Preparation method of low-paint-film steam turbine oil

Abstract

The invention discloses a preparation method of low-paint-film steam turbine oil, and belongs to the technical field of turbine oil. Comprising the following raw materials in parts by weight: 88 to 93 parts of base oil, 5 to 10 parts of oil-soluble polyether, 0.3 to 1.0 part of a self-made antioxidant, 0.5 to 1.0 part of a phenolic antioxidant, 0.05 to 0.15 part of an anti-rust agent, 0.02 to 0.1 part of a metal deactivator, 0.1 to 0.2 part of a pour point depressant and 0.005 to 0.01 part of an anti-foaming agent. According to the invention, the self-made antioxidant is compounded with the phenolic antioxidant, so that the oxidation resistance of the oil product is greatly improved, and the generation of polar oxidation products is reduced; due to the highly hydrogenated base oil, the comprehensive performance of an oil product is improved, and the paint film tendency index of the highly hydrogenated base oil is relatively low; oil-soluble polyether is added, so that polar oxidation products generated or being formed in a system can be effectively dissolved, and the tendency index of a paint film is reduced; therefore, the invention has important application value in the technical field of turbine oil.

Description

Technical Field

[0001] This invention belongs to the field of turbine oil technology, specifically, it relates to a method for preparing a low-varnish turbine oil. Background Technology

[0002] As a crucial working medium in the circulating lubrication system of key equipment such as steam turbine generator sets, the long-term stability of turbine oil directly affects the safety and efficiency of the equipment. In existing technologies, turbine oils typically use deeply refined base oils and are compounded with various functional additives (such as antioxidants, rust inhibitors, and antifoaming agents) to meet basic lubrication and protection requirements. However, after long-term operation under complex conditions such as high temperature, high pressure, oxygen, and metal catalysis, the oxidative degradation of the base oil and additives is inevitable, producing a large amount of polar oxidation products such as carboxylic acids, ketones, and aldehydes. These substances have limited solubility in the oil and easily aggregate and deposit on metal surfaces (such as bearings, servo valves, and oil circuit systems), gradually forming a highly adhesive varnish layer.

[0003] Currently, while commonly used antioxidant systems (such as traditional amine or phenolic antioxidants) can delay oil oxidation to some extent, their antioxidant efficiency is limited, especially under high-temperature, long-term operating conditions, making it difficult to completely inhibit the formation of oxidation products. Furthermore, although conventional base oils have good oxidation stability, their ability to dissolve polar oxidation products is limited, failing to effectively prevent the precipitation and deposition of varnish precursors. While some existing research has attempted to introduce dissolving components, such as certain esters or polyethers, these often fail to achieve ideal results in practical applications due to poor compatibility with the oil system or insignificant varnish inhibition effects.

[0004] Therefore, there is an urgent need to develop a high-performance turbine oil that combines excellent antioxidant properties with varnish control capabilities, which can extend the service life of the oil while effectively inhibiting the formation and deposition of varnish, thereby ensuring the long-term stable operation of the turbine unit. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing low-varnish turbine oil.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a low-varnish turbine oil includes the following steps: A1. In the reaction vessel, add the self-made antioxidant, phenolic antioxidant and base oil, turn on the mechanical stir and heat to 70-80℃ to fully dissolve the raw materials and obtain a mixture; A2. Continue to add oil-soluble polyether, rust inhibitor, metal deactivator, pour point depressant and antifoaming agent to the reactor, and stir and mix for 0.5-1.5 hours. Then cool to 40-50°C to obtain low-film turbine oil.

[0007] As a further technical solution, the raw materials are as follows by weight: 88-93 parts base oil, 5-10 parts oil-soluble polyether, 0.3-1.0 parts self-made antioxidant, 0.5-1.0 parts phenolic antioxidant, 0.05-0.15 parts rust inhibitor, 0.02-0.1 parts metal deactivator, 0.1-0.2 parts pour point depressant, and 0.005-0.01 parts antifoaming agent.

[0008] As a further technical solution, the base oil is a highly hydrogenated base oil.

[0009] As a further technical solution, the oil-soluble polyether is an ethylene oxide / propylene oxide block copolymer.

[0010] As a further technical solution, the phenolic antioxidant is a hindered phenolic antioxidant.

[0011] As a further technical solution, the rust inhibitor is one of dodecenyl succinate half ester and dodecenyl succinate.

[0012] As a further technical solution, the metal deactivator is a benzotriazole deactivator.

[0013] As a further technical solution, the pour point depressant is a polymethacrylate-based pour point depressant.

[0014] As a further technical solution, the antifoaming agent is an organosilicon-based antifoaming agent.

[0015] As a further technical solution, the self-made antioxidant is prepared through the following steps: B1. Feeding and Preheating Activation: Add N-phenyl-α-naphthylamine, acidic bentonite (catalyst), and activated clay (adsorbent) sequentially to a dry four-necked flask. Then install a stirrer, thermometer, condenser, and dropping funnel. Turn on the stirrer and slowly heat to 70-100℃. Maintain this temperature for 30-40 minutes to ensure that the solid raw materials are melted and mixed evenly and to activate the catalyst. B2. Alkylation reaction: Add olefin to the dropping funnel. First, add 1 / 3 of the total amount of olefin into the flask at once. Continue stirring and heating to 110℃-180℃. After the system temperature stabilizes, slowly add the remaining 2 / 3 of the total amount of olefin into the flask. The adding time is 2-8 hours. After the addition is complete, keep the reaction at the temperature for 1-8 hours. Then turn on the reflux condenser and reflux the reaction for 2-10 hours. B3. Post-processing: After the reaction is complete, stop heating, add solvent to the reaction flask to fully dissolve the reaction product, filter while hot to separate and recover the catalyst for recycling, collect the filtrate, transfer it to a rotary evaporator, distill under reduced pressure to obtain crude product, add ethanol / water mixture (7:3), heat to 70℃ and stir to dissolve, then cool to 0℃, stand at constant temperature to precipitate crystals, filter under vacuum, wash 3 times with ice water, and dry under vacuum to obtain the self-made antioxidant.

[0016] As a further technical solution, the olefin is any of the isomers of C12-C14 α-olefins.

[0017] As a further technical solution, the solvent is toluene or petroleum ether.

[0018] As a further technical solution, the amount of acidic bentonite used is 10%-20% of the mass of N-phenyl-α-naphthylamine.

[0019] As a further technical solution, the amount of the activated clay is 5%-10% of the mass of N-phenyl-α-naphthylamine.

[0020] As a further technical solution, the molar ratio of the olefin to N-phenyl-α-naphthylamine is 2.1-2.3:1.

[0021] The structural formula of the self-made antioxidant prepared by the above method is as follows: This invention uses N-phenyl-α-naphthylamine as a substrate, which has an aromatic ring with a high electron cloud density, providing reaction sites for electrophilic substitution. An olefin is used as an alkylating agent. Under the catalysis of acidic bentonite, the double bond of the olefin accepts a proton to form a stable carbocation. The carbocation attacks the benzene ring of the substrate, and an alkylation reaction occurs, introducing a long-chain alkyl group into the benzene ring, thereby obtaining a self-made antioxidant.

[0022] N-Phenylacetylamine is a typical amine-type antioxidant with the ability to capture alkyl and peroxy radicals. By introducing long-chain alkyl groups onto the benzene ring, a "protective barrier" is formed around the amine group due to steric hindrance, which can delay the oxidative degradation of the amine group itself and significantly improve its high-temperature stability. In addition, the long-chain alkyl groups also enhance the oil solubility of the amine component, enabling it to be uniformly dispersed in turbine oil and continuously exert its antioxidant effect on the metal surface and the oil body, reducing the formation of varnish precursors such as carboxylic acids, aldehydes, and ketones.

[0023] The beneficial effects of this invention are: 1. This invention produces a synergistic effect by self-made antioxidants and compounding them with phenolic antioxidants, which greatly enhances the antioxidant capacity of oils and significantly reduces the generation of polar oxidation products that are precursors to paint films from the source. 2. Highly hydrotreated base oils are selected to provide ultra-high saturated hydrocarbon content, which not only improves the overall performance of the oil, but also results in a relatively low paint film tendency index. 3. Oil-soluble polyether is added as a key component. The polyether molecules utilize their polarity to effectively dissolve the polar oxidation products that have been generated or are forming in the system, preventing them from aggregating and depositing on the metal surface, thereby "cleaning" the system and reducing the paint film tendency index. 4. In the process of preparing homemade antioxidants, the catalyst can be recycled and reused, reducing costs; In summary, this technical solution achieves the core beneficial effect of significantly reducing turbine paint film tendency through the synergistic effect of "enhanced antioxidant capacity (reducing formation), improved solubility (removing precursors), and optimized base oil (stabilizing the foundation)", effectively extending equipment life and reducing unplanned downtime, and has important application value in the field of turbine oil technology. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 Preparation of homemade antioxidants: B1. Feeding and Preheating Activation: Add 21.9g of N-phenyl-α-naphthylamine, 2.2g of acidic bentonite (catalyst), and 1.1g of activated clay (adsorbent) to a dry four-necked flask. Then install a stirrer, thermometer, condenser, and dropping funnel, turn on the stirrer, slowly raise the temperature to 70℃, and keep it at this temperature for 30 minutes to make the solid raw materials melt and mix evenly and activate the catalyst. B2. Alkylation reaction: Add 35.28g of n-dodecene to the dropping funnel. First, add 1 / 3 of the total amount of n-dodecene to the flask at once, continue stirring and heating to 110°C. After the system temperature stabilizes, slowly add 2 / 3 of the total amount of olefin to the flask over 2 hours. After the addition is complete, keep the reaction at the temperature for 1 hour, then turn on the reflux condenser and reflux the reaction for 2 hours. B3. Post-processing: After the reaction is complete, stop heating and add toluene to the reaction flask to fully dissolve the reaction product. While hot, filter and separate to recover the catalyst for recycling. Collect the filtrate and transfer it to a rotary evaporator for vacuum distillation to obtain the crude product. Add an ethanol / water mixture (7:3), heat to 70°C and stir to dissolve, then cool to 0°C and stand at a constant temperature to precipitate crystals. Filter under vacuum, wash three times with ice water, and dry under vacuum to obtain the self-made antioxidant.

[0026] Example 2 Preparation of homemade antioxidants: B1. Feeding and Preheating Activation: Add 21.9g of N-phenyl-α-naphthylamine, 4.4g of acidic bentonite (catalyst), and 2.2g of activated clay (adsorbent) to a dry four-necked flask. Then install a stirrer, thermometer, condenser, and dropping funnel, turn on the stirrer, slowly raise the temperature to 100℃, and keep it at this temperature for 40 minutes to make the solid raw materials melt and mix evenly and activate the catalyst. B2. Alkylation reaction: Add 45.1g of n-tetradecene to the dropping funnel, and first add 1 / 3 of the total amount of n-dodecene to the flask. Continue stirring and heating to 180°C. After the system temperature stabilizes, slowly add 2 / 3 of the total amount of olefin to the flask over 8 hours. After the addition is complete, keep the reaction at the temperature for 8 hours, and then turn on the reflux condenser and reflux the reaction for 10 hours. B3. Post-processing: After the reaction is complete, stop heating and add petroleum ether to the reaction flask to fully dissolve the reaction product. While hot, filter and separate to recover the catalyst for recycling. Collect the filtrate and transfer it to a rotary evaporator for vacuum distillation to obtain the crude product. Add an ethanol / water mixture (7:3), heat to 70°C and stir to dissolve, then cool to 0°C and stand at a constant temperature to precipitate crystals. Filter under vacuum, wash three times with ice water, and dry under vacuum to obtain the self-made antioxidant.

[0027] Example 3 A method for preparing a low-varnish turbine oil includes the following steps: A1. In a reaction vessel, 0.3 parts of the self-made antioxidant prepared in Example 1, 0.5 parts of the phenolic antioxidant (antioxidant L135) and 88 parts of highly hydrogenated base oil are added, mechanical stirring is turned on, and the mixture is heated to 70°C to fully dissolve the raw materials and obtain a mixture. A2. Continue to add 5 parts of ethylene oxide / propylene oxide block copolymer, 0.05 parts of dodecenyl succinate half ester, 0.02 parts of methylbenzotriazole, 0.1 parts of pour point depressant (polymethyl methacrylate type pour point depressant 1-254) and 0.005 parts of antifoaming agent (T902E) to the reactor, and stir and mix for 0.5 h. Then cool to 40 °C to obtain low varnish turbine oil.

[0028] Example 4 A method for preparing a low-varnish turbine oil includes the following steps: A1. In a reaction vessel, 1.0 part of the self-made antioxidant prepared in Example 2, 1.0 part of the phenolic antioxidant (antioxidant L135) and 93 parts of highly hydrogenated base oil are added, mechanical stirring is started, and the mixture is heated to 80°C to fully dissolve the raw materials and obtain a mixture. A2. Continue to add 10 parts of ethylene oxide / propylene oxide block copolymer, 0.15 parts of dodecenyl succinic acid, 0.1 parts of methylbenzotriazole, 0.2 parts of pour point depressant (polymethyl methacrylate type pour point depressant 1-254) and 0.01 parts of antifoaming agent (T902E) to the reactor, and stir and mix for 1.5 hours. Then cool to 50°C to obtain low varnish turbine oil.

[0029] Comparative Example 1 The only difference between this comparative example and Example 4 is that no phenolic antioxidant was added in this comparative example to obtain turbine oil.

[0030] Comparative Example 2 The only difference between this comparative example and Comparative Example 1 is that in this comparative example, an equal amount of N-phenyl-α-naphthylamine was used to replace the self-made antioxidant to obtain turbine oil.

[0031] Comparative Example 3 The only difference between this comparative example and Example 4 is that in this comparative example, an equal amount of N-phenyl-α-naphthylamine was used to replace the self-made antioxidant to obtain turbine oil.

[0032] The performance of Example 4 and Comparative Examples 1, 2 and 3 was measured, and the results are shown in Table 1: Table 1 As shown in Table 1, the paint film tendency index of Example 4 of this application, which contains self-made and phenolic antioxidants, is significantly lower than that of the formulation containing traditional PNAN (N-phenyl-α-naphthylamine). Therefore, its paint film control ability is far superior to that of the formulation using traditional PNAN (N-phenyl-α-naphthylamine). Furthermore, the combination of phenolic antioxidants and self-made antioxidants in the examples also has a much longer 150°C rotating oxygen bomb induction period than the comparative example, which has important application value in the field of turbine oil technology.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing low-varnish turbine oil, characterized in that, Includes the following steps: A1. In the reaction vessel, add the self-made antioxidant, phenolic antioxidant and base oil, turn on the mechanical stir and heat to 70-80℃ to fully dissolve the raw materials and obtain a mixture; A2. Continue to add oil-soluble polyether, rust inhibitor, metal deactivator, pour point depressant and antifoaming agent to the reactor, and stir and mix for 0.5-1.5 hours. Then cool to 40-50°C to obtain low-film turbine oil.

2. The method for preparing low-varnish turbine oil according to claim 1, characterized in that, The raw materials are as follows by weight: 88-93 parts base oil, 5-10 parts oil-soluble polyether, 0.3-1.0 parts self-made antioxidant, 0.5-1.0 parts phenolic antioxidant, 0.05-0.15 parts rust inhibitor, 0.02-0.1 parts metal deactivator, 0.1-0.2 parts pour point depressant, and 0.005-0.01 parts antifoaming agent.

3. The method for preparing low-varnish turbine oil according to claim 1, characterized in that, The homemade antioxidant is prepared through the following steps: B1. Add N-phenyl-α-naphthylamine, acidic bentonite and activated clay to the flask in sequence, start stirring, slowly heat to 70-100℃, and keep warm for 30-40 minutes. B2. Add 1 / 3 of the total amount of olefins dropwise into the flask, stir and heat to 110℃-180℃. After the system temperature stabilizes, add the remaining 2 / 3 of the total amount of olefins dropwise into the flask. The dropwise addition time is 2-8 hours. After the addition is complete, keep the temperature at 1-8 hours and turn on the reflux device to reflux for 2-10 hours. B3. After the reaction is complete, stop heating, add solvent to the reaction flask, filter while hot to separate and recover the catalyst, collect the filtrate, transfer it to a rotary evaporator, distill under reduced pressure to obtain crude product, add ethanol / water mixture, heat to 70℃ and stir to dissolve, then cool to 0℃, stand at constant temperature to precipitate crystals, filter under vacuum, wash, and dry under vacuum to obtain the self-made antioxidant.

4. The method for preparing low-varnish turbine oil according to claim 3, characterized in that, The olefin is all isomers of C12-C14α-olefins.

5. The method for preparing low-varnish turbine oil according to claim 3, characterized in that, The amount of acidic bentonite used is 10%-20% of the mass of N-phenyl-α-naphthylamine.

6. The method for preparing low-varnish turbine oil according to claim 3, characterized in that, The amount of activated clay used is 5%-10% of the mass of N-phenyl-α-naphthylamine.

7. The method for preparing low-varnish turbine oil according to claim 3, characterized in that, The molar ratio of the olefin to N-phenyl-α-naphthylamine is 2.1-2.3:

1.

8. The method for preparing low-varnish turbine oil according to claim 1, characterized in that, The base oil is a highly hydrotreated base oil.

9. The method for preparing low-varnish turbine oil according to claim 1, characterized in that, The oil-soluble polyether is an ethylene oxide / propylene oxide block copolymer.

10. The method for preparing low-varnish turbine oil according to claim 1, characterized in that, The phenolic antioxidant is a hindered phenolic antioxidant.

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