A boiler feed water scale inhibitor and a method of making the same

Abstract

The application discloses a boiler feed water scale inhibitor and a preparation method thereof. The scale inhibitor comprises the following raw materials in percentage by mass: scale and corrosion inhibition copolymer 40-60%, reverse osmosis scale inhibition polymer 30-50%, and corrosion inhibitor 10-20%. The reverse osmosis scale inhibition polymer is prepared by the following method: free radical copolymerization of epoxy acrylate monomer, hydroxy acrylate and sulfonic acid group-containing olefin monomer in a mass ratio of 20-30:30-50:40-50 to prepare intermediate A; polycondensation of dibasic amine and dibasic acid to obtain intermediate B; and amidation reaction of intermediate A and intermediate B to obtain the reverse osmosis scale inhibition polymer. The application can effectively solve the problem that the traditional reverse osmosis scale inhibitor has poor surface affinity with the polyamide reverse osmosis membrane, is difficult to form a stable protective layer, is easy to be desorbed and invalid under water flow scouring, and causes membrane flux loss.

Description

Technical Field

[0001] This application relates to the field of scale inhibitors for water treatment, and in particular to a scale inhibitor for boiler feedwater and its preparation method. Background Technology

[0002] As a core component of thermal power generation, the boiler feedwater system of steam turbines directly impacts the operational safety and thermal efficiency of the unit. This feedwater primarily consists of condensate recovered from the turbine condenser and supplemental demineralized water. After mixing, the two undergo multiple purification processes to meet boiler feedwater standards. Reverse osmosis (RO) membrane separation technology is widely used in desalination due to its high desalination capacity, effectively removing total dissolved solids (TDS), colloidal, and ionic impurities from the water. However, during RO treatment, as the feedwater becomes increasingly concentrated, insoluble salts (such as CaCO3, CaSO4, and silicates) formed by the combination of hardness ions like calcium and magnesium with carbonate and sulfate ions tend to precipitate and deposit on the membrane surface, forming a dense scale layer. This leads to a significant decrease in membrane flux, increased operating pressure, and in severe cases, irreversible blockage of the membrane elements.

[0003] To suppress scaling in reverse osmosis systems, existing technologies generally employ the method of adding scale inhibitors to the feed water side, delaying the crystallization and precipitation of scale-forming salts through chelation and dispersion. For example, Chinese patent CN107261855A discloses a composite scale inhibitor for water with high hardness and high sulfate content. It uses polyamino-polyether methylene phosphonic acid as the main agent, combined with butenoic acid-acrylamide-hydroxypropyl acrylate copolymer and sodium ethylenediaminetetramethylene phosphonate, utilizing the synergistic effect of each component to improve the scale inhibition rate against calcium sulfate and calcium carbonate. While this technology solves the membrane fouling problem under high salinity water to some extent, the scale inhibitor molecules lack affinity with the polyamide reverse osmosis membrane surface, making it difficult to form a stable protective layer. Under high-speed water flow, it is prone to desorption and failure, requiring continuous excessive dosage to maintain its effect, further exacerbating the system corrosion risk and economic costs. Summary of the Invention

[0004] This application provides a boiler feedwater scale inhibitor and its preparation method, which can effectively solve the problem that traditional reverse osmosis scale inhibitors have poor affinity with the surface of polyamide reverse osmosis membranes, making it difficult to form a stable protective layer, and are prone to desorption and failure under water flow, resulting in membrane flux loss.

[0005] In a first aspect, this application provides a boiler feedwater scale inhibitor, comprising the following raw materials by mass percentage: 40-60% scale and corrosion inhibitor copolymer, 30-50% reverse osmosis scale inhibitor polymer, and 10-20% corrosion inhibitor; the reverse osmosis scale inhibitor polymer is prepared by the following method: free radical copolymerization of epoxy acrylate monomers, hydroxy acrylates, and sulfonic acid-containing olefin monomers in a mass ratio of 20-30:30-50:40-50 to prepare intermediate A; condensation polymerization of diamine and diacid to obtain intermediate B; and amidation reaction of intermediate A and intermediate B to obtain the final product.

[0006] In any of the above technical solutions, the epoxy acrylate monomer is selected from glycidyl methacrylate and / or allyl alcohol glycidyl ether.

[0007] In any of the above technical solutions, the hydroxyacrylate is selected from any one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, and hydroxybutyl acrylate.

[0008] In any of the above technical solutions, the alkene monomer containing sulfonic acid group is selected from any one or more of sodium styrene sulfonate, sodium allyl sulfonate, sodium methacrylate sulfonate, and sodium 2-acrylamide-2-methylpropanesulfonate.

[0009] In any of the above technical solutions, the molar ratio of the diamine to the diacid is 1.1 to 1.3:1.

[0010] In any of the above technical solutions, the mass ratio of intermediate A to intermediate B is 6-10:5-8.

[0011] In any of the above technical solutions, the dicarboxylic acid is selected from any one or more of 2,6-pyridinedicarboxylic acid, 3,4-pyridinedicarboxylic acid, 2,2-bipyridine-4,4-dicarboxylic acid, and 2,2'-bipyridine-3,3'-dicarboxylic acid.

[0012] In any of the above technical solutions, the diamine is selected from any one or more of ethylenediamine, pentanediamine, hexanediamine, or decanediamine.

[0013] In any of the above technical solutions, the reaction temperature of the polycondensation reaction is 140-180°C, and the reaction time is 8-10 hours.

[0014] In any of the above technical solutions, the amidation reaction time is 80–95°C.

[0015] The reverse osmosis antiscalant polymer of this application achieves high affinity with the surface of polyamide reverse osmosis membranes, forming a stable protective layer that is not easily desorbed or fails under high-speed water flow. Firstly, the free radical copolymerization of epoxy acrylate monomers endows the polymer with active epoxy groups. These groups can bond with active amino groups on the surface of the polyamide reverse osmosis membrane, forming a covalent anchoring effect, significantly improving the adhesion stability of the antiscalant on the membrane surface and preventing desorption failure caused by high-speed water flow. Hydroxyacrylates and sulfonic acid-containing olefin monomers enhance molecular hydrophilicity through ether bond hydration, improving the self-cleaning ability of the membrane surface and reducing the physical adsorption of fouling. The sulfonic acid groups of sulfonic acid-containing olefin monomers (such as sodium 2-acrylamido-2-methylpropanesulfonate) provide strong electronegativity, dispersing scale particles through electrostatic repulsion while chelating Ca2+. 2+ Mg 2+ Plasma inhibits the growth of crystal nuclei, thus preventing scale formation.

[0016] It is worth noting that in the polycondensation of diamines and pyridine-containing dicarboxylic acids, by controlling the excess of diamine, the polycondensation product intermediate B retains the terminal amine group (-NH2), which efficiently bonds with the carboxyl group of intermediate A in the subsequent amidation reaction. The rigid heterocyclic structure of pyridine dicarboxylic acid monomers has both steric hindrance and coordination functions—its pyridine nitrogen atom can strongly complex metal ions and block the active sites of the crystal lattice, while the bipyridine skeleton hinders the migration of crystal nuclei to the membrane pores and inhibits the accumulation of stubborn scale such as CaSO4 and silicates.

[0017] In any of the above technical solutions, the raw materials of the scale and corrosion inhibitor copolymer include the following parts by weight of comonomers: 40-60 parts of unsaturated carboxylic acid monomer, 20-30 parts of polyethylene glycol monomethyl ether acrylate, and 20-40 parts of allyl phosphate diethyl ester.

[0018] In traditional scale inhibitor formulations, a high proportion of phosphonic acids readily hydrolyzes to form phosphate ions, which react with Fe... 3+ Ca 2+ The combination of these substances forms secondary scale, accelerating pitting and stress corrosion cracking of metal pipe walls, causing structural damage to turbine blades and boiler heat transfer surfaces. The scale-inhibiting and corrosion-inhibiting copolymer of this application possesses both scale-inhibiting and corrosion-inhibiting properties, and effectively solves the industry problem of traditional phosphonic acid scale inhibitors accelerating metal corrosion through hydrolysis.

[0019] Specifically, the carboxyl groups of unsaturated carboxylic acid monomers interfere with scale crystallization through lattice distortion, while the long-chain ether oxygen structure of polyethylene glycol monomethyl ether acrylate promotes copolymer dissolution and dispersion through hydrophilic effects. The key lies in the introduction of allyl phosphate diethyl ester, whose phosphate ester group (-PO(OEt)2) exists as a high-molecular-weight side chain. Compared to small-molecule phosphonic acid scale inhibitors, its CP bond hydrolytic stability is significantly improved, effectively preventing PO4 from forming. 3-This reduces the risk of secondary scaling caused by the release of harmful substances; simultaneously, the P=O bonds coordinate with the passivation layer on the metal surface to form a dense organic pre-film, blocking dissolved oxygen and Cl-. - The corrosion path.

[0020] In any of the above technical solutions, the unsaturated carboxylic acid monomer is selected from any one or more of acrylic acid, methacrylic acid, maleic acid, and itaconic acid.

[0021] In any of the above technical solutions, the corrosion inhibitor is any one or more of benzotriazole, mercaptobenzothiazole, and hexadecylamine.

[0022] Secondly, this application provides a method for preparing a boiler feedwater scale inhibitor, which involves mixing a scale inhibitor and corrosion inhibitor copolymer, a reverse osmosis scale inhibitor polymer, and a corrosion inhibitor according to the raw material ratio of any of the scale inhibitors described above.

[0023] In any of the above technical solutions, the dosage of the boiler feedwater scale inhibitor is 3-12g per ton of water.

[0024] In summary, this application has the following beneficial effects:

[0025] The reverse osmosis antiscaling polymer of this application covalently bonds epoxy groups to the polyamide membrane, providing a durable protective layer on the membrane surface. Combined with the coordination blocking ability of pyridine dicarboxylic acid-terminated amine polyamide, it effectively inhibits the tendency of membrane scaling under high hardness water. The scale and corrosion inhibitor copolymer, relying on the structural stability of allyl diethyl phosphate, forms a metal corrosion inhibitor pre-film while inhibiting scale formation, and is further enhanced by benzotriazole corrosion inhibitors to protect metal equipment. This scale inhibitor, with a low dosage of 3–12 g / ton of water, simultaneously achieves long-term scale prevention of the reverse osmosis membrane and corrosion control of the boiler system, providing technical assurance for the safe operation of high-parameter units. It also systematically improves the efficiency of boiler feedwater treatment. Detailed Implementation

[0026] Preparation Example

[0027] Preparation Example 1-1: A reverse osmosis antiscalant polymer was prepared by the following steps:

[0028] 250g of glycidyl methacrylate, 400g of hydroxyethyl acrylate, and 450g of sodium 2-acrylamido-2-methylpropanesulfonate were added to a reaction vessel and dissolved in 2200mL of deionized water. Nitrogen gas was purged for 30min to remove oxygen. The temperature was raised to 75℃, and then ammonium persulfate aqueous solution (1.5% of the total monomer mass) was added dropwise over 1 hour. The reaction was maintained at this temperature for 3 hours to obtain intermediate A. Separately, 220g of 2,2'-bipyridine-4,4'-dicarboxylic acid and 66g of ethylenediamine were polycondensed at 160℃ for 9 hours under reduced pressure (0.08MPa) and nitrogen protection to obtain intermediate B. 600g of intermediate A and 500g of intermediate B were dissolved in N,N-dimethylformamide, and 5g of 4-dimethylaminopyridine catalyst was added. The reaction was carried out at 90℃ for 6 hours. Small molecules were removed by dialysis, and the product was spray-dried to obtain a white powder.

[0029] Preparation Examples 1-2: A reverse osmosis antiscalant polymer was prepared by the following steps:

[0030] 210g of allyl alcohol glycidyl ether, 330g of hydroxypropyl methacrylate, and 400g of sodium styrene sulfonate were added to a reaction vessel and dissolved in 2000mL of deionized water. Nitrogen gas was purged for 30min to remove oxygen. The temperature was raised to 73℃, and then ammonium persulfate aqueous solution (1.2% of the total monomer mass) was added dropwise over 1 hour. The reaction was maintained at this temperature for 4 hours to obtain intermediate A. Separately, 200g of 3,4-pyridinedicarboxylic acid and 78g of pentanediamine were polycondensed at 140℃ for 10 hours under reduced pressure (0.08MPa) and nitrogen protection to obtain intermediate B. 600g of intermediate A and 500g of intermediate B were dissolved in N,N-dimethylformamide, and 4g of 4-dimethylaminopyridine catalyst was added. The reaction was carried out at 80℃ for 8 hours. Small molecules were removed by dialysis, and the product was spray-dried to obtain a white powder.

[0031] Preparation Examples 1-3: A reverse osmosis antiscalant polymer was prepared by the following steps:

[0032] 290g of glycidyl methacrylate, 480g of hydroxyethyl methacrylate, and 500g of sodium allyl sulfonate were added to a reaction vessel and dissolved in 2500mL of deionized water. Nitrogen gas was purged for 30min to remove oxygen, and the temperature was raised to 80℃. Azobisisobutyronitrile (2.0% of the total monomer mass) was added, and the reaction was maintained at this temperature for 3.5h to obtain intermediate A. Separately, 220g of 2,2'-bipyridine-4,4'-dicarboxylic acid and 66g of ethylenediamine were polycondensed at 160℃ for 9h under reduced pressure (0.08MPa) and nitrogen protection to obtain intermediate B. 600g of intermediate A and 500g of intermediate B were dissolved in N,N-dimethylformamide, and 5g of 4-dimethylaminopyridine catalyst was added. The reaction was carried out at 95℃ for 4h. Small molecules were removed by dialysis, and the product was spray-dried to obtain a white powder.

[0033] Preparation Examples 1-4, a reverse osmosis antiscalant polymer, differs from Preparation Example 1-1 in that 2,2'-bipyridine-4,4'-dicarboxylic acid (220 g) is replaced with an equimolar amount of adipic acid (131.6 g).

[0034] Preparation Examples 1-5: A reverse osmosis antiscalant polymer was prepared by the following steps:

[0035] 250g of glycidyl methacrylate, 400g of hydroxyethyl acrylate, and 450g of sodium 2-acrylamide-2-methylpropanesulfonate were added to a reaction vessel and dissolved in 2200mL of deionized water. Nitrogen gas was purged for 30 minutes to remove oxygen. The temperature was raised to 75℃, and then an aqueous solution of ammonium persulfate (1.5% of the total monomer mass) was added dropwise over 1 hour. The reaction was maintained at this temperature for 3 hours to obtain intermediate A.

[0036] 600g of intermediate A and 500g of polyetheramine (GA2-2000, molecular weight 2000, functionality 2) were dissolved in N,N-dimethylformamide, and 5g of 4-dimethylaminopyridine catalyst were added. The mixture was subjected to amidation at 90℃ for 6 hours. Small molecules were removed by dialysis, and the product was spray-dried to obtain a white powder.

[0037] Preparation Examples 1-6, a reverse osmosis antiscalant polymer, differ from Preparation Example 1-1 in that intermediate A is used as the final product and no subsequent preparation steps are performed.

[0038] Preparation Examples 1-7, a reverse osmosis antiscalant polymer, differ from Preparation Examples 1-6 in that glycidyl methacrylate is replaced with an equal mass of hydroxyethyl methacrylate.

[0039] Preparation Example 2-1: A scale and corrosion inhibitor copolymer was prepared by the following method:

[0040] Add 500g itaconic acid, 250g polyethylene glycol monomethyl ether acrylate (MPEG-500), and 350g diethyl allyl phosphate to a reaction vessel, followed by 1650mL of deionized water. Purge with nitrogen for 30 minutes, raise the temperature to 78℃, and then add ammonium persulfate (2.0% of the total monomer mass) as an initiator solution dropwise over 3 hours. Maintain the reaction temperature for 3 hours, then add isopropanol (5% of the total monomer mass) as a chain transfer agent to control the molecular weight. After cooling, dialyze and concentrate by rotary evaporation to obtain the final product.

[0041] Preparation Example 2-2: A scale and corrosion inhibitor copolymer was prepared by the following method:

[0042] Add 420g maleic acid, 210g polyethylene glycol monomethyl ether acrylate (MPEG-350), and 250g diethyl allyl phosphate to a reaction vessel, followed by 1050mL of deionized water. Purge with nitrogen for 30 minutes, raise the temperature to 80℃, and then add potassium persulfate (1.5% of the total monomer mass) initiator solution dropwise over 3 hours. Maintain the reaction temperature for 3 hours, then add isopropanol (3% of the total monomer mass) as a chain transfer agent to control the molecular weight. After cooling, dialyze and concentrate by rotary evaporation to obtain the final product.

[0043] Preparation Examples 2-3: A scale and corrosion inhibitor copolymer was prepared by the following method:

[0044] Add 580g of acrylic acid, 290g of polyethylene glycol monomethyl ether acrylate (MPEG-600), and 450g of diethyl allyl phosphate to a reaction vessel, followed by 2300mL of deionized water. Purge with nitrogen for 30 minutes, raise the temperature to 82℃, and then add potassium persulfate (2.5% of the total monomer mass) initiator solution dropwise over 3 hours. Maintain the reaction temperature for 2.5 hours, and then add mercaptoethanol (3% of the total monomer mass) as a chain transfer agent to control the molecular weight. After cooling, dialyze and concentrate by rotary evaporation to obtain the final product.

[0045] Preparation Example 2-4, a scale and corrosion inhibitor copolymer, differs from Preparation Example 2-1 in that an equal mass of acrylic acid is used instead of diethyl allyl phosphate.

[0046] Example

[0047] Example 1: A boiler feedwater scale inhibitor is prepared by adding 50g of the scale and corrosion inhibitor copolymer of Preparation Example 2-1, 40g of the reverse osmosis scale inhibitor polymer of Preparation Example 1-1, and 10g of benzotriazole into a stirred tank and mixing at 500 rpm for 20 minutes.

[0048] Example 2: A boiler feedwater scale inhibitor is prepared by adding 40g of the scale and corrosion inhibitor copolymer of Preparation Example 2-2, 40g of the reverse osmosis scale inhibitor polymer of Preparation Example 1-2, and 20g of mercaptobenzothiazole into a stirred tank and mixing at 300 rpm for 20 minutes.

[0049] Example 3: A boiler feedwater scale inhibitor is prepared by adding 60g of the scale and corrosion inhibitor copolymer of Preparation Examples 2-3, 30g of the reverse osmosis scale inhibitor polymer of Preparation Examples 1-3, 5g of benzotriazole, and 5g of hexadecylamine into a stirred tank and mixing at 500 rpm for 30 minutes.

[0050] Example 4, a boiler feedwater scale inhibitor, differs from Example 1 in that the reverse osmosis scale inhibitor polymer of Preparation Examples 1-4 is replaced with the reverse osmosis scale inhibitor polymer of Preparation Example 1-1 in equal mass.

[0051] Example 5, a boiler feedwater scale inhibitor, differs from Example 1 in that the scale and corrosion inhibitor copolymer of Preparation Example 2-4 is replaced with an equal mass of the scale and corrosion inhibitor copolymer of Preparation Example 2-1.

[0052] Example 6, a boiler feedwater scale inhibitor, differs from Example 1 in that an equal mass of sodium ethylenediaminetetramethylenephosphonate is used to replace the scale and corrosion inhibitor copolymer in Preparation Example 2-1. Comparative Example

[0053] Comparative Example 1, a boiler feedwater scale inhibitor, differs from Example 6 in that the reverse osmosis scale inhibitor polymer of Preparation Examples 1-5 is replaced with the reverse osmosis scale inhibitor polymer of Preparation Example 1-1 in equal mass.

[0054] Comparative Example 2, a boiler feedwater scale inhibitor, differs from Example 6 in that the reverse osmosis scale inhibitor polymer of Preparation Examples 1-6 is replaced with the reverse osmosis scale inhibitor polymer of Preparation Example 1-1 by means of equal mass.

[0055] Comparative Example 3, a boiler feedwater scale inhibitor, differs from Example 6 in that the reverse osmosis scale inhibitor polymer of Preparation Examples 1-7 is replaced with the reverse osmosis scale inhibitor polymer of Preparation Examples 1-1 in equal mass.

[0056] Comparative Example 4, a boiler feedwater scale inhibitor, differs from Example 6 in that an equal mass of commercially available reverse osmosis scale inhibitor (BA-600) replaces the reverse osmosis scale inhibitor polymer of Preparation Example 1-1.

[0057] Performance testing

[0058] Experiment 1: Scale Inhibition Performance Test of Reverse Osmosis Membrane

[0059] Reference standard: HG / T 5166-2017 "Evaluation method for scale inhibition performance of reverse osmosis antiscalant".

[0060] Test water preparation: Ca 2+ 800 mg / L (calculated as CaCO3), Mg 2+ 500mg / L, HCO3 - 1000 mg / L, SO4 2- :1200mg / L, Si02:50mg / L, pH=8.0±0.2.

[0061] Sample preparation: The scale inhibitors of Examples 1-7 and Comparative Examples 1-3 were dissolved in the test water at a dosage of 8g / ton of water.

[0062] Test conditions: Reverse osmosis membrane: polyamide composite membrane (model BW30-400); operating pressure: 1.5 MPa; temperature: 25℃; concentration ratio: 4 times; circulation cycle: 12 h; total duration: 72 h. Membrane flux decay rate monitoring: permeate flow rate was recorded every 2 h, and the flux decay rate (%) was calculated as follows: = (initial flux - final flux) / initial flux × 100%

[0063] Experiment 2: Scale inhibition and corrosion inhibition performance of metal surfaces

[0064] Reference standard: HG / T 5166-2017 Appendix to Corrosion Inhibition Performance Test (Rotating Plaque Method)

[0065] Samples and media: 20# carbon steel (boiler tubes) and H62 brass (turbine blades) were used as metal test pieces. The test water quality was the same as that of the reverse osmosis test water (with 10 mg / L Fe³⁺ added to simulate a corrosive environment).

[0066] Test conditions: temperature 80℃, rotation speed 75rpm, time 72h, scale inhibitor dosage: 12g / ton of water (maximum design value).

[0067] Test indicators: Scale inhibition rate (%) = (Scale amount of blank group - Scale amount of test group) / Scale amount of blank group × 100%; Corrosion inhibition rate (%) = (Corrosion rate of blank group - Corrosion rate of test group) / Corrosion rate of blank group × 100%.

[0068] Table 1. Performance Test Results

[0069]

[0070] Analysis of experimental results:

[0071] (1) Analysis of scale inhibition performance of reverse osmosis membrane (membrane flux decline rate)

[0072] The membrane flux decline rates of Examples 1-3 were significantly lower than those of Example 4. This may be because Example 4 used adipic acid to replace pyridine dicarboxylic acid (Preparation Examples 1-4), resulting in the loss of the metal coordination ability of pyridine amine and the inability to block Ca. 2+ The movement of metal ions and crystal nuclei into the membrane pores.

[0073] Furthermore, the membrane flux decline in Comparative Examples 1-4 was higher than that in Examples 1-3. This may be because Comparative Example 1 used polyetheramine instead of polyamide (Preparation Examples 1-5), and Comparative Example 2 used ungrafted polyamide (Preparation Examples 1-6), both of which weakened the affinity and intermolecular forces between the reverse osmosis antiscalant polymer and the polyamide membrane, making it difficult to form a stable protective layer. Comparative Example 3 used an epoxy-free intermediate A (Preparation Examples 1-7), which could not covalently bond with the polyamide membrane, and the physical adsorption layer was easily washed away and desorbed.

[0074] (2) Analysis of scale inhibition performance of metal surfaces (scale inhibition rate)

[0075] The scale inhibition rate of carbon steel in Examples 1-3 was significantly better than that in Examples 6 and 7 (70.8%). This may be because the scale and corrosion inhibitor copolymer in Example 6 lacked allyl diethyl phosphate (Preparation Examples 2-4), resulting in a significantly deteriorated ability to form a pre-film with the metal complex; and Example 7 used a small-molecule phosphonic acid compound, which is easily hydrolyzed to produce PO4. 3- This can lead to secondary scaling.

[0076] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A boiler feed water scale inhibitor characterized by, The raw material comprises the following mass percentages: scale and corrosion inhibition copolymer 40-60%, reverse osmosis scale inhibition polymer 30-50%, corrosion inhibitor 10-20%; the reverse osmosis scale inhibition polymer is prepared by the following method: free radical copolymerization of epoxy acrylate monomer, hydroxy acrylate and sulfonic acid group-containing olefin monomer in a mass ratio of 20-30:30-50:40-50 to prepare intermediate A; polycondensation of dibasic amine and dibasic acid in a molar ratio of 1.1-1.3:1 to obtain intermediate B; amidation reaction of intermediate A and intermediate B in a mass ratio of 6-10:5-8 to obtain the reverse osmosis scale inhibition polymer; the dibasic acid is selected from any one or more of 2,6-pyridine dicarboxylic acid, 3,4-pyridine dicarboxylic acid, 2,2-bipyridine-4,4-dicarboxylic acid and 2,2'-bipyridine-3,3'-dicarboxylic acid; the raw material of the scale and corrosion inhibition copolymer comprises the following mass parts of copolymerized monomers: unsaturated carboxylic acid monomer 40-60 parts, polyethylene glycol monomethyl ether acrylate 20-30 parts, allyl phosphoric acid diethyl ester 20-40 parts; the corrosion inhibitor is any one or more of benzotriazole, mercaptobenzothiazole and hexadecylamine.

2. The scale inhibitor of claim 1, wherein, The epoxy acrylate monomer is selected from glycidyl methacrylate and / or allyl glycidyl ether.

3. The scale inhibitor of claim 1, wherein, The sulfonic acid group-containing olefin monomer is selected from any one or more of styrene sodium sulfonate, allyl sodium sulfonate, sodium methacrylate sulfonate and 2-acrylamide-2-methylpropane sulfonic acid sodium.

4. The scale inhibitor of claim 1, wherein, The dibasic amine is selected from any one or more of ethylenediamine, pentanediamine, hexanediamine and decanediamine.

5. A method of preparing a boiler feed water scale inhibitor, characterized by, The raw material of the scale inhibitor according to any one of claims 1-4 is mixed uniformly to obtain the scale and corrosion inhibition copolymer, the reverse osmosis scale inhibition polymer and the corrosion inhibitor.

Images