toluenetriazole, and deionized water is (87-90):(50-55):(375-395):2:1:1:500, for example, it can be (87, 87.3, 87.6, 87.9, 88.2, 88.5). 88.8, 89.1, 89.4, 89.7 or 90: (50, 50.5, 51, 51.5, 52, 52.5, 53, 53.5, 54, 54.5 or 55): (375, 377, 379, 381, 383, 385, 387, 389, 391, 393 or 395): 2:1:1:500, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0047] In a second aspect, the present invention provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers, prepared by the preparation method described in the first aspect.

[0048] Compared with existing technologies, the beneficial effects of this invention are as follows: First, by preparing sodium dicarboxy-sulfonic acid isocyanurate, this invention can simultaneously exert complexation and solubilization effects and lattice distortion effects under high temperature and high pressure, exhibiting a stronger threshold inhibition effect on scale-forming ions and effectively preventing the initial nucleation of scale from the source. Second, the double-grafted modified dextran uses renewable natural polymers as its backbone and introduces various functional groups through multi-step chemical modification. It is not only green and environmentally friendly and easily biodegradable, but its unique spatial structure also endows it with super dispersing ability, effectively encapsulating the distorted microcrystals and preventing their aggregation and deposition. Third, the zwitterionic terpolymer prepared by this invention has anionic and cationic groups and sulfonic acid groups with strong hydration ability on its molecular chain, giving it dispersibility and corrosion inhibition properties for calcium and magnesium ions and corrosion products such as iron oxide in boiler water. Finally, this invention prepares a low-phosphorus, high-efficiency scale inhibitor for water pollution prevention and control, which to a certain extent avoids eutrophication of water bodies and has excellent environmental friendliness. Detailed Implementation

[0049] 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 those that make any obvious substitutions and modifications to the embodiments described herein.

[0050] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0051] Example 1

[0052] This embodiment provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The preparation method specifically includes the following steps:

[0053] S1, 13g of cyanuric acid, 200mL of dimethyl sulfoxide and 0.25g of p-methoxyphenol were mixed and nitrogen gas was introduced. The temperature was adjusted to 50℃ and 2.0g of triethylamine and 27g of tert-butyl acrylate were added and reacted for 8h to obtain N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The mixture was cooled to room temperature and 23g of sodium 2-ethanesulfonate methacrylate was added to the N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The temperature was adjusted to 45℃ and the reaction was continued for 4h. After the reaction was completed, the temperature was adjusted to 0℃, 60mL of trifluoroacetic acid was added and the temperature was adjusted to room temperature and the reaction was continued for 1h. The pH was then adjusted to 8.0 with sodium bicarbonate solution and stirred. After concentration under reduced pressure, the mixture was poured into anhydrous ethanol for precipitation, filtered, washed and dried to obtain sodium dicarboxy-sulfonate isocyanurate.

[0054] S2, 10g dextran, 120mL anhydrous dimethyl sulfoxide, and 0.7mL triethylamine were mixed and nitrogen gas was introduced. After adjusting the temperature to 32℃, 0.12g 4-dimethylaminopyridine, 0.002g p-methoxyphenol, and 2.5g N-acryloyloxysuccinimide were added. The temperature was adjusted to 40℃ and the reaction was carried out for 12h to obtain N-acryloyloxysuccinimide esterified dextran. Then, 3.5g allyl glycidyl ether and 0.5g anhydrous sodium carbonate were added to the N-acryloyloxysuccinimide esterified dextran. The pH was adjusted to 10.5, and the temperature was adjusted to 35℃ and the reaction was continued for 8h. Finally, 3.2g of... Sodium 3-mercaptopropionate was reacted with 0.05 g of azobisisobutyronitrile at 70 °C under nitrogen for 3 h. After the reaction was completed, the reaction solution was poured into anhydrous ethanol to precipitate the precipitate. The precipitate was then placed in a dialysis bag with a molecular weight cutoff of 3500 Da and dialyzed in deionized water for 72 h. The precipitate was then freeze-dried to obtain double-grafted dextran.

[0055] S3, 185g acrylamide, 23g maleic anhydride, 105g 2-acrylamido-2-methylpropanesulfonic acid, 0.50g N,N′-methylenebisacrylamide and 5g ammonium persulfate were dispersed in 800g deionized water and the pH was adjusted to 6.2 with sodium hydroxide solution. The reaction was carried out under a nitrogen atmosphere at 78℃ for 4.0h to obtain a copolymer aqueous solution. The copolymer aqueous solution was then cooled to 38℃ and the pH was adjusted to 8.2. 13g of 37wt.% formaldehyde solution and 17g of 40wt.% dimethylamine aqueous solution were added and reacted at 42℃ for 1.5h. The pH was then adjusted to 11.5 and the temperature was adjusted to 70℃. 27g of 65wt.% (3-chloro-2-hydroxypropyl)trimethylammonium chloride aqueous solution was added and the reaction was continued for 4h. After cooling, the pH was adjusted to 7.0 to obtain a quaternized terpolymer.

[0056] S4. 87g of sodium dicarboxy-sulfonate isocyanurate, 55g of double-grafted dextran, 375g of quaternized terpolymer, 2g of 1,2-benzisothiazolin-3-one, 1g of polydimethylsiloxane emulsion, 1g of toluenetriazole and 500g of deionized water are mixed to obtain a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers.

[0057] Example 2

[0058] This embodiment provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The preparation method specifically includes the following steps:

[0059] S1, 14g of cyanuric acid, 200mL of dimethyl sulfoxide and 0.20g of p-methoxyphenol were mixed and nitrogen gas was introduced. The temperature was adjusted to 45℃ and 2.5g of triethylamine and 26g of tert-butyl acrylate were added and reacted for 10h to obtain N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The mixture was cooled to room temperature and 24g of sodium 2-ethanesulfonate methacrylate was added to the N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The temperature was adjusted to 50℃ and the reaction was continued for 2h. After the reaction was completed, the temperature was adjusted to 5℃, 40mL of trifluoroacetic acid was added and the temperature was adjusted to room temperature and the reaction was continued for 2h. The pH was then adjusted to 8.5 with sodium bicarbonate solution and stirred. After concentration under reduced pressure, the mixture was poured into anhydrous ethanol for precipitation, filtered, washed and dried to obtain sodium dicarboxy-sulfonate isocyanurate.

[0060] S2, 11g of dextran, 120 mL of anhydrous dimethyl sulfoxide, and 0.5 mL of triethylamine were mixed and nitrogen gas was introduced. After adjusting the temperature to 28℃, 0.12g of 4-dimethylaminopyridine, 0.002g of p-methoxyphenol, and 2.7g of N-acryloyloxysuccinimide were added. The temperature was adjusted to 35℃ and the reaction was carried out for 18h to obtain N-acryloyloxysuccinimide esterified dextran. Then, 3.0g of allyl glycidyl ether and 0.6g of anhydrous sodium carbonate were added to the N-acryloyloxysuccinimide esterified dextran. The pH was adjusted to 11.0, and the temperature was adjusted to 40℃ and the reaction was continued for 6h. Then, 3g of... Sodium 3-mercaptopropionate was reacted with 0.05 g of azobisisobutyronitrile at 60 °C under nitrogen for 5 h. After the reaction was completed, the reaction solution was poured into anhydrous ethanol to precipitate the precipitate. The precipitate was then placed in a dialysis bag with a molecular weight cutoff of 3500 Da and dialyzed in deionized water for 48 h. The precipitate was then freeze-dried to obtain double-grafted dextran.

[0061] S3, 180g acrylamide, 24g maleic anhydride, 100g 2-acrylamido-2-methylpropanesulfonic acid, 0.50g N,N′-methylenebisacrylamide and 6g ammonium persulfate were dispersed in 800g deionized water and the pH was adjusted to 6.8 with sodium hydroxide solution. The reaction was carried out under a nitrogen atmosphere at 70℃ for 5.0h to obtain an aqueous copolymer solution. The aqueous copolymer solution was then cooled to 42℃ and the pH was adjusted to 7.8. 12g of formaldehyde solution (37wt.%) and 17.5g of dimethylamine aqueous solution (40wt.%) were added and the reaction was carried out at 38℃ for 2.5h. The pH was then adjusted to 11.8 and the temperature was adjusted to 60℃. 28g of (3-chloro-2-hydroxypropyl)trimethylammonium chloride aqueous solution (65wt.%) was added and the reaction was continued for 3h. After cooling, the pH was adjusted to 7.5 to obtain a quaternized terpolymer.

[0062] S4. 90g of sodium dicarboxy-sulfonate isocyanurate, 50g of double-grafted dextran, 395g of quaternized terpolymer, 2g of 1,2-benzisothiazolin-3-one, 1g of polydimethylsiloxane emulsion, 1g of toluenetriazole and 500g of deionized water are mixed to obtain a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers.

[0063] Example 3

[0064] This embodiment provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The preparation method specifically includes the following steps:

[0065] S1, 13.5g of cyanuric acid, 200mL of dimethyl sulfoxide and 0.22g of p-methoxyphenol were mixed and nitrogen gas was introduced. The temperature was adjusted to 48℃ and 2.2g of triethylamine and 26.5g of tert-butyl acrylate were added and reacted for 9h to obtain N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The mixture was cooled to room temperature and 23.5g of sodium 2-ethanesulfonate methacrylate was added to the N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The temperature was adjusted to 48℃ and the reaction was continued for 3h. After the reaction was completed, the temperature was adjusted to 2℃, 50mL of trifluoroacetic acid was added and the temperature was adjusted to room temperature and the reaction was continued for 1.5h. The pH was then adjusted to 8.2 with sodium bicarbonate solution and stirred. After concentration under reduced pressure, the mixture was poured into anhydrous ethanol for precipitation, filtered, washed and dried to obtain sodium dicarboxy-sulfonate isocyanurate.

[0066] S2, 10.5 g dextran, 120 mL anhydrous dimethyl sulfoxide, and 0.6 mL triethylamine were mixed and nitrogen gas was introduced. After adjusting the temperature to 30 °C, 0.12 g 4-dimethylaminopyridine, 0.002 g p-methoxyphenol, and 2.6 g N-acryloyloxysuccinimide were added. The temperature was adjusted to 38 °C and the reaction was carried out for 15 h to obtain N-acryloyloxysuccinimide esterified dextran. Then, 3.2 g allyl glycidyl ether and 0.55 g anhydrous sodium carbonate were added to the N-acryloyloxysuccinimide esterified dextran. The pH was adjusted to 10.8, and the temperature was adjusted to 38 °C and the reaction was continued for 7 h. Then, 3.1 g of... Sodium 3-mercaptopropionate was reacted with 0.05 g of azobisisobutyronitrile at 65 °C under nitrogen for 4 h. After the reaction was completed, the reaction solution was poured into anhydrous ethanol to precipitate the precipitate. The precipitate was then placed in a dialysis bag with a molecular weight cutoff of 3500 Da and dialyzed in deionized water for 60 h. The precipitate was then freeze-dried to obtain double-grafted dextran.

[0067] S3, 182g acrylamide, 23.5g maleic anhydride, 102g 2-acrylamido-2-methylpropanesulfonic acid, 0.50g N,N′-methylenebisacrylamide and 5.5g ammonium persulfate were dispersed in 800g deionized water and the pH was adjusted to 6.5 with sodium hydroxide solution. The reaction was carried out under a nitrogen atmosphere at 75℃ for 4.5h to obtain an aqueous copolymer solution. The aqueous copolymer solution was then cooled to 40℃ and the pH was adjusted to 8.0. 12.5g of formaldehyde solution (37wt.%) and 17.2g of dimethylamine aqueous solution (40wt.%) were added and reacted at 40℃ for 2.0h. The pH was then adjusted to 11.6 and the temperature was adjusted to 65℃. 27.5g of (3-chloro-2-hydroxypropyl)trimethylammonium chloride aqueous solution (65wt.%) was added and the reaction was continued for 3.5h. After cooling, the pH was adjusted to 7.2 to obtain a quaternized terpolymer.

[0068] S4. 88g of sodium dicarboxy-sulfonate isocyanurate, 52g of double-grafted dextran, 380g of quaternized terpolymer, 2g of 1,2-benzisothiazolin-3-one, 1g of polydimethylsiloxane emulsion, 1g of toluenetriazole and 500g of deionized water are mixed to obtain a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers.

[0069] Example 4

[0070] This embodiment provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The preparation method specifically includes the following steps:

[0071] S1, 13.2 g of cyanuric acid, 200 mL of dimethyl sulfoxide and 0.24 g of p-methoxyphenol were mixed and nitrogen gas was introduced. The temperature was adjusted to 46 °C and 2.4 g of triethylamine and 26.2 g of tert-butyl acrylate were added and reacted for 9.5 h to obtain N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The mixture was cooled to room temperature and 23.8 g of sodium 2-ethanesulfonate methacrylate was added to the N,N'-bis(2-tert-butoxycarbonylethyl)isocyanuric acid. The temperature was adjusted to 46 °C and the reaction was continued for 2.5 h. After the reaction was completed, the temperature was adjusted to 4 °C, 45 mL of trifluoroacetic acid was added and the temperature was adjusted to room temperature and the reaction was continued for 1.8 h. The pH was then adjusted to 8.4 with sodium bicarbonate solution and stirred. After concentration under reduced pressure, the mixture was poured into anhydrous ethanol for precipitation, filtered, washed and dried to obtain sodium dicarboxy-sulfonate isocyanurate.

[0072] S2, 10.8 g dextran, 120 mL anhydrous dimethyl sulfoxide, and 0.55 mL triethylamine were mixed and nitrogen gas was introduced. After adjusting the temperature to 31 °C, 0.12 g 4-dimethylaminopyridine, 0.002 g p-methoxyphenol, and 2.55 g N-acryloyloxysuccinimide were added. The temperature was adjusted to 36 °C and the reaction was carried out for 16 h to obtain N-acryloyloxysuccinimide esterified dextran. Then, 3.4 g allyl glycidyl ether and 0.58 g anhydrous sodium carbonate were added to the N-acryloyloxysuccinimide esterified dextran. The pH was adjusted to 10.6, and the temperature was adjusted to 39 °C and the reaction was continued for 6.5 h. Finally, 3.05 g of... Sodium 3-mercaptopropionate was reacted with 0.05 g of azobisisobutyronitrile at 68 °C under nitrogen for 4.5 h. After the reaction was completed, the reaction solution was poured into anhydrous ethanol to precipitate the precipitate. The precipitate was then placed in a dialysis bag with a molecular weight cutoff of 3500 Da and dialyzed in deionized water for 55 h. The precipitate was then freeze-dried to obtain double-grafted dextran.

[0073] S3, 184g acrylamide, 23.8g maleic anhydride, 104g 2-acrylamido-2-methylpropanesulfonic acid, 0.50g N,N′-methylenebisacrylamide and 5.2g ammonium persulfate were dispersed in 800g deionized water and the pH was adjusted to 6.6 with sodium hydroxide solution. The reaction was carried out under a nitrogen atmosphere at 72℃ for 4.8h to obtain an aqueous copolymer solution. The aqueous copolymer solution was then cooled to 41℃ and the pH was adjusted to 8.1. 12.8g of formaldehyde solution (37wt.%) and 17.4g of dimethylamine aqueous solution (40wt.%) were added and reacted at 41℃ for 2.2h. The pH was then adjusted to 11.7 and the temperature was adjusted to 62℃. 27.2g of (3-chloro-2-hydroxypropyl)trimethylammonium chloride aqueous solution (65wt.%) was added and the reaction was continued for 3.8h. After cooling, the pH was adjusted to 7.4 to obtain a quaternized terpolymer.

[0074] S4. 89g of sodium dicarboxy-sulfonate isocyanurate, 54g of double-grafted dextran, 390g of quaternized terpolymer, 2g of 1,2-benzisothiazolin-3-one, 1g of polydimethylsiloxane emulsion, 1g of toluenetriazole and 500g of deionized water are mixed to obtain a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers.

[0075] Comparative Example 1

[0076] This comparative example provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The difference between this example and Example 1 is that the mass of sodium dicarboxy-sulfonate isocyanurate in S4 is 0, while other process parameters and operating conditions are exactly the same as in Example 1.

[0077] Comparative Example 2

[0078] This comparative example provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The difference between this example and Example 1 is that the mass of double-grafted dextran in S4 is 0, while other process parameters and operating conditions are exactly the same as in Example 1.

[0079] Comparative Example 3

[0080] This comparative example provides a low-phosphorus, high-efficiency scale inhibitor water treatment agent for high-pressure boilers and its preparation method. The difference between this example and Example 1 is that the mass of the quaternized terpolymer in S4 is 0, while the other process parameters and operating conditions are exactly the same as in Example 1.

[0081] The performance of the low-phosphorus, high-efficiency scale inhibitors prepared in Examples 1-4 and Comparative Examples 1-3 was tested using the following methods.

[0082] The test method for scale inhibition performance is GB / T16632-2019;

[0083] The corrosion inhibition performance test method is HG / T2387-2007.

[0084] High-temperature / alkali stability test method: Prepare 20g of low-phosphorus high-efficiency scale inhibitor water treatment agent with 80g of deionized water and adjust the pH to 10.0-10.5 with 10wt.% sodium hydroxide solution. Add sodium carbonate / sodium bicarbonate mixture to make the total alkalinity 5-10mmol / L. After degassing with nitrogen for 5-10min, dispense into pressure-resistant bushings, leaving ≥1 / 3 space to buffer steam pressure. Slowly introduce nitrogen into the reactor for 1-2min to purge air. Aging at 180℃ for 4h, cool to room temperature, and allow to cool naturally to room temperature or in a water bath to ≤30℃. Open the lid and take a sample. If the pH drifts, use 10wt.% NaOH or dilute hydrochloric acid to fine-tune the sample pH back to 9.0-9.3. If there is a small amount of volatilization loss, add water to the original mass and check whether the appearance shows layering, turbidity, or precipitation.

[0085] The test results are shown in Table 1.

[0086] Table 1. Test results of low-phosphorus, high-efficiency scale inhibitor water treatment agents in Examples 1-4 and Comparative Examples 1-3

[0087]

[0088] As shown in Table 1, compared to Example 1, Comparative Example 1 showed a decrease in scale inhibition rate, a decrease in corrosion inhibition rate, and a more cloudy appearance; Comparative Example 2 showed a decrease in scale inhibition rate, a decrease in corrosion inhibition rate, and a more cloudy appearance; and Comparative Example 3 showed a decrease in scale inhibition rate, a decrease in corrosion inhibition rate, a more cloudy appearance, and the appearance of precipitate. This is because the mass of sodium dicarboxylate-sulfonate is 0 in Comparative Example 1, resulting in the loss of the carboxyl complexation effect, an increase in the concentration of calcium ions, and easier formation of primary crystal nuclei, leading to a decrease in scale inhibition rate. In Comparative Example 2, the mass of double-grafted dextran is 0, resulting in the loss of brush-like steric hindrance and multi-point coating, making the particles more prone to collision and aggregation, thus leading to a decrease in scale inhibition rate, a decrease in corrosion inhibition rate, and a more cloudy appearance. In Comparative Example 3, the mass of the quaternized terpolymer is 0, resulting in poor adsorption and dispersion of particles with different surface charges, the absence of a quaternary ammonium adsorption layer on the metal surface, and a decrease in corrosion inhibition ability, thus leading to a decrease in scale inhibition rate, a decrease in corrosion inhibition rate, a more cloudy appearance, and the appearance of precipitate.

[0089] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations 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 scope of protection and disclosure of the present invention.

Claims

1. A process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers, characterized by, The preparation method comprises: S1, mixing cyanuric acid, dimethyl sulfoxide and p-methoxyphenol, and passing nitrogen, and adding triethylamine and t-butyl acrylate to react to obtain N,N'-bis(2-tert-butoxycarbonyl ethyl) isocyanuric acid, adding 2-ethylsulfonate sodium salt of methacrylic acid to N,N'-bis(2-tert-butoxycarbonyl ethyl) isocyanuric acid to react, then adding trifluoroacetic acid, and then using sodium bicarbonate solution to adjust the pH to 8.0-8.5 and stir to obtain sodium bis-carboxy-sulfonic acid isocyanurate; S2, mixing dextran, anhydrous dimethyl sulfoxide and triethylamine, and passing nitrogen, adding 4-dimethylaminopyridine, p-methoxyphenol and N-acryloyloxy succinimide to react to obtain N-acryloyloxy succinimide esterified dextran, then adding allyl glycidyl ether and anhydrous sodium carbonate to N-acryloyloxy succinimide esterified dextran to react, and then adding sodium 3-mercaptopropionate and azobisisobutyronitrile to react to obtain double-grafted dextran; S3, dispersing acrylamide, maleic anhydride, 2-acrylamido-2-methyl propane sulfonic acid, N,N'-methylene bisacrylamide and ammonium persulfate in deionized water and reacting to obtain a copolymer aqueous solution, then cooling the copolymer aqueous solution and adding formaldehyde solution and dimethylamine aqueous solution to react, adjusting the pH to 11.5-11.8 and adding (3-chloro-2-hydroxypropyl) trimethylammonium chloride aqueous solution to react to obtain a quaternary ammonium ternary copolymer; S4, mixing sodium bis-carboxy-sulfonic acid isocyanurate, double-grafted dextran, quaternary ammonium ternary copolymer, 1,2-benzisothiazolin-3-one, polydimethylsiloxane emulsion, tolyltriazole and deionized water to obtain a low-phosphorus high-efficiency scale inhibition water treatment agent for high-pressure boilers.

2. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S1: The mass-volume ratio of cyanuric acid, dimethyl sulfoxide, p-methoxyphenol, triethylamine and t-butyl acrylate is (13-14) g: 200 mL: (0.2-0.25) g: (2.0-2.5) g: (26-27) g.

3. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S1: The mass-volume ratio of cyanuric acid, 2-ethylsulfonate sodium salt of methacrylic acid and trifluoroacetic acid is (13-14) g: (23-24) g: (40-60) mL.

4. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S2: The mass-volume ratio of dextran, anhydrous dimethyl sulfoxide, triethylamine, 4-dimethylaminopyridine, p-methoxyphenol and N-acryloyloxy succinimide is (10-11) g: 120 mL: (0.5-0.7) mL: 0.12 g: 0.002 g: (2.5-2.7) g.

5. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S2: The mass ratio of dextran, allyl glycidyl ether and anhydrous sodium carbonate is (10-11):(3-3.5):(0.5-0.6).

6. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S2: The mass ratio of dextran, sodium 3-mercaptopropionate and azobisisobutyronitrile is (10-11):(3-3.2):0.

05.

7. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S3: ​ The acrylamide, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, N, N'- methylene bisacrylamide, ammonium persulfate and deionized water (180-185): (23-24): (100-105): 0.5: (5-6):

800.

8. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S3: ​ The mass ratio of the acrylamide, formaldehyde solution, aqueous dimethylamine solution and (3-chloro-2-hydroxypropyl) trimethylammonium chloride aqueous solution is (180-185): (12-13): (17-17.5): (27-28).

9. The process for the preparation of low phosphorus high efficiency scale inhibiting water treatment agent for high pressure boilers as claimed in claim 1 wherein, In S4: ​ The mass ratio of the sodium isocyanurate bixcarboxyl-sulfonic acid, double-grafted dextran, quaternary ammonium terpolymer, 1,2-benzisothiazolin-3-ketone, dimethicone emulsion, tolyltriazole and deionized water is (87-90): (50-55): (375-395): 2: 1: 1:

500.

10. The low-phosphorus high-efficiency scale inhibition water treatment agent for high-pressure boilers prepared by the preparation method according to any one of claims 1-9.

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