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

Abstract

The application relates to a compounded corrosion inhibitor for power plant shutdown protection and a preparation method and application thereof, the compounded corrosion inhibitor comprising a corrosion inhibitor main body, a solubilizing agent and an emulsifier; the corrosion inhibitor main body is octadecylamine, the solubilizing agent is lauryl alcohol polyoxyethylene ether, and the emulsifier is poloxamer; the preparation method comprises the following steps: S1, heating and dissolving octadecylamine into a thick liquid; S2, adding the solubilizing agent into the liquid formed in the step S1 to stir to form a uniform liquid; S3, adding the emulsifier into the liquid formed in the step S2 to stir to form a uniform emulsion; and S4, cooling the emulsion formed in the step S3 to obtain the compounded corrosion inhibitor; when a power plant boiler is stopped, the compounded corrosion inhibitor forms a protective film on the surface of the power plant boiler. Compared with the prior art, the compounded corrosion inhibitor has good corrosion inhibition performance on the boiler steel in a liquid phase region, can form a uniform and dense protective film on the surface of carbon steel, and has good protection effect.

Description

Technical Field

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

[0002] Shutdown corrosion is one of the important issues affecting the safe operation of generator units. Power plant shutdown protection can be divided into two types: dry protection and wet protection. Dry protection includes drying method, desiccant method, film-forming amine method, etc., while wet protection includes ammonia-hydrazine protection method, steam pressure method, feedwater pressure method, etc.

[0003] Octadecylamine has become the most commonly used film-forming corrosion inhibitor for boiler shutdown protection in power plants. It can form a hydrophobic protective film on the surface of boiler steel, preventing direct contact between oxygen and moisture in the environment and the boiler steel, thus providing good protection for the boiler system. Its film-forming effect is less affected by the external environment and has a wide coverage, effectively protecting even complex pipelines. Moreover, it is suitable for boiler shutdown maintenance and has great application potential.

[0004] However, the current octadecylamine shutdown protection has disadvantages such as short protection time, poor liquid phase protection performance, and high requirements for film formation temperature. Under the current situation of frequent shutdowns of thermal power units, there is a need for a shutdown protection agent with better performance to improve the liquid phase film formation performance and to be used for shutdown protection of boilers in power plants with frequent shutdowns. Summary of the Invention

[0005] The purpose of this invention is to provide a compound corrosion inhibitor for power plant shutdown protection, its preparation method and application, which can form a uniform and dense protective film on the surface of carbon steel, and has a good protective effect.

[0006] The objective of this invention can be achieved through the following technical solution: a compound corrosion inhibitor for power plant shutdown protection, comprising a corrosion inhibitor body, a solubilizer, and an emulsifier; wherein the corrosion inhibitor body is octadecylamine, the solubilizer is lauryl alcohol polyoxyethylene ether, and the emulsifier is poloxamer.

[0007] Preferably, in the compound corrosion inhibitor, the mass percentage of the corrosion inhibitor body is 60-90 wt%, the mass percentage of the solubilizer is 5-20 wt%, and the mass percentage of the emulsifier is 5-20 wt%.

[0008] More preferably, in the compound corrosion inhibitor, the mass percentage of the corrosion inhibitor body is 70-85 wt%.

[0009] A method for preparing the above-mentioned compound corrosion inhibitor for power plant shutdown protection includes the following steps:

[0010] S1, Dissolve octadecylamine by heating into a thick liquid;

[0011] S2, add the solubilizer to the liquid formed in step S1 and stir to form a homogeneous liquid;

[0012] S3, add the emulsifier to the liquid formed in step S2 and stir to form a uniform emulsion;

[0013] S4, the emulsion formed in step S3 is cooled to obtain the compound corrosion inhibitor.

[0014] Preferably, the preparation method of the compound corrosion inhibitor for power plant shutdown protection includes the following steps:

[0015] S1, a certain amount of octadecylamine is placed in a beaker and heated in a water bath to dissolve it into a thick liquid;

[0016] S2, a certain amount of solubilizer is slowly added to the liquid formed in step S1, while stirring slowly during the addition process, and the temperature is kept stable until a homogeneous liquid is formed.

[0017] S3, a certain amount of emulsifier is slowly added to the liquid formed in step S2, while stirring slowly during the addition process, and the temperature is kept stable until a uniform emulsion is formed.

[0018] S4, the emulsion formed in step S3 is cooled to obtain a compound corrosion inhibitor.

[0019] Preferably, the heating temperature in step S1 is 60-90°C, and the temperature is maintained to dissolve the octadecylamine solid block into a liquid.

[0020] More preferably, the heating temperature in step S1 is 65-90℃.

[0021] More preferably, the heating temperature in step S1 is 70-90°C.

[0022] Preferably, in step S2, the temperature is kept stable until a homogeneous liquid is formed, the temperature is kept at 60-90°C, and the holding time is 10-40 minutes.

[0023] Preferably, the stirring time in step S2 is 10-40 min, and the stirring rate is 10-50 r / min.

[0024] Preferably, in step S3, the temperature is kept stable until a uniform emulsion is formed, the temperature is kept at 60-90°C, and the holding time is 10-40 minutes.

[0025] Preferably, the stirring time in step S3 is 10-40 min, and the stirring rate is 10-50 r / min.

[0026] An application of the above-mentioned compound corrosion inhibitor for power plant boiler shutdown protection, wherein when the power plant boiler is shut down, the compound corrosion inhibitor forms a protective film on the surface of the power plant boiler.

[0027] Preferably, the concentration of the compound corrosion inhibitor is 10–50 mg / L. When applied, the compound corrosion inhibitor, through the combined action of its different components, can form a uniform protective film on the entire metal surface of the water-steam system. 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 during the shutdown period.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. This invention, based on the traditional octadecylamine shutdown protection agent, adds a solubilizer and an emulsifier. The film-forming corrosion inhibitor formed by these three components 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 the liquid phase region, and can form a uniform and dense protective film on the carbon steel surface, providing excellent protection.

[0030] 2. This invention utilizes the solubilizing effect of the solubilizer and the emulsifying and dispersing effect of the emulsifier to ensure uniform distribution of organic amines in the gas and liquid phases, thereby improving the film-forming effect in the liquid phase. In particular, it can suppress the aggregation of organic amines in the liquid phase, enabling the compounded corrosion inhibitor to form a uniform protective film on the metal surface of the entire water vapor system.

[0031] 3. The liquid-phase film-forming performance of the compound corrosion inhibitor of this invention is significantly improved, resulting in better protective effects. Poloxamer, as a novel high-molecular-weight nonionic surfactant, not only acts as an emulsifier but also has a solubilizing effect. Compared with other common compound corrosion inhibitors, this compound corrosion inhibitor has better film-forming properties and a better inhibitory effect on boiler corrosion. Attached Figure Description

[0032] Figure 1 This is a Nyquist image of the carbon steel electrode in Example 1 of the present invention after a film formation experiment;

[0033] Figure 2 This is a Bode image of the carbon steel electrode in Example 1 of the present invention after a film formation experiment;

[0034] Figure 3 This is an impedance diagram of the carbon steel electrode in Example 1 of the present invention after a film formation experiment, showing the change over time. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0036] Example 1

[0037] The compound corrosion inhibitor used for boiler shutdown protection in this embodiment includes a corrosion inhibitor body, a solubilizer, and an emulsifier; the body is octadecylamine, the solubilizer is lauryl alcohol polyoxyethylene ether, and the emulsifier is poloxamer.

[0038] The preparation method of the above corrosion inhibitor includes the following steps:

[0039] (1) Weigh 50g of octadecylamine solid, put it in a beaker, heat it in a water bath to 80°C, and stir it continuously with a glass rod until the octadecylamine solid dissolves into a thick liquid.

[0040] (2) Weigh 8g of lauryl alcohol polyoxyethylene ether and slowly add it to the viscous liquid in (1). At the same time, stir continuously with a glass rod to accelerate dissolution. After the reaction is complete, continue stirring for 20 minutes at a stirring rate of 40r / min.

[0041] (3) Weigh 10g of poloxamer and slowly add it to the viscous liquid in (2). At the same time, stir continuously with a glass rod to accelerate dissolution. After the reaction is complete, continue stirring for 30 minutes at a stirring rate of 40r / min.

[0042] The compound corrosion inhibitor prepared in this embodiment was added to deionized water to prepare an emulsion with a concentration of 50 mg / L. A film-forming experiment was conducted on carbon steel in an autoclave at a temperature of 220°C. The concentrations of both octadecylamine and the compound corrosion inhibitor were 50 mg / L. The reaction resistance of the carbon steel sample after film formation was tested using electrochemical impedance spectroscopy, with the impedance modulus |Z| at 0.01 Hz being used. 0.01 The value is used to represent the film-forming effect, |Z| 0.01 The higher the value, the better the film-forming effect.

[0043] The Nyquist and Bode plots of the carbon steel electrode after the film formation experiment in this embodiment are as follows: Figures 1-2 As shown, the results indicate that carbon steel electrodes without a film on their surface exhibit |Z| in water. 0.01 The value is 23.5 kΩ·cm 2 The carbon steel electrode with octadecylamine film in water |Z| 0.01 The value is 77.6 kΩ·cm 2 Using the compound corrosion inhibitor prepared in this embodiment, after film formation at 220°C, |Z| 0.01 The value increased to 316.2 kΩ·cm 2 The corrosion resistance of carbon steel electrodes is significantly improved.

[0044] Furthermore, when the compound corrosion inhibitor does not contain poloxamer, the carbon steel electrode in water after film formation exhibits |Z| 0.01 The value is 86.4 kΩ·cm 2 Without lauryl alcohol polyoxyethylene ether, the carbon steel electrode in water after film formation |Z| 0.01 The value is 157.2 kΩ·cm 2 This indicates that the combination of octadecylamine with cinnamyl alcohol polyoxyethylene ether and poloxamer can achieve better film-forming effect.

[0045] The impedance diagram of the carbon steel electrode over time after the film formation experiment in this embodiment is shown below. Figure 3 As shown, the results indicate that the compound corrosion inhibitor prepared in this embodiment has a long protection time and still exhibits good film-forming properties after 6 months.

[0046] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A compound corrosion inhibitor for power plant shutdown protection, characterized in that, It includes a corrosion inhibitor, a solubilizer, and an emulsifier; the corrosion inhibitor is octadecylamine, the solubilizer is lauryl alcohol polyoxyethylene ether, and the emulsifier is poloxamer. In the aforementioned compound corrosion inhibitor, the mass percentage of the corrosion inhibitor body is 60-90 wt%, the mass percentage of the solubilizer is 5-20 wt%, and the mass percentage of the emulsifier is 5-20 wt%. The preparation method of the compound corrosion inhibitor for power plant shutdown protection includes the following steps: S1, Dissolve octadecylamine by heating into a thick liquid; S2, add the solubilizer to the liquid formed in step S1 and stir to form a homogeneous liquid; S3, add the emulsifier to the liquid formed in step S2 and stir to form a uniform emulsion; S4, the emulsion formed in step S3 is cooled to obtain the compound corrosion inhibitor; The stirring time in step S2 is 10~40 min, and the stirring speed is 10~50 r / min; The stirring time in step S3 is 10~40 min, and the stirring speed is 10~50 r / min; When the power plant boiler is shut down, the compound corrosion inhibitor forms a protective film on the surface of the power plant boiler; The concentration of the compound corrosion inhibitor is 10~50 mg / L.

2. The compound corrosion inhibitor for power plant shutdown protection according to claim 1, characterized in that, The heating temperature in step S1 is 60-90℃.

3. The compound corrosion inhibitor for power plant shutdown protection according to claim 1, characterized in that, Step S2: Maintain a stable temperature until a homogeneous liquid is formed. Maintain the temperature at 60-90°C for 10-40 minutes.

4. The compound corrosion inhibitor for power plant shutdown protection according to claim 1, characterized in that, Step S3: Maintain a stable temperature until a homogeneous emulsion is formed. Maintain the temperature at 60-90°C for 10-40 minutes.

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