Corrosion and scale inhibitor for TRT and preparation method thereof

Abstract

The present application relates to a kind of corrosion and scale inhibitor for TRT and its preparation method, it is related to chemical reagent technical field, wherein, by mass percentage content, the corrosion and scale inhibitor includes: morpholine 15-20%, aminoethyl ethanolamine 25-30%, 1-hydroxyethyl-2-undecyl imidazolinium salt 15-20%, polyaspartic acid sodium 12-18%, itaconic acid-acrylic sulfonic acid copolymer 8-12%, alkyl glycoside 1-3%, the rest is the mixture of water and glycerol with mass ratio 1:1-3.It is synchronous to inhibit acid medium corrosion and NH4Cl and other salt deposits, effectively improve the corrosion rate and scale inhibition rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical reagents, and particularly relates to an anti-corrosion and anti-fouling agent for TRT and a preparation method thereof. BACKGROUND

[0002] In the blast furnace ironmaking process of the steel industry, the blast furnace gas pressure recovery turbine (hereinafter referred to as "TRT") is the core equipment for realizing energy cascade utilization. By recovering the pressure energy and heat energy contained in the blast furnace top gas, it drives the turbine unit to generate electricity, which can increase the energy utilization rate of blast furnace gas by more than 30%, and the annual power generation capacity of a single device can reach tens of millions of kilowatt-hours. Not only can it significantly reduce the dependence of steel enterprises on external power purchase, but also it meets the core needs of energy saving and consumption reduction in the national industrial field, and has become a standard auxiliary system for modern blast furnaces.

[0003] However, with the upgrading of blast furnace smelting technology towards "high efficiency, low consumption and environmental protection", the wide application of technologies such as oxygen-enriched coal injection, high-reactivity burden (such as pellet) ratio improvement and dry dust removal (such as bag-type dust removal and electric dust removal), the component characteristics of blast furnace gas show a significant trend of complication. On the one hand, although the oxygen-enriched coal injection technology improves the utilization coefficient of the blast furnace, the sulfur and chlorine elements contained in the coal are converted into acidic gaseous impurities such as H2S and HCl in the high-temperature smelting process, resulting in a 2-3 times increase in the concentration of acidic substances in the gas compared with the traditional process. On the other hand, although the dry dust removal technology reduces the dust content in the gas (usually controlled below 10 mg / m³), the residual fine dust (particle size mostly 1-10 μm) has high specific surface area and strong adsorption, which is easy to form complex pollutants with water vapor and acidic impurities in the gas. In addition, the use of high-reactivity burden exacerbates the reduction reaction in the blast furnace, which changes the proportion of combustible components such as H2 and CO in the gas, indirectly affecting the temperature and pressure characteristics of the gas during transportation and expansion.

[0004] The above changes in gas composition directly lead to serious corrosion and fouling problems in the TRT device during operation. The temperature range of the TRT turbine inlet to the working section is 150-350℃, and when the gas expands and works in the turbine, the temperature drops below the dew point (usually 40-80℃). The dissolved H2S, HCl and other acidic gases in the gas will quickly dissolve in the nascent condensed water to form a strong corrosive liquid with a pH value below 4.0. The corrosive liquid adheres to the inner walls of the turbine flow passage, moving blades and static blades, and connecting pipelines, causing an electrochemical corrosion - anodic dissolution (such as Fe→Fe 2+ +2e - ) and cathodic reduction (such as 2H + +2e - →H2↑) primary cell reaction on the surface of the blades, resulting in pitting corrosion and groove corrosion on the surface of the blades, and in severe cases, the wall thickness of the blades can be thinned to less than 70% of the design value, directly threatening the structural safety of the unit.

[0005] NH3 is produced in the process of ammonia desulfurization and nitrogen reduction in the blast furnace, which reacts with H2S and HCl to form ammonium salt components such as NH4Cl and (NH4)2S. Such ammonium salts are easy to reach supersaturation state due to temperature drop in the middle and low temperature section (100-200℃) of the TRT turbine, and precipitate solid crystals with fine dust as crystal nucleus; at the same time, the residual dust particles of Fe2O3, Al2O3 and the like in the coal gas will combine with the precipitated ammonium salt crystals to form a complex scale with a hardness of 500HV or more. After the scale adheres to the surface of the rotor, it will damage the dynamic balance precision of the rotor, cause the vibration value of the unit to increase, trigger the shutdown protection; in addition, the scale will also block the turbine flow passage, reduce the coal gas flow area, cause the power generation efficiency of the unit to decrease, and accelerate the blade wear, shorten the blade replacement cycle from 3 years to 1.5 years or less.

[0006] At present, although various technical means including process control, online flushing and the like have been applied to solve the above problems, these methods will interfere with the stability of the blast furnace operation, and also increase the system energy consumption and maintenance cost. In comparison, the addition of corrosion and scale inhibitors in the coal gas is considered as a more feasible comprehensive treatment approach due to its simple operation, strong adaptability and no influence on power generation efficiency. However, the traditional water-based agents can only play a role after the formation of corrosive condensate, and there is a blind area of protection. And the conventional agents often focus on the single function of corrosion inhibition or scale inhibition, or are simply compounded, and there is lack of synergy between the components, or even mutual interference. For example, strong acid environment will make some scale inhibitors ineffective, and some corrosion inhibitors are powerless to salt scale. Water-soluble corrosion inhibitors are difficult to distribute in the gas phase, and volatile corrosion inhibitors are insufficient in the aqueous phase, and some organic components will decompose at high temperature.

[0007] Therefore, it has become an urgent technical requirement for energy saving and consumption reduction and long-term operation of equipment in the current steel industry to develop a new type of TRT special corrosion and scale inhibitor which can effectively inhibit corrosion and effectively block the formation of scale. SUMMARY

[0008] In order to solve the above technical problems, the present application provides a corrosion and scale inhibitor for TRT and a preparation method thereof. The corrosion and scale inhibitor of the present application can simultaneously inhibit the corrosion of acidic medium and the salt scale such as NH4Cl, and effectively improve the corrosion inhibition rate and scale inhibition rate.

[0009] In a first aspect, the present application provides an inhibitor and scale inhibitor for TRT, which comprises, in terms of mass percentage: morpholine 15-20%, aminoethylethanolamine 25-30%, 1-hydroxyethyl-2-undecyl imidazolinium salt 15-20%, polyaspartic acid sodium 12-18%, itaconic acid-acrylsulfonic acid copolymer 8-12%, alkyl glycoside 1-3%, and the balance being a mixture of water and glycerol in a mass ratio of 1:1-3.

[0010] In the above technical solution, morpholine is used as a gas-phase neutralizing agent, which is a volatile cyclic secondary amine. Due to its high volatility, it can rapidly diffuse throughout the TRT flow channel along with the coal gas flow. Before condensation occurs, it can react with acidic gases such as H2S and HCl in the coal gas: C4H9ONH + HCl → C4H9ONH2 + Cl — , thereby reducing the concentration of acidic gases in the gas phase and reducing the corrosiveness. At the same time, it ensures that the pH value of the nascent condensate formed when the temperature drops below the dew point is not too low, greatly alleviating the corrosiveness of the liquid phase.

[0011] Aminoethylethanolamine is an organic amine containing primary amine (-NH2), secondary amine (-NH-), and hydroxyl (-OH), and has good water solubility. Its volatility is not as high as that of morpholine, and it can continuously provide neutralization capacity in a wider temperature range, making up for the consumption of morpholine at low temperatures. The primary amine group (-NH2) in the molecule is a strong coordination group that can form a coordination bond with iron atoms on the metal surface through chemical adsorption, providing a favorable interface environment for the adsorption of imidazolinium salt. The two work together to form a more dense and more stable protective film, enhancing the stability and coverage of the film.

[0012] 1-hydroxyethyl-2-undecyl imidazolinium salt has a polar quaternary ammonium nitrogen atom and a long-chain hydrophobic alkyl group. In the aqueous phase, the positively charged quaternary ammonium nitrogen cation (N+) is quickly adsorbed on the metal surface (such as Fe, Cu, etc.) which is usually negatively charged through strong electrostatic attraction, achieving initial protection. The long-chain undecyl group on the metal surface is oriented and arranged to form a hydrophobic physical barrier, effectively separating water, chloride ions, oxygen, and other corrosive media from the metal body, while inhibiting the corrosion-related charge transfer process.

[0013] Polyaspartic acid sodium, as a non-phosphorus scale inhibitor and dispersant, has a large number of carboxyl groups (-COO-) on its molecular chain. Its long molecular chain can embed into the crystal lattice of growing NH4Cl, CaCO3, and other microcrystals, causing distortion of the crystals. The distorted crystals cannot grow and accumulate normally, and thus become loose and fragile, making it difficult for them to form a hard and dense scale layer on the leaf surface. The carboxyl groups are adsorbed on the surface of microcrystals and dust particles through electrostatic repulsion, preventing them from colliding and aggregating.

[0014] Itaconic acid-acrylsulfonic acid copolymer as high temperature scale inhibition dispersant, containing carboxyl (-COO-) and strong polar sulfonic acid group (-SO3-). The introduction of sulfonic acid group, makes it in high temperature, high ionic strength and in a wider pH range, not easy to degrade failure. Sulfonic acid group on Fe2O3, Al2O3 and other metal oxide dust has a strong adsorption capacity, can effectively prevent these hard particles into scale crystal nucleus or with ammonium salt combined to form a complex scale.

[0015] Alkyl glycoside as a biological surfactant, can significantly reduce the surface tension of the liquid, so that it can form smaller, more uniform droplets in the atomization device, increase the contact area with the gas, thereby promoting the gasification of amine and uniform distribution of the reagent in the gas phase. At the same time, it can significantly improve the wettability and spreadability of the liquid on the metal surface, ensure that the corrosion inhibitor composition can effectively cover every micro corner on the surface of the blade, eliminate the coverage blind area caused by surface tension, and make the protective film more complete and uniform.

[0016] Glycerol not only dissolves each component as a solvent, but also forms hydrogen bonds with the molecules of corrosion inhibitor and scale inhibitor, enhancing the stability of the reagent at high temperature. At the same time, the water absorption of glycerol can adjust the viscosity of the reagent, ensuring uniform particle size during atomization and mixing with coal gas.

[0017] Optionally, the preparation method of the itaconic acid-acrylsulfonic acid copolymer comprises the following steps: itaconic acid and sodium acrylsulfonate with a mass ratio of 1:1-1.5 are added to deionized water and stirred to prepare a solution with a mass concentration of 30-40%, and then slowly heated to 60-70°C to completely dissolve the monomers, and then an appropriate amount of sodium hydroxide solution is used to adjust the pH value of the system to 4-5, and then 5-10% of isopropyl alcohol based on the total mass of itaconic acid and sodium acrylsulfonate is added to the solution, nitrogen is introduced for 15-20 min, the temperature is raised to 85-90°C, and then ammonium persulfate is slowly added under stirring, the mass ratio of isopropyl alcohol to ammonium persulfate is 1.5-3:1, and then incubated for 1-2 h, and finally cooled to below 40°C to obtain a light yellow to amber transparent viscous liquid, which is the itaconic acid-acrylsulfonic acid copolymer.

[0018] In the above technical solution, adjusting the pH to weakly acidic can convert part of itaconic acid to sodium itaconate, which can effectively inhibit the formation of itaconic anhydride from itaconic acid under strong acidic conditions.

[0019] Oxygen is an effective inhibitor of free radical polymerization. Oxygen reacts with primary free radicals to form inert species. Nitrogen is introduced to create an oxygen-free environment, improving the efficiency of the polymerization reaction.

[0020] Ammonium persulfate decomposes under heat to produce sulfate anion radicals: S2O8 2-→ 2·SO4-. It can attack the double bond of monomer molecules, activate them, form monomer radicals, and thus initiate the chain. Monomer radicals continue to react with other monomer molecules, so the chain continues to lengthen. Itaconic acid provides carboxyl groups, and sodium allylsulfonate provides sulfonic acid groups, both of which are embedded in the long polymer chain. Slowly adding ammonium persulfate can control the reaction rate, avoid the reaction from being too fast, and prevent the instantaneous generation of too many free radicals, thereby ensuring that the molecular weight distribution is uniform. The role of isopropyl alcohol is to control the molecular weight. Isopropyl alcohol will react with the growing polymer chain radicals, making them terminate, while generating a new active radical. This effectively inhibits the unlimited growth of molecular weight, prevents the formation of insoluble gel, and ensures that the corrosion and scale inhibitor is water-soluble and has a moderate molecular weight polymer. The growing chain radicals collide with each other or with residual radicals, leading to chain termination and the formation of stable polymer molecules.

[0021] Alternatively, the preparation method of the 1-hydroxyethyl-2-undecyl imidazolinium salt comprises the following steps: condensation and cyclization of undecanoic acid and hydroxyethyl ethylenediamine at 150-160°C in the presence of a catalyst for 4-6h to obtain a 1-hydroxyethyl-2-undecyl imidazoline intermediate; quaternary ammonium reaction of the 1-hydroxyethyl-2-undecyl imidazoline intermediate with dimethyl sulfate in a solvent at a temperature of 60-80°C for 3-5h to obtain the 1-hydroxyethyl-2-undecyl imidazolinium salt.

[0022] In the above technical solution, the carboxyl group of undecanoic acid undergoes nucleophilic substitution with the primary amine group of hydroxyethyl ethylenediamine, and the catalyst complexes with the carboxyl oxygen to enhance the electrophilicity of the carboxyl carbon, accelerating the reaction to generate undecanoic acid monohydroxyethyl ethylenediamine amide. The amide nitrogen atom has one lone pair of electrons, and the secondary amine group within the hydroxyethyl ethylenediamine molecule has nucleophilicity. At high temperatures, the secondary amine group within the hydroxyethyl ethylenediamine molecule undergoes nucleophilic substitution with the amide carbon again, forming a double bond (C=N) between the nitrogen and carbon, and together with the carbon atoms at both ends, forming a five-membered ring, i.e. an imidazoline ring. One of the nitrogen atoms on the imidazoline ring has a pair of lone pair electrons, and the methyl carbon in dimethyl sulfate is affected by the electron-withdrawing effect of the sulfur atom, carrying a partial positive charge. The nitrogen atom of the imidazoline reacts with the methyl carbon of the dimethyl sulfate through nucleophilic substitution, and the methyl group (-CH3) is transferred to the nitrogen atom, while the O-S bond is broken to generate a methyl sulfite anion. After the nitrogen atom is connected with the methyl group, a quaternary ammonium cation is formed, which pairs with the methyl sulfite anion to form an ionic compound, quaternary ammonium salt.

[0023] Optionally, the catalyst is boric acid or p-toluene sulfonic acid, the solvent is a mixture of water and isopropyl alcohol with a mass ratio of 1:1-2; the molar ratio of the undecanoic acid, hydroxyethyl ethylenediamine and the catalyst is 1:1-1.5:0.005-0.01, and the molar ratio of the 1-hydroxyethyl-2-undecyl imidazoline intermediate and dimethyl sulfate is 1:1-1.2.

[0024] In the above technical solution, the viscosity of the imidazoline product is very large, and the addition of the solvent can reduce the viscosity of the system to ensure uniform mixing and mass transfer. At the same time, the solvent as a reaction medium can disperse the reaction heat to prevent local overheating.

[0025] Optionally, the corrosion and scale inhibitor further comprises 0.5-1.5% of vinyl triethoxysilane by mass percentage.

[0026] In the above technical solution, after the vinyl triethoxysilane is put into the aqueous phase, the ethoxyl group (-OC2H5) thereof will be rapidly hydrolyzed to generate a highly reactive silanol. The silanol molecules will be adsorbed on the surface of metal oxides (such as Fe2O3 and Cr2O3 on the surface of turbine blades) through van der Waals force.

[0027] The -OH group on the silanol reacts with the hydroxyl group on the metal surface to form a stable Si-O-M covalent bond (M represents Fe, Cr and the like). At the same time, adjacent silanol molecules will also condense to form a network structure of Si-O-Si-, thereby forming a silane film on the metal surface. The hydrophobic long chain of the 1-hydroxyethyl-2-undecyl imidazolinium salt can be tightly combined with the hydrophobic part of the silane film through van der Waals force. The cationic head group of the 1-hydroxyethyl-2-undecyl imidazolinium salt is electrostatically attracted to the negative center existing in the silane film to form a dense and firm composite protective film.

[0028] In a second aspect, the present application provides a preparation method of a corrosion and scale inhibitor for TRT, which comprises the following steps:

[0029] The mixture of water and glycerol is heated to 40-50°C, morpholine and aminoethyl ethanolamine are slowly added, stirred at this temperature for 15-20 min, then sodium polyaspartate is added, stirred until completely dissolved, then the itaconic acid-acrylsulfonic acid copolymer is slowly added, stirred for 30-40 min until completely dissolved, the temperature of the reaction kettle is reduced to room temperature, 1-hydroxyethyl-2-undecyl imidazolinium salt is added, slowly stirred for 20-30 min, finally the alkyl glycoside is added and stirred for 40-60 min, and then aged for 10-14 h to obtain the corrosion and scale inhibitor.

[0030] In the above technical solution, heating and stirring at 40-50°C can reduce the viscosity of glycerol, promote rapid and uniform mixing of water and glycerol. Slow stirring at this temperature can ensure that the more volatile morpholine is uniformly dispersed and dissolved in the solvent, rather than escaping due to vaporization.

[0031] The molecular weight of sodium polyaspartate is relatively small and easy to dissolve. Adding it first can provide better medium conditions for the subsequent dissolution of the polymer. Slowly adding itaconic acid-propene sulfonic acid copolymer and giving sufficient time for stirring can ensure that the high polymer molecular chain is fully stretched and hydrated. If it is added too quickly or not stirred enough, the surface of the polymer particles will swell rapidly and stick together, forming a gel that is difficult to dissolve, resulting in uneven final product and reduced efficiency. 1-hydroxyethyl-2-undecyl imidazolinium salt is unstable at higher temperatures (>50°C) and will decompose, resulting in loss of corrosion inhibition efficiency. Adding it at a lower temperature can protect the integrity of its molecular structure.

[0032] As a surfactant, alkyl glycoside can further reduce the surface tension of the entire system and promote more uniform dispersion of all previously added components.

[0033] Optionally, the preparation method further comprises adding alkyl glycoside and continuing to stir for 40-60 min, and finally slowly adding vinyl triethoxysilane dropwise, with the dropwise addition time controlled at 10-15 min, and allowing it to stand and age for 10-14 h to obtain the corrosion and scale inhibitor.

[0034] In the above technical solution, silane will hydrolyze in water. Slowly adding and thoroughly stirring is to control the hydrolysis rate, so that it initially generates a reactive silanol, but without a local concentration that is too high to cause a large amount of condensation and form insoluble siloxane particles, thereby ensuring the clarity and stability of the corrosion and scale inhibitor.

[0035] In summary, the present application includes at least one of the following beneficial technical effects:

[0036] 1. By adding 1-hydroxyethyl-2-undecyl imidazolinium salt, the positively charged quaternary ammonium nitrogen cation (N+) in the aqueous phase is quickly adsorbed on the metal surface (such as Fe, Cu, etc.) which is usually negatively charged through strong electrostatic attraction, achieving initial protection. The long-chain undecyl group is oriented on the metal surface, forming a hydrophobic physical barrier that effectively separates water, chloride ions, oxygen, and other corrosive media from the metal body, while inhibiting the corrosion-related charge transfer process.

[0037] 2. By adding itaconic acid-propylene sulfonic acid copolymer, the introduction of sulfonic acid group makes it not easy to degrade and fail in high temperature, high ionic strength and wide pH range. Sulfonic acid group has strong adsorption capacity for metal oxide dust such as Fe2O3 and Al2O3, which can effectively prevent these hard particles from becoming the crystal nucleus of scale or combining with ammonium salt to form composite scale.

[0038] 3. By adding morpholine, due to its high volatility, it can quickly spread to the entire TRT flow channel with the flow of coal gas. Before condensation occurs, it can react with H2S, HCl and other acidic gases in the coal gas to neutralize, reducing the concentration of acidic gases in the gas phase and reducing the corrosiveness.

[0039] 4. By adding aminoethyl ethanolamine, it continuously provides neutralization capacity in a wide temperature range, making up for the consumption of morpholine at low temperature. The primary amine group (-NH2) in the molecule is a strong coordination group that can form a coordination bond with iron atoms on the metal surface through chemical adsorption, providing a favorable interface environment for the adsorption of imidazolinium salt. The two work together to form a denser and more stable protective film, enhancing the stability and coverage of the film. DETAILED DESCRIPTION

[0040] The application will be further described in detail below in combination with examples.

[0041] The materials used in the following examples can be obtained by market purchase.

[0042] Example 1: This example discloses an inhibitor and scale inhibitor #1 for TRT and a preparation method thereof.

[0043] An inhibitor and scale inhibitor for TRT, by mass percentage, the inhibitor and scale inhibitor comprises: morpholine 15%, aminoethyl ethanolamine 25%, 1-hydroxyethyl-2-undecyl imidazoline onium salt 15%, polyaspartic acid sodium 12%, itaconic acid-propylene sulfonic acid copolymer 8%, alkyl glycoside 1%, and the rest is a mixture of water and glycerol with a mass ratio of 1:3.

[0044] The preparation method comprises the following steps:

[0045] S1, preparation of itaconic acid-propylene sulfonic acid copolymer:

[0046] The itaconic acid and sodium allyl sulfonate with a mass ratio of 1:1.2 were stirred in deionized water to prepare a solution with a mass concentration of 35%, and then slowly heated to 65°C to completely dissolve the monomers. Then, the pH value of the system was adjusted to 4.6 by adding an appropriate amount of sodium hydroxide solution. Then, 8% of isopropyl alcohol based on the total mass of itaconic acid and sodium allyl sulfonate was added to the solution, and nitrogen was introduced for 17 min. The temperature was raised to 90°C, and ammonium persulfate was slowly added under stirring. The mass ratio of isopropyl alcohol to ammonium persulfate was 2.3:1, and the temperature was kept for 1.5 h. Finally, the temperature was cooled to below 40°C to obtain a light yellow to amber transparent viscous liquid, which was the itaconic acid-allyl sulfonic acid copolymer.

[0047] S2, Preparation of 1-hydroxyethyl-2-undecyl imidazolinium salt:

[0048] S21, in the presence of boric acid, undecanoic acid and hydroxyethyl ethylenediamine were subjected to condensation and cyclization reaction at 155°C for 5 h, and the molar ratio of undecanoic acid, hydroxyethyl ethylenediamine and boric acid was 1:1.2:0.008, to obtain 1-hydroxyethyl-2-undecyl imidazoline intermediate;

[0049] S22, the 1-hydroxyethyl-2-undecyl imidazoline intermediate was subjected to quaternary ammonium reaction with dimethyl sulfate in a mixture of water and isopropyl alcohol with a mass ratio of 1:1-2 at a temperature of 70°C for 4 h, and the molar ratio of 1-hydroxyethyl-2-undecyl imidazoline intermediate to dimethyl sulfate was 1:1.1, to obtain the 1-hydroxyethyl-2-undecyl imidazolinium salt.

[0050] S3, Preparation of corrosion and scale inhibitor:

[0051] The mixture of water and glycerol was heated to 45°C, and morpholine and aminoethyl ethanolamine were slowly added. Stirring was carried out at this temperature for 17 min, and then sodium polyaspartate was added. After stirring until completely dissolved, itaconic acid-allyl sulfonic acid copolymer was slowly added. Stirring was carried out for 35 min until completely dissolved. The temperature of the reaction kettle was reduced to room temperature, and 1-hydroxyethyl-2-undecyl imidazolinium salt was added. Slow stirring was carried out for 25 min, and finally alkyl glycoside was added and stirring was continued for 50 min. After standing and aging for 12 h, corrosion and scale inhibitor #1 was obtained.

[0052] Example 2: This example discloses a corrosion and scale inhibitor for TRT and a preparation method thereof.

[0053] A corrosion and scale inhibitor for TRT, which comprises, in terms of mass percentage: morpholine 20%, aminoethyl ethanolamine 30%, 1-hydroxyethyl-2-undecyl imidazolinium salt 20%, sodium polyaspartate 18%, itaconic acid-allyl sulfonic acid copolymer 12%, alkyl glycoside 3%, and the balance is a mixture of water and glycerol with a mass ratio of 1:1.

[0054] The preparation method of the corrosion and scale inhibitor is the same as that of example 1.

[0055] Example 3: This example discloses a corrosion and scale inhibitor #3 for TRT and a preparation method thereof.

[0056] A corrosion and scale inhibitor for TRT, in terms of mass percentage, the corrosion and scale inhibitor comprises: morpholine 18%, aminoethyl ethanolamine 27%, 1-hydroxyethyl-2-undecyl imidazolinium salt 18%, polyaspartic acid sodium 15%, itaconic acid-acrylsulfonic acid copolymer 10%, alkyl glycoside 2%, and the balance is a mixture of water and glycerol in a mass ratio of 1:2.

[0057] The preparation method of the corrosion and scale inhibitor is the same as that of example 1.

[0058] Example 4: This example discloses a corrosion and scale inhibitor #4 for TRT and a preparation method thereof.

[0059] A corrosion and scale inhibitor for TRT, in terms of mass percentage, the corrosion and scale inhibitor comprises: morpholine 18%, aminoethyl ethanolamine 27%, 1-hydroxyethyl-2-undecyl imidazolinium salt 18%, polyaspartic acid sodium 15%, itaconic acid-acrylsulfonic acid copolymer 10%, alkyl glycoside 2%, and the balance is a mixture of water and glycerol in a mass ratio of 1:2.

[0060] S1, preparation of itaconic acid-acrylsulfonic acid copolymer:

[0061] Itaconic acid and sodium acrylsulfonate in a mass ratio of 1:1.2 are added to deionized water and stirred to prepare a solution with a mass concentration of 35%, and then slowly heated to 65°C to completely dissolve the monomers, and then the pH value of the system is adjusted to 4.5 by adding an appropriate amount of sodium hydroxide solution, and then 8% of isopropyl alcohol based on the total mass of itaconic acid and sodium acrylsulfonate is added to the solution, nitrogen is introduced for 17 min, the temperature is raised to 90°C, and then ammonium persulfate is slowly added dropwise under stirring, the mass ratio of isopropyl alcohol to ammonium persulfate is 2.3:1, and then the system is incubated for 1.5 h, and finally cooled to below 40°C to obtain a transparent viscous liquid with a light yellow to amber color, which is itaconic acid-acrylsulfonic acid copolymer.

[0062] S2, preparation of 1-hydroxyethyl-2-undecyl imidazolinium salt:

[0063] S21, in the presence of boric acid, undecanoic acid and hydroxyethyl ethylenediamine are subjected to condensation and cyclization reaction at 155°C for 5 h, the molar ratio of undecanoic acid, hydroxyethyl ethylenediamine and boric acid is 1:1.2:0.008, to obtain 1-hydroxyethyl-2-undecyl imidazoline intermediate;

[0064] S22, quaternization of the 1-hydroxyethyl-2-undecyl imidazoline intermediate with dimethyl sulfate in a mixture of water and isopropyl alcohol at a mass ratio of 1:1-2 for 4 h at a temperature of 70 °C, the molar ratio of 1-hydroxyethyl-2-undecyl imidazoline intermediate to dimethyl sulfate is 1:1.1, to obtain the 1-hydroxyethyl-2-undecyl imidazolinium salt.

[0065] S3, preparation of the corrosion and scale inhibitor:

[0066] The mixture of water and glycerol is heated to 45 °C, morpholine and aminoethyl ethanolamine are slowly added, stirred at this temperature for 17 min, then sodium polyaspartate is added, stirred until completely dissolved, then itaconic acid-acrylsulfonic acid copolymer is slowly added, stirred for 35 min until completely dissolved, the temperature of the reaction kettle is reduced to room temperature, 1-hydroxyethyl-2-undecyl imidazolinium salt is added, slowly stirred for 25 min, then alkyl glycoside is added and continues to stir for 50 min, finally vinyl triethoxysilane is slowly added dropwise, the dropwise time is controlled at 10-15 min, and aged for 12 h to obtain the corrosion and scale inhibitor #4.

[0067] Comparative Example 1: This comparative example provides a comparative corrosion and scale inhibitor D1, which is the same as Example 4, except that N-methyl morpholine is used instead of morpholine.

[0068] Comparative Example 2: This comparative example provides a comparative corrosion and scale inhibitor D2, which is the same as Example 4, except that triethanolamine is used instead of aminoethyl ethanolamine.

[0069] Comparative Example 3: This comparative example provides a comparative corrosion and scale inhibitor D3, which is the same as Example 4, except that benzotriazole is used instead of 1-hydroxyethyl-2-undecyl imidazolinium salt.

[0070] Comparative Example 4: This comparative example provides a comparative corrosion and scale inhibitor D4, which is the same as Example 4, except that hydrolyzed polymaleic anhydride is used instead of sodium polyaspartate.

[0071] Comparative Example 5: This comparative example provides a comparative corrosion and scale inhibitor D5, which is the same as Example 4, except that maleic acid-acrylic acid copolymer is used instead of itaconic acid-acrylsulfonic acid copolymer.

[0072] Comparative Example 6: This comparative example provides a comparative corrosion and scale inhibitor D6, which is the same as Example 4, except that sucrose ester is used instead of alkyl glycoside.

[0073] The corrosion and scale inhibitors #1-#4 of Examples 1-4 of the present invention and the comparative corrosion and scale inhibitors D1-D6 of Comparative Examples 1-6 were subjected to performance tests, including scale inhibition performance tests, corrosion inhibition performance tests, and iron oxide dispersion performance tests. The performance test results are shown in Tables 1-3.

[0074] I. Scale Inhibition Performance Test

[0075] (a) In Ca 2+ Concentration of 2000 mg / L, SO4 2- In a solution with a concentration of 480 mg / L, corrosion and scale inhibitor samples from the examples and comparative examples of this application were added at a dosage of 50 mg / L. The solution was then allowed to stand at 80°C for 10 hours. The blank group did not contain any corrosion and scale inhibitor sample. After cooling to room temperature, the solution was filtered, and the Ca concentration in the filtrate was determined by EDTA titration. 2+ The concentration was tested, and the scale inhibition rate was calculated using the following formula: T / % = [(K2-K1) / (K0-K1)] × 100%, where T is the scale inhibition rate; K0 is the Ca in the original solution. 2+ Concentration; K1 is the Ca concentration in the filtrate of the blank group. 2+ Concentration; K2 is the Ca in the filtrate after treatment with the corrosion and scale inhibitor sample. 2+ concentration.

[0076] (ii) According to the solubility curve of NH4Cl, its solubility at 80°C is approximately 65.6 g / 100 g water. To ensure sufficient supersaturation, a stock solution with a concentration of 600 g / L is prepared.

[0077] Accurately weigh approximately 150.0 g of NH4Cl into a 250 mL stoppered conical flask and add 100 mL of deionized water. Add the corrosion and scale inhibitor samples from the examples and comparative examples of this application, respectively, at a dosage of 50 mg / L. Then, allow the mixture to stand at 80 °C for 10 h. The blank group, without the addition of corrosion and scale inhibitor, is placed in an 80 °C constant temperature water bath and continuously stirred or intermittently shaken to ensure complete dissolution of NH4Cl and the reagent, resulting in a clear and transparent supersaturated solution. Remove the completely dissolved conical flask from the water bath and allow it to stand at room temperature for 10 h. After filtration, the NH4Cl in the filtrate was tested by weighing. The scale inhibition rate was calculated using the following formula: SIR(%)=[(M0-M1) / M0]×100%, where SIR: scale inhibition rate of NH4Cl; M0: mass of NH4Cl scale precipitated in the blank group (g); M0=mass of the filter membrane after filtration - mass of the blank filter membrane; M1: mass of NH4Cl scale precipitated in the experimental group (dosing group) (g).

[0078] Table 1

[0079] Example performance CaSO4 scale inhibition rate (%) NH4Cl scale inhibition rate (%) Example 1 96.84 93.96 Example 2 97.01 94.22 Example 3 97.53 94.37 Example 4 98.78 95.65 Comparative Example 1 90.17 88.45 Comparative Example 2 91.62 87.93 Comparative Example 3 88.52 85.63 Comparative Example 4 90.39 88.73 Comparative Example 5 89.99 88.74 Comparative Example 6 93.72 90.47

[0080] II. Corrosion Inhibition Performance Test

[0081] Referring to GBT18175 "Determination of Corrosion Inhibition Performance of Water Treatment Agent by Rotating Hanging Piece Method", a corrosive condensate similar to the composition of the initial condensation zone of the TRT turbine is prepared, and the metal test piece is immersed therein, and the rotating hanging piece test is carried out at a constant temperature. By measuring the corrosion weight loss of the test piece under the conditions of adding and not adding the drug, the corrosion inhibition rate is calculated.

[0082] Table 2

[0083] Example performance Inhibition rate (mm·a -1 ])]] Example 1 0.0552 Example 2 0.0483 Example 3 0.0347 Example 4 0.0154 Comparative Example 1 0.0753 Comparative Example 2 0.0694 Comparative Example 3 0.0874 Comparative Example 4 0.0725 Comparative Example 5 0.0920 Comparative Example 6 0.0611

[0084] III. Performance test of dispersed iron oxide

[0085] In the solution with the concentration of 150 mg / L of Al 2+ The mixed corrosion and scale inhibitor sample is added to the solution with the concentration of 10 mg / L of Fe 2+ The mixed corrosion and scale inhibitor sample is added to the solution with the concentration of 10 mg / L of Fe

[0086] IV. Heat stability test

[0087] A certain amount of corrosion and scale inhibitor sample is placed in a high-temperature-resistant and well-sealed container, and the container is placed in a constant-temperature oven or muffle furnace. After being treated at 120°C for 24 hours, the retention rate of scale inhibition rate and corrosion inhibition rate is tested.

[0088] The calculation formula is as follows: performance retention rate (%) = (performance of sample after aging / original sample performance) x 100%.

[0089] V. Biodegradability test

[0090] Referring to GBT21856-2008 "Chemical Rapid Biodegradability CO2 Generation Test", under the condition of aeration, the amount of organic carbon in the sample is converted into CO2 under the action of microorganisms. By measuring the amount of generated CO2 compared with the theoretical CO2 generation amount, the biodegradation rate is obtained.

[0091] Table 3

[0092] Example performance Light transmittance (%) ​ Corrosion inhibition rate retention (%) Biodegradability (%) Example 1 30.7 95.2 96.4 80.5 Example 2 30.1 95.5 96.7 80.5 Example 3 29.5 96.6 97.3 81.7 Example 4 28.4 97.5 98.4 82.9 Comparative Example 1 44.2 90.7 91.6 78.4 Comparative Example 2 42.8 91.4 91.8 79.6 Comparative Example 3 53.3 89.1 90.7 76.9 Comparative Example 4 57.5 90.3 91.5 77.7 Comparative Example 5 55.1 90.4 91.2 78.5 Comparative Example 6 41.7 92.9 93.3 75.1

[0093] From the data of examples 1-3 in tables 1-3, especially the data of example 3, it can be seen that by reasonable matching of the corrosion and scale inhibitor of the present application, the corrosion and scale inhibitor of the present application performs more excellent in scale inhibition performance, corrosion inhibition performance, dispersed iron oxide performance, heat stability, biodegradability, etc.

[0094] Compared with Example 3, vinyltriethoxysilane was added to the corrosion and scale inhibitor in Example 4, and the performance of the obtained corrosion and scale inhibitor #4 was slightly higher than that of the corrosion and scale inhibitor #3. This is because the ethoxyl group (-OC2H5) of the vinyltriethoxysilane will be rapidly hydrolyzed to form a highly reactive silanol after being put into the aqueous phase. The silanol molecules will be adsorbed on the surface of metal oxides (such as Fe2O3 and Cr2O3 on the surface of turbine blades) through van der Waals force. The -OH group on the silanol molecule will undergo dehydration condensation reaction with the hydroxyl group on the metal surface to form a stable Si-O-M covalent bond (M represents Fe, Cr and the like). At the same time, adjacent silanol molecules will also condense to form a network structure of Si-O-Si-, thereby forming a silane film on the metal surface. The hydrophobic long chain of the 1-hydroxyethyl-2-undecylimidazolium salt can be closely combined with the hydrophobic part of the silane film through van der Waals force. The cationic head group of the 1-hydroxyethyl-2-undecylimidazolium salt is electrostatically attracted to the negative center existing in the silane film to form a dense and firm composite protective film.

[0095] Compared with Example 4, N-methylmorpholine was selected instead of morpholine in Comparative Example 1, and the performance of the obtained comparative corrosion and scale inhibitor D1 was not as good as that of the corrosion and scale inhibitor #4. This is because although N-methylmorpholine and morpholine have similar structures, one H on the ring of N-methylmorpholine is replaced by a methyl group. The introduction of the methyl group makes it difficult for the lone pair of electrons on the nitrogen atom to approach the acid gas molecules (such as HCl), resulting in a significantly lower neutralization reaction rate and efficiency than morpholine.

[0096] Compared with Example 4, triethanolamine was selected instead of aminoethyl ethanolamine in Comparative Example 2, and the performance of the obtained comparative corrosion and scale inhibitor D2 was not as good as that of the corrosion and scale inhibitor #4. This is because triethanolamine contains three hydroxyl groups and a tertiary amine nitrogen, but the nitrogen atom is a tertiary amine without lone pair of electrons available for forming covalent coordination bond, so it cannot chemisorb on the metal surface to form a protective film, but only can provide weak neutralization and pH buffering effect. The primary amine group (-NH2) in the aminoethyl ethanolamine molecule is a strong coordination group, which can form a coordination bond with the iron atoms on the metal surface through chemical adsorption, thereby providing a favorable interface environment for the adsorption of imidazolium salt.

[0097] Compared with Example 4, benzotriazole was selected instead of 1-hydroxyethyl-2-undecylimidazolium salt in Comparative Example 3, and the performance of the obtained comparative corrosion and scale inhibitor D3 was not as good as that of the corrosion and scale inhibitor #4. This is because the benzotriazole molecule is small and lacks long-chain alkyl groups, and although it can form a monomolecular chemical adsorption film on the metal surface, it cannot provide an effective hydrophobic physical barrier. Its film focuses more on changing the electrochemical properties of the metal, rather than forming a physical barrier through long-chain alkyl groups to isolate the corrosion medium like the 1-hydroxyethyl-2-undecylimidazolium salt.

[0098] Compared with example 4, the hydrolyzed polymaleic anhydride is selected instead of sodium polyaspartate in the comparative example 4, and the performances of the obtained comparative corrosion and scale inhibitor D4 are all not as good as those of the corrosion and scale inhibitor #4, because the degradation of the hydrolyzed polymaleic anhydride is not as good as that of the sodium polyaspartate. In high-alkalinity and high-hardness water, the hydrolyzed polymaleic anhydride is unstable in performance, resulting in performance decline. The peptide bond structure of the sodium polyaspartate makes the performance more stable under different water quality conditions.

[0099] Compared with example 4, the maleic acid-acrylic acid copolymer is selected instead of itaconic acid-propylene sulfonic acid copolymer in the comparative example 5, and the performances of the obtained comparative corrosion and scale inhibitor D5 are all not as good as those of the corrosion and scale inhibitor #4, because the cyclic structure of the maleic acid needs to be hydrolyzed to become a carboxyl group after polymerization, and the rigidity of the molecular chain is stronger than that of the itaconic acid, and the double-carboxyl structure constructed by the itaconic acid is not effective.

[0100] Compared with example 4, the sucrose ester is selected instead of the alkyl glycoside in the comparative example 6, and the performances of the obtained comparative corrosion and scale inhibitor D6 are all not as good as those of the corrosion and scale inhibitor #4, because the ester bond of the sucrose ester is relatively easy to hydrolyze under high temperature or extreme pH conditions, resulting in failure. The ether bond of the alkyl glycoside has excellent chemical stability and acid and alkali resistance, and can better adapt to the pH fluctuation and residual temperature conditions existing in the TRT system.

[0101] Therefore, the replaced material cannot play a role in the corrosion and scale inhibitor, but reduces the role of the corrosion and scale inhibitor, and therefore each component cannot be replaced by other materials at will.

[0102] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, and therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A corrosion and scale inhibitor for TRT, characterized in that, The corrosion and scale inhibitor comprises, in terms of mass percentage, 15-20% of morpholine, 25-30% of aminoethyl ethanolamine, 15-20% of 1-hydroxyethyl-2-undecyl imidazoline onium salt, 12-18% of polyaspartic acid sodium, 8-12% of itaconic acid-acrylsulfonic acid copolymer, 1-3% of alkyl glycoside, and the balance of a mixture of water and glycerol at a mass ratio of 1:1-3; The preparation method of the itaconic acid-acrylsulfonic acid copolymer comprises the following steps: itaconic acid and sodium acrylsulfonate at a mass ratio of 1:1-1.5 are added to deionized water for stirring, a solution with a mass concentration of 30-40% is prepared, and the solution is slowly warmed to 60-70°C to completely dissolve the monomers, an appropriate amount of sodium hydroxide solution is used to adjust the pH value of the system to 4-5, then 5-10% of isopropyl alcohol of the total mass of itaconic acid and sodium acrylsulfonate is added to the solution, nitrogen is introduced for 15-20 min, the temperature is warmed to 85-90°C, ammonium persulfate is slowly added dropwise under stirring, the mass ratio of isopropyl alcohol to ammonium persulfate is 1.5-3:1, and the solution is incubated for 1-2 h, and finally the solution is cooled to below 40°C to obtain a light yellow to amber transparent viscous liquid, which is the itaconic acid-acrylsulfonic acid copolymer; The preparation method of the 1-hydroxyethyl-2-undecyl imidazoline onium salt comprises the following steps: undecanoic acid and hydroxyethyl ethylenediamine are subjected to condensation cyclization reaction at 150-160°C in the presence of a catalyst for 4-6 h to obtain a 1-hydroxyethyl-2-undecyl imidazoline intermediate; the 1-hydroxyethyl-2-undecyl imidazoline intermediate is subjected to quaternary ammonium reaction with dimethyl sulfate in a solvent at 60-80°C for 3-5 h to obtain the 1-hydroxyethyl-2-undecyl imidazoline onium salt; the catalyst is boric acid or p-toluenesulfonic acid, and the solvent is a mixture of water and isopropyl alcohol at a mass ratio of 1:1-2; the molar ratio of undecanoic acid, hydroxyethyl ethylenediamine and the catalyst is 1:1.2:0.008, and the molar ratio of the 1-hydroxyethyl-2-undecyl imidazoline intermediate to dimethyl sulfate is 1:1.

1.

2. The corrosion and scale inhibitor for TRT according to claim 1, characterized in that, The corrosion and scale inhibitor further comprises 0.5-1.5% of vinyl triethoxysilane in terms of mass percentage.

3. A method for preparing the corrosion and scale inhibitor for TRT according to any one of claims 1-2, characterized in that, The preparation method comprises the following steps: The mixture of water and glycerol is heated to 40-50°C, morpholine and aminoethyl ethanolamine are slowly added, stirring is performed at this temperature for 15-20 min, then polyaspartic acid sodium is added, stirring is performed until complete dissolution, then itaconic acid-acrylsulfonic acid copolymer is added, stirring is performed for 30-40 min until complete dissolution, the temperature of the reaction kettle is reduced to room temperature, 1-hydroxyethyl-2-undecyl imidazoline onium salt is added, slow stirring is performed for 20-30 min, finally alkyl glycoside is added and stirring is continued for 40-60 min, and aging is performed for 10-14 h to obtain the corrosion and scale inhibitor.

4. The method for preparing the corrosion and scale inhibitor for TRT according to claim 3, characterized in that, The preparation method further comprises adding alkyl glycoside and continuing stirring for 40-60 min, finally slowly adding vinyl triethoxysilane dropwise, the dropwise adding time is controlled to 10-15 min, and aging is performed for 10-14 h to obtain the corrosion and scale inhibitor.