Steam turbine circulating water corrosion and scale inhibitor and preparation method thereof

Abstract

The application discloses a steam turbine circulating water corrosion and scale inhibitor and a preparation method thereof. The corrosion and scale inhibitor comprises the following raw materials in parts by mass: a chelating agent 20-35 parts; a polymer corrosion inhibitor 2-5 parts; a bactericide 0.1-1 part; a solubilizer 1-5 parts; and a dispersant 1-3 parts. The polymer corrosion inhibitor is obtained through free radical polymerization of a comonomer, and the comonomer comprises hydrophilic monomers, siloxane monomers, N-vinyl pyrrolidone and vinyl long-chain alkyl ether in a mass ratio of 20-30:10-20:20-40:20-30. The corrosion and scale inhibitor can form a pre-film structure on the surface of equipment through complexing with metal ions on the surface of a circulating system, so that good corrosion inhibition effect is realized while the scale inhibition effect is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of scale inhibitors, in particular to a steam turbine circulating water corrosion and scale inhibitor and a preparation method thereof. BACKGROUND

[0002] The steam turbine is one of the important equipment in power plants, and its circulating water system is crucial to the normal operation of the steam turbine. During the circulating use of the steam turbine, the circulating water mainly plays a role in cooling and lubrication. However, during the continuous circulating use, calcium and magnesium ions gradually accumulate, and oxygen erosion occurs, which causes mineral scaling and corrosion on the surface of the equipment, which not only affects the cooling effect of the steam turbine, but also causes equipment wear and failure. Therefore, solving the problems of circulating water scaling and corrosion is of great significance to ensure the normal operation of the steam turbine and prolong the service life of the equipment.

[0003] The scale and corrosion inhibitors on the market are mainly based on organic phosphine carboxylic acid and carboxylic acid compounds as chelating agents, which form chelates with calcium and magnesium ions to inhibit the deposition and scaling of minerals on the metal surface. However, such scale and corrosion inhibitors have poor inhibitory effect on the corrosion of internal metal equipment, which is not conducive to improving the stability of the circulating water system. SUMMARY

[0004] The present application provides a steam turbine circulating water corrosion and scale inhibitor and a preparation method thereof, which has excellent scale inhibition and corrosion inhibition effects.

[0005] In a first aspect, the present application provides a steam turbine circulating water corrosion and scale inhibitor, which comprises the following raw materials by mass:

[0006] 20-35 parts of a chelating agent;

[0007] 2-5 parts of a polymer corrosion inhibitor;

[0008] 0.1-1 part of a bactericide;

[0009] 1-5 parts of a solubilizing agent;

[0010] 1-3 parts of a dispersing agent;

[0011] The polymer corrosion inhibitor is obtained by free radical polymerization of a comonomer, and the comonomer comprises hydrophilic monomers, siloxane monomers, N-vinyl pyrrolidone, and vinyl long-chain alkyl ether in a mass ratio of 20-30:10-20:20-40:20-30.

[0012] Optionally, the hydrophilic monomers include one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, and N-hydroxymethyl acrylamide.

[0013] Optionally, the siloxane monomer is a siloxane monomer containing unsaturated double bonds.

[0014] Optionally, the siloxane monomer includes one or more of vinyl trimethoxysilane, vinyl triethoxysilane, 3-(methacryloyloxy)propyl trimethoxysilane, and 3-(methacryloyloxy)propyl triethoxysilane.

[0015] Optionally, the vinyl long-chain alkyl ether has a total number of carbon atoms of 10-25.

[0016] Optionally, the vinyl long-chain alkyl ether is one or more of vinyl dodecyl ether, vinyl hexadecyl ether, and vinyl octadecyl ether.

[0017] The polymer corrosion inhibitor of the present application can form a pre-film structure by complexation reaction between the coordination atoms of the pyrrolidone groups in the molecular chain and the metal ions on the surface of the equipment in the circulating water system, and can hinder the electrode reaction and reduce metal corrosion by using the space shielding effect of the macromolecular polymer. At the same time, the long-chain alkyl chain segments in the molecular chain of the corrosion inhibitor improve the hydrophobicity of the pre-film, further reducing the corrosion of water and dissolved oxygen on the metal.

[0018] It should be noted that, in the above copolymerization monomers, the N-vinyl pyrrolidone monomer gives the polymer corrosion inhibitor the ability to complex and connect with the metal surface of the equipment and pipelines; the vinyl long-chain alkyl ether gives the corrosion inhibitor hydrophobicity, improving the corrosion resistance and erosion resistance of the pre-film; the siloxane monomer can bond with the metal surface through the silicon hydroxyl group, improving the adhesion of the pre-film; and the hydrophilic monomer gives the polymer corrosion inhibitor softness and good dispersion in water, ensuring the uniformity of the pre-film. In addition, the hydrophilic monomer used in the present application does not contain carboxyl or amine groups, and is not prone to complexation with calcium and magnesium ions, which is conducive to ensuring the scale inhibition effect.

[0019] Optionally, the corrosion and scale inhibitor further includes 0.3-1 parts of a zinc salt.

[0020] Optionally, the zinc salt is selected from one or more of zinc nitrate, zinc sulfate, zinc chloride, and zinc acetate.

[0021] Optionally, the chelating agent contains polyphosphate, and the polyphosphate accounts for 10-20 wt% of the amount of the chelating agent.

[0022] Optionally, the chelating agent includes ethylenediaminetetraacetic acid, polyphosphate, and polyacrylic acid sodium in a mass ratio of 40-60:10-20:30-40.

[0023] The zinc salt is added in the corrosion and scale inhibitor, which can form hydroxide precipitate film by combining with OH-ions near the cathode (metal surface), increase the cathode polarization, make the potential negative shift, and is beneficial to inhibit the diffusion of rust caused by electric corrosion on the metal surface, and has excellent corrosion inhibition effect. Further, when the chelating agent contains polyphosphate with low stability, phosphate can be obtained by hydrolysis, and phosphate ions and zinc ions can form porous Zn3(PO4)2·4H2O crystal film layer on the metal surface, so that the above-mentioned polymer corrosion inhibitor penetrates into the pores of the crystal film layer, so that the polymer corrosion inhibitor film and the Zn3(PO4)2·4H2O crystal film layer are tightly combined, and a firm double pre-film corrosion structure is formed, and the corrosion and scale inhibition effect is improved. At the same time, Zn3(PO4)2·4H2O or zinc hydroxide precipitate can be combined with pyrrolidone in the pre-film, so that the film layer on the metal surface is more firm and dense, and the scale inhibition and corrosion resistance effect is improved. More importantly, the pyrrolidone group on the pre-film can be combined with the above-mentioned metal hydroxide, thereby forming a firm double protection film structure, and the corrosion inhibition effect is significantly improved.

[0024] The chelating agent composed of ethylenediaminetetraacetic acid, polyphosphate and sodium polyacrylate can chelate with calcium and magnesium metal salts or oxides, and can prevent mineral, bacteria, algae and suspended matter from gathering and settling to form scale through bridging flocculation.

[0025] Optionally, the solubilizing agent includes one or more of ethanol, isopropyl alcohol, ethylene glycol monobutyl ether, dipropylene glycol butyl ether, diethylene glycol butyl ether, and dipropylene glycol methyl ether.

[0026] The above-mentioned solubilizing agent can improve the stability of the corrosion and scale inhibitor during storage and use, and improve the solubility of each effective component in circulating water, especially the solubility of the polymer corrosion inhibitor of the present application.

[0027] Optionally, the bactericide includes one or more of isothiazolinone, benzimidazole methyl carbamate, and sodium hyposulfite.

[0028] Optionally, the dispersing agent includes one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, dodecyl diethanol amide, sodium dodecyl benzene sulfonate, and sodium dodecyl sulfate.

[0029] In a second aspect, the present application provides a preparation method of a steam turbine circulating water corrosion and scale inhibitor, which includes the following steps:

[0030] The emulsifier is added into water, stirred uniformly to obtain an emulsifier solution, the comonomer and the initiator are added, and stirring reaction is carried out at 75-85°C to obtain a polymer corrosion inhibitor;

[0031] The other raw materials are added into the polymer corrosion inhibitor, stirred and mixed uniformly, and then diluted with deionized water to obtain the corrosion and scale inhibitor.

[0032] In summary, the application has the following advantages:

[0033] 1. The corrosion and scale inhibitor of the application is a polymer corrosion inhibitor obtained by polymerization of hydrophilic monomers, siloxane monomers, N-vinyl pyrrolidone and vinyl long-chain alkyl ether, which can form a pre-film with hydrophobic properties on the surface of the metal in the circulating water system by complexing pyrrolidone with the metal surface, effectively isolating water and dissolved oxygen from the metal surface.

[0034] 2. The corrosion and scale inhibitor of the application contains zinc salt and polyphosphate, which can form a porous phosphating film on the surface of the equipment metal, and the polymer corrosion inhibitor can penetrate into the pores of the phosphating film to form a complex pre-film with the metal surface, thereby obtaining a protective layer with a double pre-film corrosion structure, significantly improving the barrier ability of water and oxygen and improving the corrosion and scale inhibition effect. DETAILED DESCRIPTION

[0035] Examples

[0036] In the following examples and comparative examples, some of the raw material parameters are as follows: polyphosphate (molecular weight 1000-1500), sodium polyacrylate (molecular weight 3000-5000).

[0037] Example 1, a steam turbine circulating water corrosion and scale inhibitor, was prepared according to the following steps:

[0038] Polymer corrosion inhibitor preparation: sodium dodecyl benzene sulfonate was added to 850 mL of water and stirred uniformly to obtain an emulsifier solution with a concentration of 3 wt%, 1000 g of copolymer monomers and 20 g of ammonium persulfate were added to the solution, the copolymer monomers included 300 g of hydroxyethyl acrylate, 100 g of 3-(methacryloyloxy) propyl trimethoxysilane, 300 g of N-vinyl pyrrolidone and 300 g of vinyl dodecyl ether, and the reaction was stirred at 82℃ for 4h to obtain the polymer corrosion inhibitor;

[0039] Corrosion and scale inhibitor preparation: 300 g of chelating agent containing 150 g of ethylenediaminetetraacetic acid, 60 g of polyphosphate, 90 g of sodium polyacrylate, 3 g of isothiazolinone, 30 g of isopropyl alcohol, 20 g of fatty alcohol polyoxyethylene ether, 6 g of zinc nitrate and 36 g of polymer corrosion inhibitor were taken, stirred at 500 rpm for 30 min, and uniformly mixed to obtain a mixture; an equal amount of deionized water was added to the mixture and stirred uniformly to obtain the corrosion and scale inhibitor.

[0040] Example 2, a steam turbine circulating water corrosion and scale inhibitor, was prepared according to the following steps:

[0041] Polymer corrosion inhibitor preparation: sodium dodecyl benzene sulfonate was added to 850 mL of water, stirred to obtain a 3wt% emulsifier solution, 1000 g of copolymer monomers and 15 g of ammonium persulfate were added to the solution, the copolymer monomers including 200 g of acrylamide, 100 g of vinyl trimethoxysilane, 400 g of N-vinyl pyrrolidone and 300 g of vinyl dodecyl ether, and the reaction was stirred at 80°C for 4 h to obtain a polymer corrosion inhibitor;

[0042] Corrosion and scale inhibitor preparation: 200 g of chelating agent, including 100 g of ethylenediaminetetraacetic acid, 20 g of polyphosphate, 80 g of sodium polyacrylate, 5 g of isothiazolinone, 10 g of ethanol, 10 g of fatty alcohol polyoxyethylene ether, 4 g of zinc nitrate and 45 g of polymer corrosion inhibitor, were stirred at 500 rpm for 30 min to obtain a mixture; an equal amount of deionized water was added to the mixture and stirred to obtain a corrosion and scale inhibitor.

[0043] Example 3, a steam turbine circulating water corrosion and scale inhibitor, was prepared according to the following steps:

[0044] Polymer corrosion inhibitor preparation: sodium dodecyl benzene sulfonate was added to 850 mL of water, stirred to obtain a 3wt% emulsifier solution, 1000 g of copolymer monomers and 15 g of ammonium persulfate were added to the solution, the copolymer monomers including 200 g of acrylamide, 100 g of vinyl trimethoxysilane, 400 g of N-vinyl pyrrolidone and 300 g of vinyl dodecyl ether, and the reaction was stirred at 80°C for 4 h to obtain a polymer corrosion inhibitor;

[0045] Corrosion and scale inhibitor preparation: 200 g of chelating agent, including 100 g of ethylenediaminetetraacetic acid, 20 g of polyphosphate, 80 g of sodium polyacrylate, 5 g of isothiazolinone, 10 g of ethanol, 10 g of fatty alcohol polyoxyethylene ether, 4 g of zinc nitrate and 45 g of polymer corrosion inhibitor, were stirred at 500 rpm for 30 min to obtain a mixture; an equal amount of deionized water was added to the mixture and stirred to obtain a corrosion and scale inhibitor.

[0046] Table 1, scale inhibitor raw material ratio (g)

[0047]

[0048]

[0049] Example 4, a steam turbine circulating water corrosion and scale inhibitor, differs from example 1 in that an equal amount of polyphosphate is used to replace zinc nitrate in the scale inhibitor preparation step.

[0050] Example 5, a steam turbine circulating water corrosion and scale inhibitor, differs from example 1 in that an equal amount of zinc nitrate is used to replace polyphosphate in the scale inhibitor preparation step.

[0051] Example 6, a steam turbine circulating water corrosion and scale inhibitor, differs from Example 1 in that the same amount of ethylenediaminetetraacetic acid is used to replace polyphosphate in the preparation of the scale inhibitor.

[0052] Comparative Example

[0053] Comparative Example 1, a steam turbine circulating water corrosion and scale inhibitor, differs from Example 6 in that the same amount of methyl methacrylate is used to replace hydroxyethyl acrylate in the preparation of the polymer corrosion inhibitor.

[0054] Comparative Example 2, a steam turbine circulating water corrosion and scale inhibitor, differs from Example 6 in that the same amount of methyl methacrylate is used to replace 3-(methacryloyloxy)propyltrimethoxysilane in the preparation of the polymer corrosion inhibitor.

[0055] Comparative Example 3, a steam turbine circulating water corrosion and scale inhibitor, differs from Example 6 in that the same amount of methyl methacrylate is used to replace vinyl dodecyl ether in the preparation of the polymer corrosion inhibitor.

[0056] Comparative Example 4, a steam turbine circulating water corrosion and scale inhibitor, differs from Example 6 in that the same amount of methyl methacrylate is used to replace N-vinylpyrrolidone in the preparation of the polymer corrosion inhibitor.

[0057] Comparative Example 5, a steam turbine circulating water corrosion and scale inhibitor, differs from Example 6 in that the same amount of 2-phosphonobutane-1,2,4 tricarboxylic acid (organic phosphonic acid corrosion inhibitor) is used to replace the polymer corrosion inhibitor of the present application.

[0058] Performance test

[0059] Test 1: Scale inhibition performance test

[0060] The scale inhibition rate of the corrosion and scale inhibitor in the above examples or comparative examples is determined according to GB / T 16632-2008 “Determination of scale inhibition performance of water treatment agent - calcium carbonate deposition method”. The test time is 10 h, the test water temperature is 80°C, and the dosage of the corrosion and scale inhibitor is 100 mg / L.

[0061] Test 2: Corrosion inhibition performance test

[0062] The corrosion inhibition rate of the corrosion and scale inhibitor in the above examples or comparative examples is evaluated by using a rotating coupon corrosion tester that meets GB / T 18175-2000; the dosage of the corrosion and scale inhibitor is 100 mg / L.

[0063] Table 2, test results

[0064]

[0065] Result analysis:

[0066] (1) According to the combination of Examples 1-6 and Comparative Examples 1-5 and Table 2, it can be seen that the polymer corrosion inhibitor obtained by free radical polymerization of hydrophilic monomers, siloxane monomers, N-vinyl pyrrolidone and vinyl long-chain alkyl ether can significantly slow down the corrosion rate and improve the corrosion inhibition performance without affecting the scale inhibition rate of the corrosion and scale inhibitor of the application. The reason may be that the polymer corrosion inhibitor of the application can form a pre-film structure by complexation reaction of the coordination atoms of the pyrrolidone groups in the molecular chain with the metal ions on the surface of the equipment in the circulating water system, and hinder the electrode reaction by using the space shielding effect of the macromolecular polymer to reduce metal corrosion. At the same time, the hydrophobic effect of the long-chain alkyl group contained therein further improves the barrier ability of the pre-film to water and oxygen, and slows down the metal corrosion.

[0067] (2) According to the combination of Example 1 and Examples 4-6 and Table 2, it can be seen that the addition of zinc salt in the corrosion and scale inhibitor of the application, in combination with the polyphosphate component in the chelating agent, is beneficial to improve the corrosion inhibition rate; and the absence of any one of the two components cannot achieve the best effect. The reason may be that the phosphate ions in the polyphosphate can form a porous phosphating film on the metal surface with zinc ions, and the polymer corrosion inhibitor can penetrate into the microporous structure of the phosphating film and form a chelate to achieve a firmly adhered pre-film, thereby forming a double-layer protective film structure on the metal surface and improving the corrosion inhibition effect.

[0068] The specific embodiments are merely an explanation of the application, and are not a limitation of the application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the application and are protected by the Patent Law.

Claims

1. A corrosion and scale inhibitor for steam turbine circulating water, characterized in that, The raw materials include the following parts by weight: Chelating agent 20-35 parts; 2-5 parts of polymer corrosion inhibitor; 0.1 to 1 part of bactericide; 1-5 parts of solubilizer; 1-3 parts dispersant; 0.3 to 1 part zinc salt; The polymer corrosion inhibitor is obtained by free radical polymerization of comonomers, wherein the comonomers include hydrophilic monomers, siloxane monomers, N-vinylpyrrolidone, and vinyl long-chain alkyl ethers in a mass ratio of 20-30:10-20:20-40:20-30; the chelating agent contains polyphosphate ester, wherein the polyphosphate ester accounts for 10-20 wt% of the chelating agent.

2. The turbine circulating water corrosion and scale inhibitor according to claim 1, characterized in that, The hydrophilic monomer includes one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, and N-hydroxymethylacrylamide.

3. The turbine circulating water corrosion and scale inhibitor according to claim 1, characterized in that, The siloxane monomers include one or more of vinyltrimethoxysilane, vinyltriethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, and 3-(methacryloyloxy)propyltriethoxysilane.

4. The turbine circulating water corrosion and scale inhibitor according to claim 1, characterized in that, The total number of carbon atoms in the vinyl long-chain alkyl ether is 10 to 25.

5. The turbine circulating water corrosion and scale inhibitor according to claim 1, characterized in that, The chelating agent comprises ethylenediaminetetraacetic acid, polyphosphate, and sodium polyacrylate in a mass ratio of 40–60:10–20:30–40.

6. The turbine circulating water corrosion and scale inhibitor according to claim 1, characterized in that, The solubilizer includes one or more of ethanol, isopropanol, ethylene glycol monobutyl ether, dipropylene glycol butyl ether, diethylene glycol butyl ether, and dipropylene glycol methyl ether.

7. The turbine circulating water corrosion and scale inhibitor according to claim 1, characterized in that, The dispersant includes one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, dodecyl diethanolamide, sodium dodecylbenzene sulfonate, and sodium dodecyl sulfate.

8. The method for preparing the turbine circulating water corrosion and scale inhibitor according to any one of claims 1 to 7, characterized in that, Includes the following steps: Emulsifier is added to water and stirred evenly to obtain emulsifier solution. Comonomer and initiator are added and stirred at 75-85℃ to obtain polymer corrosion inhibitor. Other raw materials are added to the polymer slow-release agent, stirred and mixed evenly, and then diluted with deionized water to obtain the corrosion and scale inhibitor.

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