Deoxidant for auxiliary deoxidization of boiler feed water as well as preparation method and application of deoxidant

Abstract

The invention relates to the field of deoxidizers, in particular to a deoxidizer for auxiliary deoxidization of boiler feed water as well as a preparation method and application of the deoxidizer. The deoxidant is prepared from the following components: 0.3 percent to 0.5 percent of sodium sulfite, 0.1 percent to 0.3 percent of benzotriazole, 0.1 percent to 0.2 percent of vitamin C, 0.05 percent to 0.1 percent of polyethylene glycol, 0.1 percent to 0.2 percent of acetoxime, 0.1 percent to 0.2 percent of malic acid and the balance of de-softened water. The deoxidant disclosed by the invention shows an excellent deoxidizing effect in a boiler feed water treatment process, has good corrosion inhibition performance, and can effectively keep a system clean and prolong the service life of equipment.

Description

Technical Field

[0001] The invention relates to the field of deoxidizers, and in particular to a deoxidizer used for auxiliary deoxidation of boiler feed water, and a preparation method and application thereof. Background Art

[0002] Dissolved oxygen (DO) in a boiler system refers to the amount of oxygen dissolved in water, which can react with metal parts in the boiler to form oxides, which in turn aggravates corrosion and seriously affects the efficiency and life of the boiler. Studies have shown that for every 1 mg / L increase in dissolved oxygen concentration in a boiler system, the corrosion rate can increase by about 0.2-0.5 mm / year, which will lead to a significant increase in equipment maintenance costs. Therefore, controlling and removing dissolved oxygen in boiler water is crucial to ensuring system stability and reducing long-term operating costs.

[0003] At present, boiler water deoxygenation technologies mainly include physical and chemical methods. Although physical methods such as gas replacement can reduce dissolved oxygen in water to a certain extent, they are often limited by equipment complexity and energy consumption in practical applications. In contrast, chemical deoxygenators directly remove dissolved oxygen through reduction reactions, which are easy to operate and have significant effects. They usually have higher efficiency and economy and are widely used.

[0004] However, traditional chemical deoxidizers have some shortcomings. First, these deoxidizers may produce by-products during use, which may not only cause secondary pollution to the system, but also affect the quality of boiler water. For example, some deoxidizers will produce acidic by-products after the reaction, and additional treatment steps are required to neutralize these by-products. Secondly, the deoxygenation efficiency and stability of traditional deoxidizers may be affected by environmental conditions (such as temperature), resulting in unstable effects in practical applications. Therefore, the development of new deoxidizers with higher efficiency, more stable performance and lower maintenance requirements has become an important direction for improving the performance of boiler systems. Summary of the invention

[0005] To solve the above problems, the present invention provides a deoxygenator for auxiliary deoxygenation of boiler feed water and a preparation method thereof, which can effectively remove dissolved oxygen in boiler feed water and has good corrosion inhibition effect and dispersion performance, thereby ensuring the long-term operation and corrosion resistance of the boiler system.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A deoxidizer for auxiliary deoxidation of boiler feed water is prepared from the following components by mass percentage:

[0008] 0.3%-0.5% sodium sulfite (Na2SO3), 0.1%-0.3% benzotriazole (BTA), 0.1%-0.2% vitamin C (ascorbic acid, C6H8O6), 0.05%-0.1% polyethylene glycol (PEG), 0.1%-0.2% acetone oxime (C3H7NO), 0.1%-0.2% malic acid and the balance softened water.

[0009] In the present invention, the deoxygenation main agent is sodium sulfite, and the deoxygenation auxiliary agent is a combination of benzotriazole (BTA), vitamin C (ascorbic acid, C6H8O6), acetone oxime (C3H7NO) and malic acid. The deoxygenation auxiliary agent plays a catalytic deoxygenation role, which can accelerate the reaction rate of the deoxygenation main agent sodium sulfite and dissolved oxygen, thereby effectively improving the removal rate of low-concentration dissolved oxygen, and reducing the dosage of the deoxygenation main agent. Among them, benzotriazole (BTA) is used as a corrosion inhibitor, and its aromatic ring π electrons overlap with the 3d empty orbits of the metal Fe atom to form a π-d bond, enhance its adsorption capacity on the metal surface, strengthen chemical adsorption, and significantly enhance corrosion inhibition. In addition, the protective film formed by BTA on the metal surface can effectively prevent metal corrosion. Vitamin C (ascorbic acid, C6H8O6) is a strong antioxidant, and the phenolic hydroxyl group in its molecule is easy to react with dissolved oxygen to generate quinone compounds, and then the quinone substances continue to react with dissolved oxygen to generate carboxylic acid substances. On the other hand, quinones can also be reduced to polyhydroxyphenols by the deoxidizer main agent or its decomposition products such as hydrazine, carbohydrazide, etc., and polyhydroxyphenols continue to react with dissolved oxygen to generate quinones again, so that the cycle improves the deoxidation efficiency. Acetone oxime (C3H7NO) has good reducibility and chelating ability, and can react with dissolved oxygen to generate carboxylic acid substances. At the same time, acetone oxime can chelate metal ions in water, reduce the generation of corrosion products, and avoid metal salts from being deposited in pipelines or boilers. Malic acid is used as a pH regulator, and the carboxyl group in its molecule can chelate with metal ions to generate complexes to avoid metal salts from being deposited in pipelines or boilers. In addition, malic acid can react with dissolved oxygen at high temperatures to generate carboxylic acid substances, and the synergistic deoxidation effect with the nitrogen-containing functional groups in the deoxidation main agent is significant. The deoxidation auxiliary agent in the deoxidizer of the present invention has a good synergistic effect with the deoxidation main agent, can effectively reduce the dosage of the deoxidation main agent, and accelerate the reaction rate of the deoxidation main agent with dissolved oxygen, thereby improving the removal rate of dissolved oxygen. Deoxidation agents are all reducing substances, which can effectively stabilize the redox potential of the system and improve the efficiency of the main deoxidation agent. At the same time, deoxidation agents have a corrosion inhibition effect and can form a protective film on the surface of carbon steel to prevent corrosion of carbon steel. This is because the lone pair of electron atoms in the deoxidation agent molecules can share free electron pairs with metal atoms or transfer charges, thereby forming a strong chemical bond and forming a chemical adsorption layer on the metal surface, blocking the contact between dissolved oxygen and metal.

[0010] Specific:

[0011] Sodium sulfite (Na2SO3) is the main deoxygenating agent. Through reduction reaction, it can quickly consume dissolved oxygen in water and generate harmless sulfate, thereby effectively removing low-concentration dissolved oxygen and achieving efficient deoxygenation effect. The reaction is as follows:

[0012] 2Na2SO3+O2→2Na2SO4

[0013] Benzotriazole (BTA) is a corrosion inhibitor. It can form a stable coordination bond by combining with the active sites on the metal surface, and then form a protective film on the metal surface, effectively preventing the occurrence of metal corrosion reactions. The reaction is as follows:

[0014] BTA+Fe→Fe-BTA

[0015] Vitamin C (ascorbic acid, C6H8O6) is a strong antioxidant. As an organic catalyst, it reacts with dissolved oxygen through its reducing action to generate harmless byproducts, which can further enhance the deoxygenation effect of the deoxygenator, thereby improving the overall deoxygenation efficiency. The reaction is as follows:

[0016] (3) C6H8O6+O2→C6H6O6+H2O

[0017] As a dispersant, polyethylene glycol (PEG) helps other active components to dissolve and disperse better in water through its hydrophilic molecular structure. It can significantly improve the solubility and dispersibility of the deoxygenator in water, ensure the uniform distribution of each component in water, and thus improve the deoxygenation effect.

[0018] Acetone oxime (C3H7NO) has good reducing and chelating abilities and can react with dissolved oxygen. At the same time, acetone oxime can combine with metal ions in water to form chelates, reducing the generation of corrosion products. The reaction is as follows:

[0019] C3H7NO+O2→C3H7NO2

[0020] As an organic acid, malic acid is mainly used in the present invention to adjust the pH value of the deoxidizer solution to maintain it within a suitable range, thereby optimizing the efficiency of the deoxidation reaction. The carboxyl group in the malic acid molecule can effectively neutralize the alkaline substances in the water, maintain the acidic environment of the solution, and ensure the optimal reaction activity of the deoxidizer main agent and auxiliary agent. In addition, malic acid has a good chelating effect and can react with metal ions (such as Fe 2+ , Cu 2+) forms a stable complex, reduces the formation of metal oxides and precipitates, and avoids the deposition of metal salts in pipes or boilers. Malic acid can react with dissolved oxygen at high temperatures to generate carboxylic acid substances, and has a significant synergistic deoxygenation effect with the nitrogen-containing functional groups in the deoxygenating agent. Specifically, malic acid reacts with dissolved oxygen at high temperatures to generate carboxylic acid substances such as 2-hydroxysuccinic acid. These reaction products further adsorb on the metal surface to form a protective layer, enhancing the anti-corrosion effect. By adjusting the pH value of the solution and the chelation effect, malic acid not only improves the overall deoxygenation efficiency of the deoxygenator, but also significantly reduces the corrosion risk of metal pipes and boiler inner walls. The reaction is as follows:

[0021] HOOC-CH2CH(OH)-COOH+Fe 2+ →Fe

[0022] Preferably, the deoxidizer for auxiliary deoxidation of boiler feed water of the present invention is prepared from the following components by mass percentage:

[0023] 0.4% sodium sulfite (Na2SO3), 0.2% benzotriazole (BTA), 0.1% vitamin C (ascorbic acid, C6H8O6), 0.05% polyethylene glycol (PEG), 0.2% acetone oxime (C3H7NO) and 0.2% malic acid, the balance being demineralized water.

[0024] Preferably, the deoxidizer for auxiliary deoxidation of boiler feed water of the present invention is prepared from the following components by mass percentage:

[0025] 0.5% sodium sulfite (Na2SO3), 0.3% benzotriazole (BTA), 0.15% vitamin C (ascorbic acid, C6H8O6), 0.07% polyethylene glycol (PEG), 0.25% acetone oxime (C3H7NO) and 0.25% malic acid, the balance being demineralized water.

[0026] The present invention also provides a method for preparing the above-mentioned deoxidizer for auxiliary deoxidation of boiler feed water, comprising the following steps:

[0027] Sodium sulfite, benzotriazole, vitamin C, polyethylene glycol, acetone oxime and malic acid are dissolved in appropriate amount of softened water according to the proportion, and the mixture is stirred thoroughly to ensure that all the ingredients are completely dissolved and evenly distributed, and then filtered to remove the insoluble matter to obtain the deoxidizer solution. Specifically, the method includes the following steps: add an appropriate amount of softened water to the reaction vessel and heat it to 30-50°C, slowly add 0.4%-0.5% of sodium sulfite (Na2SO3), stir for 10-20 minutes at a stirring speed of 200-300rpm until it is completely dissolved; then, add 0.2%-0.3% of benzotriazole (BTA), and maintain the stirring speed at 100-200rpm, and continue stirring for 15-25 minutes; add 0.1%-0.15% of vitamin C (ascorbic acid, C6H8O6), and adjust the temperature of the solution during this period. to 25-35° C., and stir for 5-15 min; then add 0.05%-0.1% polyethylene glycol (PEG), keep the stirring speed at 50-100 rpm, and extend the stirring time to 20-30 min; add 0.2%-0.3% acetone oxime (C3H7NO3) and 0.2%-0.25% malic acid in sequence, keep the solution temperature at 20-30° C., and stir for 10-20 min; finally, cool the solution to room temperature, add softened water to a total of 20 mL, and mix thoroughly until all components are completely dissolved and evenly distributed, and filter to obtain the product.

[0028] The deoxidizer of the present invention can be used to assist thermal deoxidation of boilers. The specific process of application is: after purified water passes through a thermal deoxidizer, the dissolved oxygen in the water body is reduced to 10 mg / L or below, and then the deoxidizer is added to the deoxidation water tank or the boiler feed water pipeline, and the dosage is generally 45:1500. It is found that after the deoxidation reaction of the deoxidizer of the present invention, the dissolved oxygen in the boiler water is reduced to below 3 mg / L.

[0029] The present invention has the following beneficial effects:

[0030] Through the synergistic effect of multiple ingredients such as sodium sulfite, benzotriazole, vitamin C, acetone oxime and malic acid, dissolved oxygen can be efficiently removed and deoxygenation efficiency can be significantly improved. As the main reducing agent, sodium sulfite can react quickly with dissolved oxygen, and adjuvants such as benzotriazole, vitamin C and acetone oxime further accelerate this reaction process and provide additional antioxidant and corrosion protection. Secondly, malic acid, as a pH regulator, ensures that the deoxidizer operates under the optimal acid-base environment, while reducing the generation of metal oxides and precipitates through chelation, avoiding the deposition of metal salts in pipelines and boilers. On the whole, the deoxidizer of the present invention not only improves the deoxidation effect, but also effectively reduces the use of the deoxidation main agent, improves the stability and economy of the system, and extends the service life of boiler equipment. It has the characteristics of high efficiency, stability and environmental protection, and is suitable for various industrial boiler systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0032] Figure 1 It is a deoxidizer test device used in the embodiments of the present invention;

[0033] In the figure: 1-probe; 2-oil bath; 3-heating table. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0035] Preparation of main ingredients:

[0036] Sodium sulfite (Na2SO3): Take appropriate amounts of high-purity sulfur dioxide gas and sodium hydroxide solution. Pass an appropriate amount (about 50L / h) of sulfur dioxide gas into 500L of sodium hydroxide solution (concentration is 20%) to react and generate sodium sulfite. Remove insoluble matter by filtration, evaporate and concentrate the resulting solution, and crystallize to obtain pure sodium sulfite.

[0037] Benzotriazole (BTA): Prepare 100g of o-phenylenediamine and 150g of sodium nitrite solution (10%). Under acidic conditions, o-phenylenediamine and sodium nitrite are mixed to react to generate diazide, which is further cyclized to generate benzotriazole.

[0038] Acetone oxime (C3H7NO): Prepare 200 mL of acetone and 150 mL of hydroxylamine solution (10%). Under acidic conditions, acetone and hydroxylamine undergo a condensation reaction to generate acetone oxime.

[0039] Malic acid: Prepare 500g of maleic acid and 200mL of water. Maleic acid is hydrogenated to produce malic acid in the presence of a nickel catalyst.

[0040] Example 1

[0041] The deoxidizer of the present invention is prepared from the following components in mass percentage: 0.4% sodium sulfite (Na2SO3), 0.2% benzotriazole (BTA), 0.1% vitamin C (ascorbic acid, C6H8O6), 0.05% polyethylene glycol (PEG), 0.2% acetone oxime (C3H7NO) and 0.2% malic acid, and the balance is softened water. Among them, the deoxidizer main agent is composed of sodium sulfite (Na2SO3); the deoxidizer auxiliary agent is composed of benzotriazole (BTA), vitamin C (ascorbic acid, C6H8O6) and acetone oxime (C3H7NO), and the mixing mass ratio is 1:0.5:1; the dispersant is polyethylene glycol (PEG); and the pH regulator is malic acid. The above-mentioned deoxidizer is prepared by the following method: first, an electronic balance is used to accurately weigh the following according to the formula: 0.4g sodium sulfite, 0.2g benzotriazole, 0.1g vitamin C, 0.05g polyethylene glycol, 0.2g acetone oxime and 0.2g malic acid. Then, each component is added to a double-necked flask in the order of sodium sulfite, benzotriazole, vitamin C, polyethylene glycol, acetone oxime and malic acid, and dissolved in an appropriate amount of softened water to make the total solution volume reach 100 ml; then, the double-necked flask is placed in a constant temperature oil bath pot, the temperature is set to 85°C, and a magnetic stirrer is used to stir and mix thoroughly to ensure that all components are completely dissolved and evenly distributed. Finally, the mixed solution is filtered to remove insoluble matter to obtain a final deoxidizer solution for standby use.

[0042] Take 45 μL of the obtained deoxygenator solution and add it to 15 ml of the water sample to be treated, and measure the change in dissolved oxygen before and after the addition.

[0043] Example 2

[0044] The deoxidizer of the present invention is prepared from the following components in mass percentage: 0.5% sodium sulfite (Na2SO3), 0.3% benzotriazole (BTA), 0.15% vitamin C (ascorbic acid, C6H8O6), 0.07% polyethylene glycol (PEG), 0.25% acetone oxime (C3H7NO) and 0.25% malic acid, and the balance is softened water. Among them, the deoxidizer main agent is composed of sodium sulfite (Na2SO3); the deoxidizer auxiliary agent is composed of benzotriazole (BTA), vitamin C (ascorbic acid, C6H8O6) and acetone oxime (C3H7NO), and the mixing mass ratio thereof is 1:0.5:0.8; the dispersant is polyethylene glycol (PEG); and the pH regulator is malic acid. The above deoxidizer is prepared by the following method: first, an electronic balance is used to accurately weigh the following according to the formula: 0.5g sodium sulfite, 0.3g benzotriazole, 0.15g vitamin C, 0.07g polyethylene glycol, 0.25g acetone oxime and 0.25g malic acid. Then, each component is added to a two-necked flask in the order of sodium sulfite, benzotriazole, vitamin C, polyethylene glycol, acetone oxime and malic acid, and dissolved in an appropriate amount of softened water to make the total solution volume reach 100 ml; then, the two-necked flask is placed in a constant temperature oil bath pot, the temperature is set to 85°C, and a magnetic stirrer is used to stir and mix thoroughly to ensure that all components are completely dissolved and evenly distributed. Finally, the mixed solution is filtered to remove insoluble matter to obtain a final deoxidizer solution for standby use.

[0045] Take 45 μL of the obtained deoxygenator solution and add it to 15 ml of the water sample to be treated, and measure the change in dissolved oxygen before and after the addition.

[0046] Performance Test:

[0047] Take commercial deoxygenator (HD-008A from Qinglingling Energy Saving Technology Co., Ltd.) as comparative example 1, take 45 μL of commercial deoxygenator (HD-008A from Qinglingling Energy Saving Technology Co., Ltd.) solution, add it to 15 ml of the water sample to be treated, and measure the change in dissolved oxygen content before and after adding.

[0048] Experimental method: Add deoxidizer to the water sample to be treated in proportion, use the Leiji portable micro dissolved oxygen analyzer (JPB-607A) to monitor the dissolved oxygen concentration in the solution in real time, and record the initial dissolved oxygen concentration and the changes in dissolved oxygen concentration at different time points. During the experiment, keep a constant temperature and take samples at regular intervals, and evaluate the deoxidation effect of the deoxidizer by analyzing the changes in dissolved oxygen concentration.

[0049] Table 1 shows the deoxygenation effects of the deoxygenators in Example 1, Example 2 and Comparative Example 1

[0050]

[0051] The experimental results show that the dissolved oxygen concentrations of Example 1, Example 2 and Comparative Example 1 change at different time points as follows: at 0 minutes, the dissolved oxygen concentration of Example 1 is 5.06 mg / L, that of Example 2 is 5.10 mg / L, and that of Comparative Example 1 is 5.08 mg / L. At 1 minute, the dissolved oxygen concentrations of Example 1, Example 2 and Comparative Example 1 drop to 3.85 mg / L, 3.70 mg / L and 4.25 mg / L, respectively. At 5 minutes (stable reading), the dissolved oxygen concentration of Example 1 drops further to 2.62 mg / L, that of Example 2 is 2.54 mg / L, and that of Comparative Example 1 is 2.95 mg / L.

[0052] It can be seen that the deoxidizers used in Examples 1 and 2 significantly reduced the concentration of dissolved oxygen in a relatively short period of time, and the reduction was significantly better than that in Comparative Example 1. Specifically, Example 2 had the best dissolved oxygen removal effect at 1 minute and 5 minutes, indicating that the formula performed well in improving deoxidation efficiency. In addition, although Comparative Example 1 also showed a certain deoxidation effect, its deoxidation efficiency was significantly lower than that of Examples 1 and 2.

[0053] By comprehensively comparing the experimental data of the embodiments and the comparative examples, the following conclusions can be drawn: the deoxidizer formulations of Examples 1 and 2 have high deoxidation efficiency, can rapidly reduce the dissolved oxygen concentration in a short period of time, and the final stable value is significantly lower than that of Comparative Example 1. This shows that the multi-component synergistic deoxidation formulation proposed in the present invention has significant advantages in improving the deoxidation effect and efficiency, can more effectively prevent oxidation corrosion of metal parts in the boiler system, extend the service life of the equipment, and improve the operational reliability and economy of the industrial boiler system.

[0054] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A deoxidizer for auxiliary deoxidation of boiler feed water, characterized in that: The composition is prepared from the following components by mass percentage: 0.3%-0.5% sodium sulfite, 0.1%-0.3% benzotriazole, 0.1%-0.2% vitamin C, 0.05%-0.1% polyethylene glycol, 0.1%-0.2% acetone oxime, 0.1%-0.2% malic acid and the balance demineralized water.

2. The deoxidizer for auxiliary deoxidation of boiler feed water according to claim 1, characterized in that: The main deoxidizing agent is sodium sulfite, and the auxiliary deoxidizing agent is a combination of benzotriazole, vitamin C, acetone oxime and malic acid.

3. The deoxidizer for auxiliary deoxidation of boiler feed water according to claim 1, characterized in that: The composition is prepared from the following components by mass percentage: 0.4% sodium sulfite, 0.2% benzotriazole, 0.1% vitamin C, 0.05% polyethylene glycol, 0.2% acetone oxime and 0.2% malic acid, and the balance is demineralized water.

4. The deoxidizer for auxiliary deoxidation of boiler feed water according to claim 1, characterized in that: The composition is prepared from the following components by mass percentage: 0.5% sodium sulfite, 0.3% benzotriazole, 0.15% vitamin C, 0.07% polyethylene glycol, 0.25% acetone oxime and 0.25% malic acid, and the balance is demineralized water.

5. A method for preparing a deoxidizer for auxiliary deoxidation of boiler feed water according to any one of claims 1 to 4, characterized in that: The following steps are involved: Sodium sulfite, benzotriazole, vitamin C, polyethylene glycol, acetone oxime and malic acid are dissolved in appropriate amount of softened water according to the proportion, stirred and mixed sufficiently to ensure that all the ingredients are completely dissolved and evenly distributed, and then filtered to remove insoluble matter to obtain a deoxidizer solution.

6. The preparation method according to claim 5, characterized in that: The order of adding the components is sodium sulfite, benzotriazole, vitamin C, polyethylene glycol, acetone oxime and malic acid to ensure that the components are fully mixed and dissolved.

7. The preparation method according to claim 5, characterized in that: The specific steps include: Add an appropriate amount of softened water to the reaction vessel and heat it to 30-50°C, slowly add 0.4%-0.5% sodium sulfite, stir at a stirring speed of 200-300rpm for 10-20min until it is completely dissolved; then, add 0.2%-0.3% benzotriazole, maintain the stirring speed at 100-200rpm, and continue stirring for 15-25min; add 0.1%-0.15% vitamin C, and during this period adjust the temperature of the solution to 25-35°C, stir for 5- 15min; then add 0.05%-0.1% polyethylene glycol, keep the stirring speed at 50-100rpm, and extend the stirring time to 20-30min; add 0.2%-0.3% acetone oxime and 0.2%-0.25% malic acid in sequence, keep the solution temperature at 20-30℃, and stir for 10-20min; finally, let the solution stand and cool to room temperature, add softened water to a total of 20mL, and mix thoroughly until all components are completely dissolved and evenly distributed, and filter to obtain.

8. The use of a deoxidizer for auxiliary deoxidation of boiler feed water according to any one of claims 1 to 4, characterized in that: The deoxidizer can be used to assist thermal deoxidation of boilers.

9. The use according to claim 8, characterized in that: The method comprises the following steps: after the purified water passes through the thermal deaerator, the dissolved oxygen in the water body is reduced to 10 mg / L or below, and then the deoxidizer is added into the deoxidized water tank or the boiler feed water pipeline, and the dosage is 45:1500.

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