Compound corrosion inhibitor for power plant boiler shutdown protection and preparation method and application thereof

Abstract

The application discloses a compounded corrosion inhibitor for power plant boiler shutdown protection, a preparation method and application, wherein the compounded corrosion inhibitor comprises a solvent and a corrosion inhibitor body; the solvent is water; the corrosion inhibitor body comprises octadecylamine, dodecylamine, hexadecylamine, N-octyl-1,3-propylene diamine and a surfactant. On the basis of the traditional octadecylamine shutdown protection agent, the dodecylamine, hexadecylamine and N-octyl-1,3-propylene diamine for improving the liquid phase film forming property are added, and the surfactant for improving the low-temperature film forming property is added, so that the compounded corrosion inhibitor can form a uniform protective film on the metal surface of the whole water vapor system through the joint action of different components; the compounded corrosion inhibitor has good corrosion inhibition performance on the boiler steel in the gas phase and the liquid phase, in the low-temperature and high-temperature regions, can form a uniform and dense protective film on the surface of the carbon steel, and has good protection effect.

Description

Technical Field

[0001] This invention belongs to the field of corrosion inhibitor technology, and relates to a compound corrosion inhibitor for the protection of power plant boilers during shutdown, its preparation method, and its application. Background Technology

[0002] During the shutdown and standby period of power plant thermal equipment, the large influx of air and the humid environment inside the thermal system make the metal surfaces of unprotected or improperly protected thermal equipment highly susceptible to corrosion. This shutdown corrosion has the following hazards: firstly, it has a wide corrosion range and a high corrosion rate; secondly, it can exacerbate operational corrosion of the thermal equipment. Corrosion occurring in unprotected thermal equipment during shutdown is often more severe than during operation.

[0003] To prevent or control metal corrosion when thermal equipment is shut down, appropriate protective measures are essential. Currently, there are many commonly used methods for protecting thermal equipment during shutdown, including maintaining feedwater pressure, maintaining steam pressure, nitrogen purging, and ammonia purging to prevent air ingress; drying, desiccant, and dehumidifier methods to reduce relative humidity; and octadecylamine and vapor phase corrosion inhibitor methods using corrosion-inhibiting chemicals.

[0004] Octadecylamine has been used for shutdown protection in domestic power plants for many years, and many power plants have adopted this technology. Under suitable conditions, octadecylamine can form a protective film on the surface of boiler steel, providing good protection for the boiler system. However, when using octadecylamine for shutdown protection, there are certain requirements for the concentration of octadecylamine used, the film-forming temperature, and the film-forming time. For example, the optimal film-forming temperature is around 220℃, and the optimal film-forming concentration is around 25 mg / L. The octadecylamine protection method has disadvantages such as poor film-forming effect at low temperatures and poor film-forming effect in the liquid phase.

[0005] In view of the above, there is an urgent need to develop a new corrosion inhibitor for the protection of power plant boilers during shutdown. This inhibitor should have good corrosion inhibition performance on boiler steel in both gas and liquid phases, as well as in low and high temperature regions. The protective film formed on the carbon steel surface should be uniform and dense, providing good protection. Summary of the Invention

[0006] To address the aforementioned deficiencies in existing technologies, the present invention aims to provide a compound corrosion inhibitor for boiler shutdown protection in power plants, along with its preparation method and application. Based on the traditional octadecylamine shutdown protection agent, this invention adds dodecylamine, hexadecylamine, and N-oleo-1,3-propanediamine to improve liquid-phase film-forming properties, and a surfactant to improve low-temperature film-forming properties. Through the combined action of these different components, the compound corrosion inhibitor can form a uniform protective film on the metal surface of the entire steam-water system. The compound corrosion inhibitor of this invention exhibits good corrosion inhibition performance on boiler steel in both the gas and liquid phases, as well as in low and high temperature regions. It can form a uniform and dense protective film on carbon steel surfaces, providing excellent protection.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of the present invention provides a compound corrosion inhibitor for the protection of power plant boilers during shutdown, comprising a solvent and a corrosion inhibitor body; the solvent is water; the corrosion inhibitor body comprises octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine and a surfactant.

[0009] Preferably, in the compound corrosion inhibitor, the mass percentage concentration of the corrosion inhibitor body is 8-12 wt%.

[0010] Preferably, the compound corrosion inhibitor comprises the following components by mass percentage:

[0011] Octadecylamine 1.0–6.0%;

[0012] Dodecylamine 0.2–2.5%;

[0013] Hexadecylamine 0.1–3.0%;

[0014] N-Oleyl-1,3-Propylene Diamine 0.5–3.0%;

[0015] Surfactant 0.005–0.02%;

[0016] Water balance.

[0017] Preferably, the surfactant is sodium dodecylbenzenesulfonate and / or Tween 80.

[0018] The water used is deionized water.

[0019] A second aspect of the present invention provides a method for preparing a compound corrosion inhibitor for boiler shutdown protection in power plants as described in the first aspect of the present invention, comprising the following steps:

[0020] S1, add the surfactant to the water and mix thoroughly, then add octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine in sequence to form a mixed solution;

[0021] S2, The mixed solution is heated and stirred thoroughly to form a uniform emulsion;

[0022] S3, the emulsion formed in step S2 is cooled to obtain a compound corrosion inhibitor.

[0023] Preferably, step S1 is performed at room temperature.

[0024] Preferably, in step S2, the mixed solution is heated to 60-70°C during the heating process.

[0025] Preferably, in step S2, the stirring time during the stirring process is 0.5 to 2 hours.

[0026] A third aspect of the present invention provides the application of a compound corrosion inhibitor for the protection of power plant boilers during shutdown as described in the first aspect of the present invention, wherein the compound corrosion inhibitor forms a protective film on the surface of the power plant boiler when the power plant boiler is shut down.

[0027] Preferably, the concentration of the compound corrosion inhibitor is 5–30 mg / L.

[0028] The compound corrosion inhibitor for boiler shutdown protection in power plants, its preparation method, and its application provided by this invention have the following beneficial effects:

[0029] 1. Improved liquid phase film formation effect; traditional octadecylamine shutdown protection agent has poor film formation effect in the liquid phase and only has a good film formation effect in the vapor phase; the compound corrosion inhibitor of the present invention also has a good film formation effect in the liquid phase, and further improves the film formation performance in the vapor phase.

[0030] 2. Improved low-temperature film formation effect; the optimal film formation temperature of traditional octadecylamine shutdown protection agent is about 220℃, and the film formation effect is poor below 200℃; the compound corrosion inhibitor of the present invention has good film formation and corrosion inhibition performance in the range of 40℃~400℃. Detailed Implementation

[0031] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with embodiments.

[0032] The present invention provides a compound corrosion inhibitor for the protection of power plant boilers during shutdown, comprising a solvent and a corrosion inhibitor body; the solvent is water; the corrosion inhibitor body comprises octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine and a surfactant.

[0033] In compound corrosion inhibitors, the mass percentage concentration of the main corrosion inhibitor component is 8–12 wt%.

[0034] In a specific embodiment, the compound corrosion inhibitor comprises the following components by mass percentage:

[0035] Octadecylamine 1.0–6.0%;

[0036] Dodecylamine 0.2–2.5%;

[0037] Hexadecylamine 0.1–3.0%;

[0038] N-Oleyl-1,3-Propylene Diamine 0.5–3.0%;

[0039] Surfactant 0.005–0.02%;

[0040] Water balance.

[0041] In the above-mentioned compound corrosion inhibitor, the surfactant is one or two of sodium dodecylbenzene sulfonate and polyoxyethylene sorbitan monooleate (also known as Tween 80); the water is deionized water.

[0042] The compound corrosion inhibitor of the present invention for boiler shutdown protection in power plants, based on the traditional octadecylamine shutdown protection agent, adds dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine to improve the liquid phase film-forming performance, and adds surfactants to improve the low-temperature film-forming performance. Through the emulsification and dispersion effect of the surfactants, the organic amines (octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine) are uniformly distributed in the gas and liquid phases. In particular, it can inhibit the agglomeration of organic amines in the liquid phase, so that the compound corrosion inhibitor can form a uniform protective film on the metal surface of the entire water-steam system.

[0043] The preparation method of the above-mentioned compound corrosion inhibitor for boiler shutdown protection in power plants includes the following steps:

[0044] S1, add the surfactant to the water and mix thoroughly, then add octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine in sequence to form a mixed solution;

[0045] Specifically, the components of the compound corrosion inhibitor are first prepared in proportion. Then, at room temperature, a surfactant is added to deionized water and mixed thoroughly. Next, octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine are added in sequence to form a mixed solution.

[0046] S2, The mixed solution is heated and stirred thoroughly to form a homogeneous emulsion;

[0047] Specifically, the mixed solution obtained in step S1 is heated to 60-70°C and stirred thoroughly for 0.5-2 hours to form a uniform emulsion. The stirring rate during the stirring process is 20 r / min-90 r / min. In a further preferred embodiment, the stirring rate is 40 r / min-80 r / min.

[0048] S3, the emulsion formed in step S2 is cooled to obtain a compound corrosion inhibitor.

[0049] Specifically, the emulsion formed in step S2 is cooled to obtain a compound corrosion inhibitor, which is then packaged for later use.

[0050] When applied, the modified compound corrosion inhibitor prepared in the above process forms a uniform protective film on the metal surface of the entire water-steam system through the combined action of its different components. Specifically, when a power plant boiler is shut down, the compound corrosion inhibitor forms a protective film on the boiler surface, which can be used to inhibit corrosion of the boiler during shutdown. The concentration of the compound corrosion inhibitor is 5–30 mg / L, and it exhibits good film-forming performance within a temperature range of 40℃–400℃.

[0051] The following section provides a further description of the compound corrosion inhibitor and its preparation method for protecting power plant boilers during shutdown, using specific examples.

[0052] Example 1

[0053] The compound corrosion inhibitor used for boiler shutdown protection in this embodiment includes deionized water and a main component of the corrosion inhibitor. The main component comprises octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine, and a surfactant, wherein the surfactant is sodium dodecylbenzenesulfonate. The components of the compound corrosion inhibitor, by mass percentage, are: octadecylamine 5.0%, dodecylamine 1.5%, hexadecylamine 1.0%, N-oleo-1,3-propanediamine 1.0%, surfactant 0.008%, and the balance being deionized water. The mass percentage concentration of the main component in this compound corrosion inhibitor is 8.508%.

[0054] The preparation method of the above corrosion inhibitor includes the following steps:

[0055] (1) At room temperature, add sodium dodecylbenzenesulfonate, a surfactant, to deionized water and mix thoroughly. Then add octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine in sequence to form a mixed solution.

[0056] (2) Heat the mixed solution to 65°C and stir thoroughly for 1 hour at a stirring rate of 40 r / min to form a uniform emulsion.

[0057] (3) After the emulsion is cooled, the compound corrosion inhibitor of this embodiment is obtained and packaged for later use.

[0058] The compound corrosion inhibitor prepared in this embodiment was used to conduct a film formation experiment in an autoclave at a concentration of 25 mg / L. The reaction resistance of the carbon steel specimen after film formation was tested by electrochemical impedance spectroscopy, and the impedance modulus |Z| at 0.01 Hz was used as the reference value. 0.01 | is used to represent the film-forming effect, |Z 0.01 A higher |Z value indicates a better film formation effect. For carbon steel electrodes without a film formation on their surface, the |Z value in water... 0.01 The value is 1.54 kΩ·cm 2 In the compound corrosion inhibitor prepared in this embodiment, after film formation at 100℃, 200℃ and 300℃ respectively, |Z 0.01 The values ​​increased to 530 kΩ·cm. 2 2620 kΩ·cm 2 and 1838 kΩ·cm 2 The corrosion resistance of carbon steel electrodes is significantly improved.

[0059] Example 2

[0060] The compound corrosion inhibitor used for boiler shutdown protection in this embodiment includes deionized water and a main component of the corrosion inhibitor. The main component comprises octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine, and a surfactant, wherein the surfactant is Tween 80. The components of the compound corrosion inhibitor, by mass percentage, are: octadecylamine 3.0%, dodecylamine 2.5%, hexadecylamine 2.0%, N-oleo-1,3-propanediamine 2.0%, surfactant 0.01%, and the balance being deionized water. The mass percentage concentration of the main component in this compound corrosion inhibitor is 9.51%.

[0061] The preparation method of the above corrosion inhibitor includes the following steps:

[0062] (1) At room temperature, add the surfactant Tween 80 to deionized water, mix thoroughly, and then add octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine in sequence to form a mixed solution.

[0063] (2) Heat the mixed solution to 70°C and stir thoroughly for 0.5 h at a stirring rate of 60 r / min to form a uniform emulsion.

[0064] (3) After the emulsion is cooled, the compound corrosion inhibitor of this embodiment is obtained and packaged for later use.

[0065] The compound corrosion inhibitor prepared in this embodiment was used to conduct a film formation experiment in an autoclave at a concentration of 15 mg / L. The reaction resistance of the carbon steel specimen after film formation was tested by electrochemical impedance spectroscopy, and the impedance modulus |Z| at 0.01 Hz was used as the reference value.0.01 | is used to represent the film-forming effect, |Z 0.01 A higher |Z value indicates a better film formation effect. For carbon steel electrodes without a film formation on their surface, the |Z value in water... 0.01 The value is 1.54 kΩ·cm 2 In the compound corrosion inhibitor prepared in this embodiment, after film formation at 50℃, 150℃, 250℃ and 350℃ respectively, |Z 0.01 The values ​​increased to 337 kΩ·cm. 2 980 kΩ·cm 2 2246 kΩ·cm 2 and 1834 kΩ·cm 2 The corrosion resistance of carbon steel electrodes is significantly improved.

[0066] Example 3

[0067] The compound corrosion inhibitor used for boiler shutdown protection in this embodiment includes deionized water and a main component of the corrosion inhibitor. The main component comprises octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine, and a surfactant, wherein the surfactant is Tween 80. The components of the compound corrosion inhibitor, by mass percentage, are: 6.0% octadecylamine, 1.0% dodecylamine, 0.5% hexadecylamine, 1.5% N-oleo-1,3-propanediamine, 0.015% surfactant, and the balance being deionized water. The mass percentage concentration of the main component in this compound corrosion inhibitor is 9.015%.

[0068] The preparation method of the above corrosion inhibitor includes the following steps:

[0069] (1) At room temperature, add the surfactant Tween 80 to deionized water, mix thoroughly, and then add octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine in sequence to form a mixed solution.

[0070] (2) Heat the mixed solution to 60°C and stir thoroughly for 1.5 h at a stirring rate of 80 r / min to form a uniform emulsion.

[0071] (3) After the emulsion is cooled, the compound corrosion inhibitor of this embodiment is obtained and packaged for later use.

[0072] The compound corrosion inhibitor prepared in this embodiment was used to conduct a film formation experiment in an autoclave at a concentration of 8 mg / L. The reaction resistance of the carbon steel specimen after film formation was tested by electrochemical impedance spectroscopy, and the impedance modulus |Z| at 0.01 Hz was used as the reference value. 0.01 | is used to represent the film-forming effect, |Z 0.01 A higher |Z value indicates a better film formation effect. For carbon steel electrodes without a film formation on their surface, the |Z value in water... 0.01 The value is 1.54 kΩ·cm2 In the compound corrosion inhibitor prepared in this embodiment, after film formation at 80℃, 200℃, 300℃ and 400℃ respectively, |Z 0.01 The values ​​increased to 372 kΩ·cm. 2 2090kΩ·cm 2 1850 kΩ·cm 2 and 783 kΩ·cm 2 The corrosion resistance of carbon steel electrodes is significantly improved.

[0073] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A compound corrosion inhibitor for boiler shutdown protection in power plants, characterized in that, The product comprises a solvent and a corrosion inhibitor; the solvent is water; the corrosion inhibitor comprises octadecylamine, dodecylamine, hexadecylamine, N-oleo-1,3-propanediamine, and a surfactant. In the compound corrosion inhibitor, the mass percentage concentration of the corrosion inhibitor bulk is 8-12 wt%. The compound corrosion inhibitor comprises the following components by mass percentage: Octadecylamine 1.0–6.0%; Dodecylamine 0.2–2.5%; Hexadecylamine 0.1–3.0%; N-Oleyl-1,3-Propylene Diamine 0.5–3.0%; Surfactant 0.005–0.02%; Water balance.

2. The compound corrosion inhibitor for boiler shutdown protection in power plants according to claim 1, characterized in that, The surfactant is one or two of sodium dodecylbenzene sulfonate and polyoxyethylene sorbitan monooleate. The water used is deionized water.

3. A method for preparing a compound corrosion inhibitor for boiler shutdown protection in power plants as described in any one of claims 1 to 2, characterized in that, Includes the following steps: S1, add the surfactant to the water and mix thoroughly, then add octadecylamine, dodecylamine, hexadecylamine and N-oleo-1,3-propanediamine in sequence to form a mixed solution; S2, The mixed solution is heated and stirred thoroughly to form a uniform emulsion; S3, the emulsion formed in step S2 is cooled to obtain a compound corrosion inhibitor.

4. The preparation method according to claim 3, characterized in that, Step S1 is performed at room temperature.

5. The preparation method according to claim 3, characterized in that, In step S2, during the heating process, the mixed solution is heated to 60-70°C.

6. The preparation method according to claim 3, characterized in that, In step S2, the stirring time during the stirring process is 0.5 to 2 hours, and the stirring rate is 20 r / min to 90 r / min.

7. The application of a compound corrosion inhibitor for boiler shutdown protection in power plants as described in any one of claims 1 to 2, characterized in that, When the power plant boiler is shut down, the compound corrosion inhibitor forms a protective film on the surface of the power plant boiler.

8. The application according to claim 7, characterized in that, The concentration of the compound corrosion inhibitor is 5–30 mg / L.